biology

biology

Browse the evolutionary tree map

1. OneZoom: Tree of Life Explorer

OneZoom is a very sophisticated and interactive tree of life tool that allows users to browse the evolutionary relationships of all known species on Earth. This platform draws all species into a spiral "pod", with each leaf representing a species and showing the evolutionary connections between species. OneZoom Provides an intuitive and explorable way to understand the diversity of life and is useful for education and scientific research. you canOneZoomTry this tool on the website.

2. Tree of Life Web Project

Tree of Life Web Project It is an open and free platform focused on displaying the evolutionary relationships of all known organisms. This website provides a large amount of data from various fields of biology and visually displays the relationships between species. It is suitable for academic research and educational use. It is an ideal tool for studying evolutionary biology.

3. PhyloPic

PhyloPic provides an online image library containing pictures of various species that can be used to enrich the visual presentation of evolutionary trees. Users can combine these images with evolutionary trees to further help understand the evolutionary relationships between species. This platform is ideal for education in biology and evolution.

These tools have powerful visualization functions and can help scholars and students gain an in-depth understanding of the evolution of life. If you want to explore further, you can visit directlyOneZoomto interact.

Evolutionary geological time

geological time representative

Hypothesis about the origin of life in submarine chimneys

core concepts

• The hypothesis of the origin of life in submarine chimneys suggests that life may have originated near hydrothermal vents (submarine chimneys) in the deep sea, rather than on the surface or in shallow seas.
• These environments provided energy, chemicals, and protective conditions that were conducive to the formation and evolution of primitive life.

Environmental characteristics of submarine chimneys

• Located in the rupture or subduction zone of the seafloor plate, seawater penetrates into the earth's crust and is heated, and then erupts carrying minerals.
• The temperature can range from tens of degrees to over 300°C, forming obvious temperature and chemical gradients.
• Rich in sulfide, hydrogen, methane, iron, nickel and other reducing substances.

Energy source and metabolic starting point

• Unlike today's ecosystems that rely on solar energy, the submarine chimney ecosystem is based onchemical synthesisas a basis.
• Primitive life may have used hydrogen, hydrogen sulfide, etc. to react with carbon dioxide to obtain energy and synthesize organic molecules.
• This metabolism is similar to that of some modern archaea and bacteria.

Mineral catalysis and primitive cell formation

• The chimney wall is composed of porous iron sulfide, nickel sulfide and other minerals, which can form a natural micro reaction chamber.
• These holes concentrate organic molecules, promoting chemical reactions and avoiding dilution by seawater.
• Mineral surfaces may be catalytic, helping to form amino acids, lipids and simple metabolic pathways.

Adaptability to early Earth environments

• The surface of the early Earth may have been subject to strong ultraviolet rays and meteorite impacts, making the environment unstable.
• The deep sea environment is relatively stable and can provide shielding to protect primitive life.
• It does not rely on oxygen and is consistent with the oxygen-deficient atmospheric conditions of the early Earth.

Supporting evidence and relevant observations

• Modern deep-sea hydrothermal vents contain highly prosperous ecosystems that are completely independent of photosynthesis.
• Many archaea and bacteria located at the roots of the tree of life have metabolic patterns that are highly compatible with hydrothermal environments.
• Experiments have shown that a variety of life-related organic molecules can be synthesized under chimney-like conditions.

Main limitations and controversies

• High temperatures may destroy some complex organic molecules, requiring low temperature zones and gradient environments.
• How the transition from mineral pores to a true cell membrane structure is still not fully explained.
• There is still integration and competition with other origin of life hypotheses (e.g. primordial soup, RNA world).

Ediacaran

Times position

The Ediacaran Period is the last period of the Neoproterozoic in the Proterozoic Eon. It is located after the Ice Age (about 635 million years ago) and before the Cambrian (541 million years ago). This is the first geological period in Earth's history to be named after a biological feature.

Naming and discovery

The name Ediacaran comes from the Ediacara Hills in southern Australia, where well-preserved soft-bodied fossils were first discovered in 1946. In 2004, the International Commission on Stratigraphy officially listed it as a standard geological period.

Biometrics

• Large, multicellular, complex organisms emerged, collectively known as the "Ediacaran Biota."
• Most of the organisms are soft-bodied and without bones, and their shapes include disc-shaped, feather-shaped, tube-shaped, etc.
• Typical fossils include Dickinsonia, Charniodiscus, and Tribrachidium.
• Some may be early animals, while others belong to unique taxa that have become extinct.

environment and evolution

Atmospheric oxygen levels increased significantly during this period, which may have promoted the development of complex life. As the global climate stabilizes and ice ages end, the ocean provides a more stable habitat and promotes the evolution of multicellular organisms.

Strata and Fossils

Ediacaran fossils are commonly found in sandstone and siltstone in shallow marine sediments and are distributed around the world, including Australia, Russia, Canada, Namibia and China.

importance

The Ediacaran Period was a critical period in the evolution of animal life, witnessing a major leap from microbial dominance to large multicellular organisms, laying the foundation for the Cambrian explosion of life.

Carboniferous

1. Era and geological location

• The Carboniferous Period is a period in the Paleozoic Era, approximately between359 million to 299 million years ago。
• This period was after the Devonian and before the Permian.
• The name "Carboniferous" means "carbon-containing" because coal seams were formed in large quantities during this period.

2. Climate and environment

• The initial climate is warm and humid, suitable for plant growth.
• In the later period, the climate became dry and cold, and the supercontinentPangearelated to its formation.
• The oxygen concentration was extremely high, about 1.5 times that of today, making insects and amphibians extremely large.

3. Reasons for the increase in oxygen concentration

• During the Carboniferous period, widespreadswamp forest, plant photosynthesis proceeds vigorously, absorbing large amounts of carbon dioxide and releasing oxygen.
• After the plants died, they were buried in a humid and oxygen-free peat environment and were not completely decomposed, forming a large amount of organic carbon deposits.
• These carbonaceous deposits are eventually converted intocoal seam, which is equivalent to "storing" carbon in the earth's crust, causing the proportion of oxygen in the atmosphere to increase.
• Since decomposing bacteria (especially lignin-decomposing bacteria) have not yet fully evolved and matured, the woody fibers of plants are not easily decomposed, further strengthening the carbon sequestration effect.
• The result is that atmospheric oxygen concentrations can be as high asAbout 30% to 35%, much higher than the modern rate of about 21%.

4. Plant and forest development

• The swamp forest is dominated by ferns, horsetails, and lycophytes, forming a tall and dense forest belt.
• The emergence of the first gymnosperms with seeds (such as seed ferns) was an important milestone in the evolution of land plants.

5. Evolution of fauna

• Amphibians flourished and became the vertebrates that dominated land.
• The earliestamniotes, the ancestors of later reptiles, birds and mammals.
• The growth of insects, such as the giant dragonfly (Meganeura) with a wingspan of up to 70 centimeters, is closely related to high oxygen concentrations.

6. Geological events and ecological changes

• The northern continent Laurasia and the southern Gondwana gradually approached each other, forming the prototype of Pangea.
• Late appearanceice age, causing sea level drops and ecological changes.
• Climate changes at the end of this period set the stage for the evolution of Permian flora and fauna.

branch of biological evolution

biochemistry

definition

Biochemistry is the science that studies chemical substances and reactions in living organisms. It combines chemistry and biology to explore the molecular basis of life.

Research object

• protein
• Nucleic acids (DNA, RNA)
• Lipids
• carbohydrate
• Enzymes and Metabolites

core themes

1. Biological macromolecules

• protein:Composed of amino acids, it has structural, catalytic, transport, signaling and other functions.
• Nucleic acids:Stores and transmits genetic information and controls protein synthesis.
• Lipids:Forms the cell membrane and is an important source of energy storage.
• carbohydrate:Supplies energy and also serves as cell identification and structural component.

2. Enzymes and Catalysis

• Enzymes are specific biological catalysts that speed up chemical reactions.
• Studying the structure, mechanism of action, inhibitors and regulatory mechanisms of enzymes is the core content.

3. Metabolism

• Metabolism is the sum of chemical reactions carried out in living organisms, which is divided into:
• Assimilation:Synthetic reactions (such as protein synthesis, photosynthesis)
• Alienation:Decomposition reactions (e.g. glucose breaks down to release energy)

4. Molecular messaging

• Cells communicate through signaling molecules and receptors, such as hormones and second messenger systems (such as cAMP)
• Affects gene expression, enzyme activity and cell behavior

Application areas

• Pharmaceutical development (e.g. drug targets, enzyme inhibitors)
• Genetic Engineering and Biotechnology
• Disease diagnosis and treatment (such as cancer, diabetes, genetic diseases)
• Nutrition and Food Science

Conclusion

Biochemistry reveals the molecular mechanisms of life and is an important foundation for modern life science and medical research, helping us understand health, disease and the nature of life.

molecular biology

definition

core concepts

• DNA (deoxyribonucleic acid): Stores genetic information and is the carrier of genetic material.
• RNA (ribonucleic acid): Responsible for the transcription and translation of genetic information.
• protein: Synthesis is guided by RNA and is responsible for most functions and structures in cells.
• central dogma: Genetic information is copied from DNA, transcribed into RNA, and finally translated into protein.

Main process

• DNA replication: Before cells divide, DNA will be accurately copied to ensure that genetic information is passed on.
• Transcribe: The DNA sequence is transcribed into mRNA, which serves as a template for protein synthesis.
• translate: The mRNA is interpreted in the ribosome, and the corresponding amino acid chain is synthesized to form a protein.

Application areas

• Genetic Engineering and Genetically Modified Organisms
• Biotech drugs (e.g. insulin, monoclonal antibodies)
• Disease diagnosis and gene therapy
• DNA testing and paternity testing

Commonly used techniques

• PCR (polymerase chain reaction): used to rapidly amplify DNA fragments.
• Electrophoresis: A tool for separating DNA, RNA, or proteins.
• Gene sequencing: Used to decipher the sequence of bases in DNA.
• CRISPR/Cas9: Gene editing technology that can precisely modify genes.

Relevance to other disciplines

Nucleotide

definition

Nucleotides are the basic units that make up DNA and RNA and are also involved in various biochemical reactions within cells. Each nucleotide is made up of three parts:

• A nitrogenous base (Nitrogenous base)
• A five-carbon sugar (Pentose sugar)
• One to three phosphate groups (Phosphate group)

Base type

• DNA：Adenine (A), guanine (G), cytosine (C), thymine (T)
• RNA：Adenine (A), guanine (G), cytosine (C), uracil (U)

five carbon sugar

• DNA：Deoxyribose
• RNA：Ribose

The difference between nucleosides and nucleotides

• Nucleoside:Contains only bases and five-carbon sugars
• Nucleotide:Nucleoside plus one or more phosphate groups

The role of nucleotides in DNA and RNA

Nucleotides are linked together in a polymeric manner to form long chains of DNA or RNA. Phosphoric acid and sugar form the main chain, and the bases are arranged inward to form genetic information.

• DNA has a double helix structure, consisting of two nucleotide chains stably combined through base pairing (A-T, G-C)
• RNA is a single-stranded structure that participates in protein synthesis and other functions.

Other important nucleotides

• ATP (adenosine triphosphate):Cellular energy currency, supplying the energy needed for metabolism
• cAMP (cyclic adenosine monophosphate):Second messenger for intracellular signaling
• NAD⁺/FAD：Coenzymes involved in redox reactions

Function summary

• Constituting DNA and RNA, carrying and transmitting genetic information
• Participate in energy transfer and cell metabolism
• Acts as a signaling molecule to regulate cell function

Nitrogenous base

definition

Nitrogen-containing bases refer to nitrogen-containing organic cyclic compounds in nucleic acid molecules. They are alkaline and can react with acids to form salts. They are important components of DNA and RNA and are responsible for the storage and transmission of genetic information.

Main types

Nitrogenous bases can be divided into two broad categories:

• Purines:Contains a double ring structure, represented by adenine (A) and guanine (G)
• Pyrimidines:Contains a single ring structure, represented by cytosine (C), thymine (Thymine, T, only found in DNA) and uracil (U, only found in RNA)

Function

Nitrogenous bases form base pairing through hydrogen bonds, which is the key to the double-stranded structure of nucleic acids:

• In DNA: A pairs with T, G pairs with C
• In RNA: A pairs with U, G pairs with C

biological significance

The base sequence determines the sequence of protein synthesis and constitutes the genetic code of the gene. During replication, transcription and translation, base pairing ensures the correct transmission of information.

Other applications

Nitrogen-containing base derivatives are also used in drug design (such as antiviral drugs and chemotherapy drugs), and as probes, labels and reaction substrates in biochemical experiments.

DNA

What is DNA?

DNA, the full name is Deoxyribonucleic Acid, is a molecule that carries genetic information. It is the genetic material of all known organisms (including many viruses) and is responsible for directing the development, growth, reproduction and physiological functions of organisms.

structure of DNA

The molecular structure of DNA is a double helix, made up of two intertwined long chains of nucleotides. Each nucleotide is made up of three parts:

• Phosphoric acid
• Five-carbon sugar (deoxyribose)
• Nitrogenous bases (adenine A, thymine T, guanine G, cytosine C)

The bases combine according to specific pairing rules: A matches T, G matches C.

functions of DNA

The primary function of DNA is to store and transmit genetic information. It works in the following ways:

• clone:DNA replicates itself, passing genetic information to the next generation of cells.
• Transcription and translation:DNA information is transcribed into RNA, which is then translated into proteins to complete the life activities of organisms.

DNA applications in science and medicine

DNA has a wide range of applications in modern science and medicine, such as:

• Diagnosis and treatment of genetic diseases
• Genetic engineering and gene editing technologies (such as CRISPR)
• Identity confirmation in forensic science
• biological evolution research

Conclusion

DNA is the core code of life. Understanding its structure and function not only allows us to uncover the mysteries of the biological world, but also brings unlimited possibilities to the development of human technology and medical care.

RNA

What is RNA?

RNA (Ribonucleic Acid) is a biological molecule composed of nucleotides, and participates in the storage and expression of genetic information together with DNA. RNA is usually a single-stranded molecule, unlike DNA's double-stranded structure.

RNA structure

The basic unit of RNA is a nucleotide, each of which consists of ribose (sugar molecule), a phosphate group, and one of four nitrogen groups (adenine A, guanine G, cytosine C, and uracil U). Uracil (U) in RNA replaces thymine (T) in DNA.

Types of RNA

• Messenger RNA (mRNA):Responsible for carrying genetic information on DNA and used to guide protein synthesis.
• Transfer RNA (tRNA):Transports amino acids to ribosomes during protein synthesis.
• Ribosomal RNA (rRNA):It is the main component of ribosomes and participates in protein synthesis.
• Other non-coding RNAs:Such as miRNA and siRNA, involved in gene expression regulation and RNA interference.

RNA function

• Transmit genetic information and guide protein synthesis.
• Serves as a catalyst within cells, such as ribozymes.
• Involved in the regulation of gene expression.
• As genetic material in viruses, such as the genome of the new coronavirus (SARS-CoV-2).

Difference Between RNA and DNA

The main differences between RNA and DNA are structure and function: RNA is a single strand, ribose replaces DNA's deoxyribose, and uracil (U) replaces DNA's thymine (T). In addition, RNA usually performs dynamic functions within cells, while DNA is mainly responsible for stable storage of genetic information.

RNA Research Applications

RNA has important applications in biomedical research, such as RNA vaccines (such as mRNA vaccines), RNA interference technology (RNAi) and gene therapy, etc., bringing new possibilities for disease diagnosis and treatment.

Gene

definition

Gene refers to the functional genetic unit that exists in the DNA of an organism (or the RNA of some viruses) and is the basic unit of genetic information. Each gene contains instructions for making a protein or RNA, controlling an organism's traits, functions, and development.

Structure and composition

• DNA sequence: Genes are composed of DNA sequences composed of nucleotides, and the order determines the content of genetic information.
• Exon: The part that can be translated into protein.
• Intron: Not involved in protein coding, but may have regulatory functions.
• Promoter: Controls the turning on and off of gene expression.

Function

• Directs cells to make proteins.
• Regulates cellular activities and metabolic pathways.
• Determines genetic characteristics such as eye color, blood type, enzyme activity, etc.
• Participate in physiological processes such as growth, development, immunity and behavior.

Inheritance

Genes are passed from parents to offspring through chromosomes during reproduction. The main genetic modes include:

• Dominant and recessive inheritance: Dominant genes will be expressed in a heterozygous state, while recessive genes require two copies to be expressed.
• sex-linked inheritance: The gene is located on a sex chromosome, such as the X or Y chromosome.
• mitochondrial inheritance: Mitochondrial DNA is passed down through the maternal line.

genetic mutation

Genes may mutate due to natural or external factors, changing their DNA sequence, which may lead to:

• Genetic diseases (such as cystic fibrosis, thalassemia).
• Cancer and other cells proliferate out of control.
• Generate new biodiversity.

application

• medicine: Gene therapy, cancer detection, personalized medicine.
• agriculture: Genetically modified crops to improve disease resistance and yield.
• Forensic: DNA identification.
• Evolutionary research: Compare genes of different species to understand evolutionary history.

Genes and genomes

A gene is a piece of DNA, and the total number of genes in an organism is called the "genome". The human genome contains approximately 20,000 to 25,000 genes, consisting of approximately 3 billion DNA base pairs.

protein

definition

Protein is a macromolecular compound composed of amino acids linked through peptide bonds. It is one of the most important biomolecules in life. It is responsible for forming cell tissues and participating in various physiological functions.

structural level

• primary structure: Arrangement order of amino acids.
• secondary structure: Such as α-helix and β-sheet, which are stably formed by hydrogen bonds.
• tertiary structure: The three-dimensional structure of the overall protein.
• Quaternary structure: A composite structure composed of multiple protein subunits (such as heme).

Main functions

• structural support: Such as collagen that makes up skin, tendons and bones.
• catalytic reaction: Enzymes are proteins that can accelerate biochemical reactions.
• transportation: For example, heme carries oxygen and transport proteins across cell membranes.
• messaging: Hormones (such as insulin) and receptors regulate physiological activities.
• immune defense: Antibodies are proteins that can identify and neutralize pathogens.
• Kinetic energy generation: Muscle proteins (such as actin, myosin) assist cells and muscles in contraction.

source of protein

• animality: Meat, fish, eggs, milk, containing complete amino acids.
• plant based: Beans (soybeans, black beans), cereals (brown rice, quinoa), nuts, etc.

synthesis and decomposition

• synthesis: In the nucleus, DNA is transcribed into mRNA, which is then translated into protein by ribosomes.
• break down: Excess or aged proteins in the body will be broken down by enzymes into amino acids for recycling.

nutritional value

Protein is one of the three major nutrients (the other two are carbohydrates and fats) and is essential for maintaining muscle mass, repairing tissues, and producing enzymes and immune proteins. The recommended daily intake for adults is about 0.8 grams per kilogram of body weight, and athletes have higher needs.

health connection

• insufficient: May cause muscle loss, decreased immunity, and developmental delay.
• excess: May increase the burden on the kidneys, especially patients with kidney disease need special attention.

application

• Medicine: Manufacturing of insulin, vaccines and antibody drugs.
• Food Technology: Plant-based proteins developed as meat alternatives.
• Scientific research: protein crystallography, protein engineering and synthetic biology and other fields.

Mitochondria

structure

• adventitia:Covers the entire mitochondria and has selective permeability.
• Intima:Folds inward to form wrinkles (ridges) that increase surface area and contain electron transport chains.
• Intermembrane space:The space between the outer membrane and the inner membrane participates in the formation of the proton gradient.
• Substrate:The area surrounded by the inner membrane contains DNA, ribosomes and metabolic enzymes.

Function

• Energy production:ATP is produced through oxidative phosphorylation and is the energy factory of cells.
• Metabolic regulation:Participate in metabolic pathways such as fatty acid oxidation and citric acid cycle.
• Calcium ion storage:Assists in the regulation of intracellular calcium ion concentration.
• Apoptosis:Release of cytochrome c initiates programmed cell death.
• Own genetic material:It has its own DNA and can synthesize some proteins.

adenosine triphosphate ATP

structure

• Full name:Adenosine Triphosphate.
• composition:Consists of one adenosine (adenine + ribose) and three phosphate groups.
• High energy bonds:The bonds between the three phosphate groups are high-energy phosphate bonds, especially the two terminal bonds, which can release a large amount of energy during hydrolysis.

Function

• Energy Currency:ATP is the direct source of energy in cells and is used to drive various biochemical reactions.
• Activating reactants:Reactants become more reactive through phosphorylation.
• Cell activities:Provide energy for muscle contraction, nerve conduction, active transport and other cell activities.
• Reversible reaction:After ATP is hydrolyzed to ADP + Pi, it can be regenerated and synthesized to maintain cellular energy cycle.

photosynthesis

Basic concepts

Photosynthesis is the process by which plants, algae and some bacteria convert light energy into chemical energy, mainly producing glucose and oxygen. This process is the main source of energy and oxygen for Earth's ecosystem.

Chemical reaction formula

6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂

Action steps

1. Light reaction:Occurring in the thylakoids of chloroplasts, they absorb light energy and produce ATP and NADPH, while releasing oxygen.
2. Dark reaction (Calvin cycle):Occurs in the chloroplast stroma, using ATP and NADPH generated by light reactions to fix carbon dioxide and synthesize glucose.

Impact factor

• Light intensity: The stronger the light, the faster the rate of photosynthesis is usually, but too much light may inhibit it.
• Carbon dioxide concentration: CO₂Increasing concentration can speed up the reaction, but there is a saturation value.
• Temperature: Appropriate temperature helps enzyme activity, but too high or too low will inhibit it.
• Moisture: Lack of water will cause stomata to close and affect CO₂absorb.

Ecology and Application

• Maintains the balance of oxygen and carbon dioxide in the atmosphere.
• Provides a major source of biological energy.
• Used in agriculture, improving crop photosynthesis efficiency can increase yields.
• Artificial photosynthesis research for energy and environmental technology.

Turing Patterns in Biological Forms

Turing model and morphogenesis

• Turing proposed in his paper "The Chemical Basis of Morphogenesis" that the morphological structures of animals and plants (such as spots, nodes, and protrusions) can be produced by the diffusion and reaction of chemical substances during embryonic development.
• This model breaks the concept that "morphology is completely controlled by genes" and emphasizes that genes only set the initial conditions, and the morphological structure is naturally self-organized by chemical and physical dynamics.

Exciter and inhibitor mechanisms

• Activator:Promotes the production of itself and inhibitors, usually spreading slowly.
• Inhibitor:Inhibits the activity or generation of initiators and causes faster diffusion.
• This asymmetric diffusion rate creates an uneven distribution in space, forming a stable and regular pattern.

Examples in living organisms

• Animal skin patterns:For example, leopard's spots, zebra's stripes, tropical fish's mesh pattern, etc. can be regarded as patterns produced by different excitation/inhibition substances at developmental stages.
• Development of limbs and toes:In the early stages of embryonic development, the Turing mechanism determines the position and number of knuckles.
• Hair follicles and feathers:Hair follicle formation in mice and birds shows a spotted distribution, consistent with Turing model predictions.
• Plant phyllotaxis and petal arrangement:The reaction-diffusion model can simulate plant bud point distribution and spiral inflorescence production.

The connection between genes and Turing mechanism

• Genes regulate the synthesis and distribution of stimulators and inhibitors, but the actual formation of patterns relies on the physical process of reaction-diffusion.
• For example, in the formation of skin markings in zebrafish, genes related to the interaction of pigment cells have been found, and their expression affects the output of the Turing mechanism.

Simulation and verification

• Modern computers can simulate Turing patterns under different parameters and successfully reproduce common patterns in nature.
• Through genetic engineering and experimental operations, scientists have induced or changed patterns in animal models, further verifying the feasibility of the Turing mechanism.

Virus

structure

• Genome:It can be DNA or RNA, single-stranded or double-stranded, and carries the genetic information required for virus replication and infection.
• Protein coat (capsid):Composed of proteins that protect the viral genome and assist in attachment to host cells.
• Envelope (some viruses):Derived from the host cell membrane, it contains virus-specific glycoproteins that facilitate entry into host cells.

characteristic

• Non-cellular organisms:It has no cellular structure and cannot metabolize and reproduce on its own.
• Needs parasitic reproduction:It must invade the host cell and use its machinery to replicate and assemble.
• Highly specific:Most viruses infect only specific types of cells or organisms.
• Rapid mutations:In particular, RNA viruses have a high mutation rate, which is conducive to evading the immune system.

reproductive cycle

• Adsorption:Viruses attach to receptors on the surface of host cells.
• Penetration and shelling:The virus enters the cell and releases its genome.
• Copy and translate:The host system is used to replicate viral nucleic acids and synthesize proteins.
• Assembly:The newly produced viral components are assembled into complete viruses within the cell.
• release:The virus leaves the host cell and infects more cells, possibly with cell rupture.

non-pathogenic viruses

semantic issues

academic use

• Phage viruses: Viruses that infect bacteria and can be used to treat drug-resistant bacterial infections.
• Endogenous viral elements: Viral sequences present in the host genome, partially involved in gene regulation.
• Plant growth-promoting viruses: Certain plant viruses can improve plant tolerance to stress.

Neutral or positive expression

• non-pathogenic viruses
• Symbiotic virus
• Mutualistic virus
• Viral symbiont
• Temperate virus: refers to a virus that does not damage the host

Need a new term?

• "Virus" has become a fixed term in taxonomy and virology.
• The biological definition of a virus does not depend on whether it causes disease.
• Adding modifiers is more practical than creating new words, and is easier for the public to understand and accept.

in conclusion

cell

Cell overview

• Cells are the most basic structural and functional units of organisms. All organisms are composed of one or more cells.
• It is divided into two major categories according to structure:prokaryotic cellsandeukaryotic cells。

prokaryotic cells

• There is no nucleus, and its DNA is located in the nuclear region of the cytoplasm.
• Simple structure, no membranous organelles.
• Represents: Bacteria and Archaea.

eukaryotic cells

• It has a nucleus and a variety of membranous organelles and has a complex structure.
• Including plant cells, animal cells, fungi and protists.

main structure of cells

• cell membrane:Composed of a lipid bilayer that controls the entry and exit of substances.
• Cytoplasm:The intracellular liquid environment contains various organelles.
• Nucleus:Contains DNA and controls cellular activities (only found in eukaryotic cells).
• Ribosomes:Site of protein synthesis, either free or attached to the rough endoplasmic reticulum.
• Endoplasmic reticulum:Synthesis and transport of proteins (rough) and lipids (smooth).
• High base body:Modify, package and transport proteins.
• Mitochondria:Produces ATP, which is the energy factory of cells.
• Solution:Break down waste products and intracellular materials (in animal cells).
• Liquid cells:Stores water and nutrients (usually larger in plant cells).
• Cell wall:Made of cellulose, which provides support and protection (specific to plant cells).
• Chloroplasts:Carry out photosynthesis (specific to plant cells).

cell function

• Metabolism:Carry out synthesis and decomposition reactions to maintain life activities.
• Energy conversion:Convert nutrients into ATP for use by cells.
• Reproduction and division:Propagation and inheritance through mitosis or meiosis.
• Reaction and adjustment:Sensing and responding to external stimuli.
• Differentiation and specialization:In multicellular organisms, cells develop into types with different functions.

stem cells

Basic concepts

Stem cells are a type of cells that have the ability to self-renew and differentiate into many different cell types. They play key roles in the growth, tissue repair and regeneration of organisms and are an important basis for regenerative medicine and biomedical research.

Main features

• Self-update:It can maintain its own number for a long time through cell division.
• Differentiation potential:Can transform into functional cells under certain conditions.

Classification according to differentiation ability

• Totipotent stem cells:All cell types that can differentiate into a complete individual, such as a fertilized egg.
• Pluripotent stem cells:Can differentiate into various cells derived from the three germ layers, such as embryonic stem cells.
• Pluripotent stem cells:Cells that can differentiate into specific tissue systems, such as hematopoietic stem cells.
• Unipotent stem cells:Can only differentiate into a single cell type, such as stem cells in the basal layer of the skin.

Classified by source

• Embryonic stem cells:Taken from early embryos, they have the strongest differentiation ability.
• Adult stem cells:Found in mature organizations and responsible for tissue renewal and repair.
• Induced pluripotent stem cells:Genetically reprogrammed from adult cells, it has characteristics similar to embryonic stem cells.

Clinical and research applications

• Treatment of blood disorders, such as bone marrow transplant.
• Regenerative medicine is used to repair nerves, myocardium, cartilage and other tissues.
• Disease modeling and drug testing.
• Gene therapy and precision medicine research.

Ethics and Risk

Embryonic stem cells involve bioethical controversies, and stem cell therapy may still involve risks such as tumor formation, immune rejection, and uncontrolled differentiation. Therefore, clinical application requires strict review and testing.

Development status

With the advancement of induced pluripotent stem cells and gene editing technology, stem cell research is developing rapidly and has high potential in disease treatment and tissue regeneration in the future.

bacteria

Basic characteristics

Morphological classification

• Coccus:Such as Staphylococcus aureus.
• Bacillus:Such as E. coli.
• Spirillum:Such as Treponema pallidum.
• Vibrio:Such as Vibrio cholerae.

Physiological properties

• Aerobic bacteria:Need oxygen to survive.
• Anaerobic bacteria:Survive in an oxygen-free environment.
• Facultative anaerobic bacteria:Can grow in aerobic or anaerobic environments.

Reproduction method

Dyeing and classification

• Gram-positive bacteria:The cell wall is thick and stained purple.
• Gram-negative bacteria:The cell wall is thin and stained pink.

relationship with humans

• Beneficial bacteria:For example, intestinal bacteria assist digestion, nitrogen-fixing bacteria help plants absorb nitrogen, and lactic acid bacteria make yogurt.
• Harmful bacteria:Such as pathogenic bacteria that cause pneumonia, cholera, tuberculosis, syphilis and other diseases.

Antibiotics and resistance

Application areas

• E. coli is used in genetic engineering to produce insulin.
• Lactic acid bacteria are used to make cheese, miso and other foods.
• Use decomposing bacteria for sewage treatment and soil purification.

staphylococcus

Basic characteristics

Staphylococcus is a type of Gram-positive cocci that are often arranged in "grape bunches" and are facultative anaerobes. Such bacteria widely exist in nature and in human skin and mucous membranes. Most are commensal bacteria, but some can become important pathogens.

Classification

Staphylococci are divided into two categories based on whether they produce coagulase:

• Coagulase positive:The most representative one is Staphylococcus aureus (S. aureus), which is an important pathogenic bacteria.
• Coagulase negative:For example, Staphylococcus epidermidis (S. epidermidis) and Staphylococcus saprophyticus (S. saprophyticus) are mostly opportunistic infectious bacteria.

important categories

• Staphylococcus aureus:Can cause skin purulent infections, pneumonia, sepsis, endocarditis, and food poisoning.
• Staphylococcus epidermidis:Often associated with infections related to artificial medical devices.
• Staphylococcus saprophyticus:Often leads to urinary tract infections, especially in young women.

Pathogenic mechanism

Staphylococci can secrete a variety of toxins and enzymes, including:

• Hemolysin, leukopenkin: destroy cells.
• Enterotoxins: Cause food poisoning.
• Exfoliative toxin: Causes burn-like skin syndrome.
• Protein A: interferes with host immunity.

clinical symptoms

• Skin and soft tissue infections: abscesses, boils, cellulitis.
• Respiratory tract infection: pneumonia.
• Cardiovascular system: endocarditis, sepsis.
• Poisoning reactions: food poisoning, toxic shock syndrome.

drug resistance problem

Multidrug-resistant strains of Staphylococcus aureus have emerged, the most famous of which areMethicillin-resistant Staphylococcus aureus (MRSA), is a clinically important drug-resistant pathogen, and treatment relies on special antibiotics such as vancomycin.

Prevention and treatment

• Maintain personal and hospital environmental hygiene to reduce cross-infection.
• Avoid indiscriminate use of antibiotics to reduce the emergence of drug-resistant strains.
• Clinical infections require drug susceptibility testing and effective antibiotic treatment.

Streptococcus

Basic characteristics

Streptococcus is a type of Gram-positive cocci that usually appear in chains or pairs. They are facultative anaerobic bacteria, and some species can live symbiotically in humans or animals, but many are also important pathogenic bacteria.

Classification

Streptococci can be divided into three major categories based on their hemolytic properties:

• Alpha hemolytic:Partial hemolysis, green ring on blood agar, such as Streptococcus pneumoniae.
• Beta hemolytic:Complete hemolysis with a transparent ring around it, such as Streptococcus pyogenes.
• γHemolytic:No hemolytic reaction.

important categories

• Streptococcus pyogenes (S. pyogenes):Can cause pharyngitis, scarlet fever, rheumatic fever, abscesses, etc.
• Streptococcus pneumoniae (S. pneumoniae):Cause pneumonia, otitis media, meningitis, etc.
• Group B Streptococcus (S. agalactiae):Commonly seen in neonatal infections and urinary tract infections in pregnant women.
• Oral Streptococci (S. mutans, etc.):Related to dental caries.

Pathogenic mechanism

Streptococci can cause infection and tissue damage through the production of exotoxins, hemolysins and immune evasion mechanisms. Some can induce an immune response that can lead to complications such as rheumatic fever or glomerulonephritis.

clinical significance

Streptococcal infections are very common in humans, ranging from mild strep throat to severe sepsis. Its diagnosis relies on bacterial culture, antigen detection or molecular biology methods.

Treatment and Prevention

Antibiotics such as penicillin or cephalosporins are commonly used for treatment, but some strains have become resistant to antibiotics. Prevention includes good hygiene, prompt treatment of infections, and vaccination against Streptococcus pneumoniae.

Mycobacteria

Basic characteristics

Classification and types

• M. tuberculosis complex: Including M. tuberculosis (human tuberculosis), M. bovis (bovine tuberculosis), etc., which are the main pathogens of tuberculosis.
• Mycobacterium leprae (M. leprae): Causes leprosy.
• Non-tuberculous mycobacteria (NTM): Such as M. avium complex, M. kansasii, M. marinum, etc., which are mostly environmental bacteria, but can cause lung, skin or lymph node infections in people with low immune function.

Physiological and growth characteristics

Communication method

clinical impact

• Tuberculosis:Mainly caused by M. tuberculosis, it mainly affects the lungs and can also affect organs throughout the body.
• Leprosy:Caused by M. leprae, it affects the skin and peripheral nerves, possibly causing sensory loss and limb deformation.
• NTM infection:Immunosuppressed people are susceptible to infection, such as AIDS patients and organ transplant recipients, which may cause pneumonia, skin ulcers, etc.

Diagnosis and treatment

Prevention and control measures

Botulinum toxin

Basic characteristics

Clostridium botulinum is a Gram-positive, anaerobic, spore-forming rod-shaped bacterium. Its spores are extremely resistant to the environment and can survive in soil and water for a long time. The most important characteristic of this bacterium is its ability to produce botulinum toxin, which is considered one of the most powerful natural toxins known.

botulinum toxin

Botulinum toxin is a neurotoxin that blocks the release of acetylcholine from nerve endings, causing muscles to be unable to contract, thereby causing muscle paralysis. It is this characteristic that is used clinically to make "Botox" for medical treatment and beauty.

route of infection

• Foodborne:Eating canned or pickled foods that have not been adequately heated and contain spores.
• Traumatic:The wound is contaminated with spores, which produce toxins in an anaerobic environment.
• Baby type:The intestinal flora of infants is not fully developed, and spores can grow in the intestines and produce toxins. Honey is a common source.

clinical symptoms

The incubation period is usually 12 to 36 hours, and the main symptoms include:

• Blurred vision, double vision
• Difficulty swallowing and speaking
• Muscle weakness, which may lead to respiratory failure

medical applications

Botulinum toxin, which is highly purified and safely dosed, is widely used in:

• Treat muscle spasms (such as blepharospasm, torticollis)
• Relieve chronic migraines
• Wrinkle reduction in aesthetic medicine

Prevention and control methods

• Avoid canned foods from unknown sources or improperly preserved.
• Food needs to be heated enough to destroy the toxin (above 80°C for several minutes).
• Avoid honey in infants to prevent infantile botulism.
• Once infected, anti-toxin serum needs to be used promptly and respiratory support treatment provided.

Propionibacterium

Propionibacteria are a group of bacteria that are very present in biology and daily life. Their name comes from the main product of their metabolism: propionic acid. This group of bacteria are usually rod-shaped, Gram-positive bacteria, and have aerobic or anaerobic properties.

Metabolism and Swiss cheese

Propionibacteria are best known for their ability to ferment lactic acid or carbohydrates. During fermentation, they consume lactic acid and produce propionic acid, acetic acid, and carbon dioxide.

The chemical reaction process is as follows: lactic acid is converted into propionic acid, acetic acid, carbon dioxide and water. The released carbon dioxide bubbles form holes inside the cheese, which is where Swiss cheese’s signature look and special flavor come from.

Main representative species

Industrial application value

• Food Preservatives: Propionic acid has a natural antibacterial effect and is often used as a food preservative to prevent bread from becoming moldy.
• Nutritional synthesis: Propionibacterium species are important biological sources for the industrial production of vitamin B12.
• Medical research: The genome of Propionibacterium acnes has been sequenced, helping to develop targeted skin treatments.
• Probiotic development: Some studies explore their potential as probiotics to modulate intestinal flora.

Fungus

What are fungi?

Fungi are a large group of organisms composed of cellular nuclei, including yeasts, molds, and mushrooms. Fungi are distinctly different from plants, animals, and bacteria, have their own unique characteristics, and play important roles in ecosystems and human life.

Main features

• Alien creatures:It cannot produce nutrients through photosynthesis and relies on absorbing organic matter from the outside.
• Cell wall:The cell wall is mainly made of chitin, not the plant cellulose.
• Spore reproduction:Most fungi reproduce asexually or sexually through spores.
• Mycelium:The main body structure of a fungus is composed of hyphae, which are elongated, thread-like structures.
• Decomposer:Many fungi can decompose organic matter and participate in the material cycle of ecosystems.

Classification

Fungi are generally divided into the following main categories:

1. Ascomycota:Including yeast, Penicillium and Koji.
2. Basidiomycota:Including mushrooms, fungus and Ganoderma lucidum.
3. Zygomycota:Such as Mucor and Rhizopus.
4. Chytridiomycota:Mainly lives in water, often parasitizing or decomposing.

ecological role

Fungi play a variety of roles in ecosystems:

• Decomposer:Breaks down organic matter, releasing nutrients for plants to absorb.
• Symbiotic relationship:Form mycorrhizae with plant roots to share nutrients and promote plant growth.
• Parasite:Some fungi can infect plants or animals, causing disease.

Human applications

Fungi have important uses in human life:

• Food manufacturing:Such as used for brewing beer, making bread and fermented tofu.
• Drug production:Antibiotics such as penicillin are derived from fungi.
• Environmental protection:Used to treat pollutants such as broken down petroleum and plastics.

fungi evolution

Fungi

Basidiomycota
    Basidiomycetes
        Polypores
            Polyporaceae
                Antrodia Antrodia , Antrodia camphorata , Antrodia antrodia
            Ganoderma lucidum Ganoderma lucidum
        Auricularia black fungus, hairy fungus
    Tremella
        Tremella auricula White fungus
    Agaricomycetes
        Agariales
            Pleurotusaceae Pleurotus eryngii, Pleurotus eryngii (Golden cap mushroom/Golden mushroom/Coral mushroom), Pleurotus pleurotus (Pleurotus pleurotus)
            Apiaceae, Lentinus edodes (Winter mushroom/Northern mushroom/Flower mushroom/Shiitake mushroom), Flammulina velutipes
        Russales
            Hericaceae Hericium
        Dermatomales Phellinus linteum
        

Ascomycota
    Faecalimycetes
        Hypocarales
            Cordycepsaceae
                Cordyceps sinensis Cordyceps sinensis
    Discomycetes - order
            Truffleaceae - genus Truffle
Kingdom of Vesicola
    Unequal flagella
        Phaeophyceae Kelp/Kombu

Lichen

Basic characteristics

Main types

• scab-like lichen: Clings to rock or bark surfaces and looks like a thin layer of paint.
• leafy lichen: Spread out in sheets, often attached to rocks, soil or bark.
• dendritic lichen: In the shape of branches or shrubs, hanging from branches or rock walls.

Distributed environment

• Alpine rocks and bare earth
• Forest tree trunks and branches
• Arid or cold areas (such as deserts and polar regions)
• Urban environment (but sensitive to air pollution)

ecological function

• Environmental indicators:It is particularly sensitive to air quality and can be used as an air pollution monitoring indicator.
• Soil formation:It can break down rocks and promote soil formation.
• Nutrient cycle:Some lichens contain nitrogen-fixing blue-green bacteria, which aid in the nitrogen cycle.
• Ecological habitat:Provide living space for insects and microorganisms.

human use

• Source of dye:Certain lichens can extract natural dyes.
• Medicinal value:Some lichens contain antibacterial and anti-inflammatory properties.
• Edible use:For example, Cetraria islandica is used as food or medicine in some areas.

Little knowledge

• Lichens are not a single species, but symbionts.
• It grows extremely slowly and is often considered a long-lived creature.
• In polar and alpine ecosystems, lichens are major primary producers.

animal

branch of animal evolution

arthropods

What are arthropods?

Arthropoda is the most diverse and widely distributed group of animals on earth, including insects, spiders, crustaceans, and myriapods. Their bodies are exoskeletal and segmented, with articulated appendages.

Main features

• Exoskeleton:Made of hard chitin that protects the body and supports muscles.
• Segmented body:The body is divided into different segments, each with a specific function.
• Articulated appendages:For locomotion, touch, prey, or other specific functions.
• symmetry:Has a bilaterally symmetrical body structure.
• Open circulation system:Blood flows in body cavities rather than in closed blood vessels.

Classification

Arthropods are mainly divided into the following subphyla:

1. Insecta:Contains butterflies, mosquitoes, beetles, etc.
2. Arachnida:Including spiders, scorpions and ticks.
3. Crustacea:Such as shrimp, crab, krill, etc.
4. Myriapoda:Contains centipedes and millipedes.
5. Trilobita:Extinct marine arthropods.

importance

Arthropods play important roles in ecosystems and human life:

• As an important part of the food chain.
• Helps pollinate and maintain plant reproduction.
• Certain species can decompose organic matter and promote ecological recycling.
• They may also be disease transmitters, such as mosquitoes transmitting malaria.

Arthropod evolutionary branch

Arthropods - evolutionary branch

|
             +----------------------------------------------------------------+
             | |
           Dinosaurs: Dominated the Cambrian and became extinct in the Ordovician 540-480 million years ago True arthropods
                                                                         |
             +----------------------------------------------------------------+
             | |
          Arachnids Chelicerata Gnathostome Mandibulata
             | |
             +---------------------+ +----------------------+
             | | | |
          trilobites chelicerae pancrustaceans polypods
                                    spider, scorpion, horseshoe crab | centipede, millipede
                                                         +-------------+
                                                         | |
                                                       Hexapod: Insects Crustaceans: shrimps, crabs, barnacles
                                                         | |
300 million years ago - Beginning of the Permian - High Oxygen Age > Macroarthropods | |
                                             +-----------+ |
                                             | | |
                                        Pterygoid silverfish
                                             |
                                             +-----------+
                                             | |
                                         Archaeoptera Neoptera
                                             | |
                                  +----------+ +-----------+
                                  | | | |
                             Superorder Odonata, Mayflies, Eumetabolans, Neoptera
                               Dragonfly | |
                                             +-----------+ +----------+
                                             | | | |
                                           Cicada, endophytic wing, locust, louse, Dictyoptera
                                                         | Mantis Cockroach Termite
                                             +-----------+-------+
                                             | | |
                                          Scorpionoid order Coleoptera Hymenoptera
                                             | Beetle | 30M years ago
                                  +----------+ +----+
                                  | | | |
                               Butterfly, moth, flea, Diptera, broad-waisted, thin-waisted
                                             | bee ant
                                  +----------+
                                  | |
                              Longhorned flies
                                mosquito gnat midge

large branch of vertebrates

fish

What is fish?

Fish are a large group of vertebrates that mainly live in water and rely on gills for breathing. There are many types of fish and they are widely distributed, ranging from freshwater lakes to deep seas.

Main features

• Gill respiration:Use their gills to extract oxygen from the water.
• Fin structure:The fins on the sides and tail of the body are used for swimming and balance.
• Streamlined body:Reduces resistance in water and helps you swim quickly.
• Scale coverage:The bodies of most fish are protected by scales.
• Cold-blooded animals:The body temperature of fish changes with the ambient temperature.

Classification

Fish are usually divided into three major categories:

1. Chondrichthyes:Such as sharks, rays, etc., the skeleton is composed of cartilage.
2. Bony fish (Osteichthyes):For example, carp and goldfish have hard bones.
3. Jawless fish (Agnatha):Lampreys, for example, have no lower jaw and are among the most primitive fish species.

living environment

Fish live in a variety of aquatic environments, including:

• freshwater:Such as fish in rivers and lakes, such as carp and salmon.
• seawater:Fish that live in the ocean, such as cod and tuna.
• The junction of saltwater and freshwater:Certain fish species are adapted to saltwater, such as mudskippers and eels.

importance

Fish play an important role in human life and ecosystems:

• As an important source of protein, supporting the global food supply.
• A key part of the ecosystem that maintains aquatic biodiversity.
• Promote economic development, such as fisheries and ornamental fish farming.

Fish - clade

Vertebrates/Vertebrata
             |
             +-------------------------------------------------------------+
             | |
         Jawless: Hagfish, Lamprey Jawed (<4.5億年前):形成上下開合的口
                                                                        |
             +----------------------------------------------------------+
             |                                                          |
             |                                                      盾皮魚† 4.4~3.6億年前
             |
             +----------------------------------------------------------+
             |                                                          |
         硬骨魚                                                軟骨: 鯊魚 鰩 魟 鱝 電鰩
             |
             +----------------------------------------------------------+
             |                                                          |
         條鰭/幅鰭                                             肉鰭魚:骨頭伸到鰭端
             |                                                          |
             +-------------------+                                      +---------------------+
             |                   |                                      |                     |
         軟質亞綱            新鰭亞綱                          腔棘魚綱, 肺魚        四足/Tetrapods: 肉鰭魚上陸
             鱘                  |                    
                                 |                    
             +-------------------+                    
             |                   |                    
         真骨下綱            全骨下綱: 雀鱔 弓鰭魚
             |
             +-------------------+
             |                   |
        龍魚 鰻 海鰱		   鯡頭魚
                                 |                    
             +-------------------+                    
             |                   |
           正真骨魚群          骨鯡群
             |                      鯉 沙丁魚 鯰 鯡 鯷
             |
             +-------------------+
             |                   |
            鮭 狗魚 香魚       新真骨魚亞群
                                 |                    
             +-------------------+                    
             |                   |
         鱸形亞類               鱈 燈籠魚 皇帶魚 月魚
             |
             +-------------------+
             |                   |
          鮪 鯖 鰹               |                    
                                 |                    
             +-------------------+                    
             |                   |
          真鱸形Eupercaria       +------------+
           鱸 鯛                 |            |
                    +------------+          卵附系
                    |            |             飛魚 秋刀魚
                鰺形系         攀鱸系
                   旗             攀鱸 鰻鰍

placoderm

Overview

Morphological characteristics

• Bone carapace:The cephalothorax is covered with thick bony plates to provide protection.
• Teethless jaw:There are bony bite plates on both sides of the mouth, which are not actual teeth.
• Endochondral skeleton:The internal skeleton of the body is mainly composed of cartilage, similar to that of today's cartilaginous fish.
• Tail and body shape:The tail usually has fins, and its shape varies greatly depending on the species. The body size ranges from several centimeters to several meters.

Classification

• Order Arthrodira:It is the most numerous group of placoderms, with representatives such as Dunkleosteus having movable cephalothorax joints.
• Antiarchi:They are smaller in size and have well-developed forelimb fins, which help them crawl underwater, such as Bothriolepis.

ecological role

• Small placoderms are mostly bottom dwellers and filter feed on microorganisms or humus.
• Large placoderms such as Dunkirk are the top predators in the sea and feed on other fish.

extinct

evolutionary significance

representative fossil

• Dunkleosteus：It can reach up to 6 meters in length and has a strong bite. It was the predatory overlord of the prehistoric oceans.
• Bothriolepis：With a body length of about 30 centimeters and a wide distribution, it is a key species for studying the diversity of placoderms.

Conclusion

The difference between the Chlamydophyllum sect and the Round scale sect

Basic classification

• Chlamydia sect:Including acanthus and some deep-sea fish, such as tuna, seahorse, grouper, etc.
• Round scale faction:It mainly includes lizard fishes, such as hairtail fish, naked head fish, etc., which are relatively primitive teleost fishes.

scale pattern

• Chlamydia sect:The edges of the scales have a serrated structure called ctenophores.
• Round scale faction:The scales have smooth edges and a round structure, called round scales.

evolutionary position

• Chlamydia sect:It is an evolutionarily advanced group and is the core of the diversification of modern spiny-finned fishes.
• Round scale faction:It is an earlier differentiated lineage, close to the base of the teleost fish evolutionary tree.

Morphological characteristics

• Chlamydia sect:The jaw and skull structures are well developed, and the swimming ability and hunting methods are diverse.
• Round scale faction:The bone structure is relatively simple, and many species are adapted to life in the deep sea.

System Classification Controversy

• Some studies believe that the Sauroptera belongs to two factions at the same time, making the Round Scale faction possible not to be a monophyletic group.
• According to molecular phylogenetic analysis, the ctenophyte forms a monophyletic group, including sauropsids and acanthopterygians.

English name note

Ctenosquamata, Cyclosquamata

Brief comparison table

Trevally type

Classification status

The Trevally lineage is an evolutionary branch of the Acanthopterygii class, belonging to the Ctenophora group, and includes many important medium and large marine predatory fishes, and is part of the Perciform lineage.

representative species

• Carangidae: such as jack mackerel, yellowfin trevally, and crane slug
• Istiophoridae: such as swordfish
• Xiphiidae: such as swordfish

Morphological characteristics

• The body shape is mostly streamlined, with a slender caudal peduncle and a crescent-shaped caudal fin.
• Good at high-speed swimming and strong muscle structure
• The snout is long and pointed, and some species have a beak-like extended upper jaw.

ecological characteristics

• It inhabits tropical and temperate oceans and is distributed from near shore to open ocean.
• It is a predatory fish, preying on fish, cephalopods, etc.
• Mostly highly migratory species

Comparison with similar fish groups

Differences from Climbing Bass System

• Anabantaria are mainly found in freshwater waters
• A labyrinth organ that can breathe air and adapt to hypoxic environments
• Representative fish species such as climbing bass, fighting fish, thunder fish, etc.
• The trevally type is a high-speed predatory fish that is fully adapted to ocean migration.

Differences from egg attachment

• Most members of Ovalentaria are fish that lay sticky eggs
• There are many reproductive behaviors, and it is common for parents to protect eggs, such as cichlids, damselfish, etc.
• Live mostly in coral reefs or coastal environments
• The eggs of the trevally type are mostly floating eggs with no egg-guarding behavior and live in open waters.

Differences from true perch

• Percomorphacea is the largest branch of acanthus fishes
• Contains multiple branches such as the trevally type system, the climbing perch system, and the egg attachment system.
• The trepanform lineage is a clear clade that is adapted to high-speed marine predation.
• There are obvious differences from other branches such as benthic, coral reef, and freshwater adapted species.

Common misunderstandings

• Although fish from the family Scombridae are similar to the scombridae and are also high-speed swimmers, they are actuallyScombroids, does not belong to the trevally type.

Evolution and Systemic Relationships

• The Trevally family is part of the Ctenoides family and evolved from within the True Perch family.
• Based on molecular genetic analysis, it is a highly specialized migratory predatory group.

Fisheries and Economic Value

• Trevally, swordfish, swordfish, etc. are important economic fish species
• It has high commercial value and is widely used in fresh food, canned food, and ocean fisheries.
• It is also the main target for recreational fishing and competitive fishing and hunting.

mackerel

Classification and morphological characteristics

Mackerel (scientific name:ScomberGenus) belongs to the class Actinopterygii, order Scombridae, family Scombridae. The body is spindle-shaped, with a smooth body surface, a blue-green back with dark ripples, and a silver-white belly. The body length is generally between 20 and 40 centimeters. Its muscles are rich in oil and it swims fast. It is a typical migratory fish.

Types of Mackerel

Mackerel includes a variety of closely related fish, which can be distinguished according to their distribution areas and body color patterns as follows:

• Japanese Mackerel (Scomber japonicus): Also known as flower mackerel or blue mackerel, it is widely distributed in the northwest Pacific and is the main edible mackerel common in Taiwan and Japan. There are wavy lines on the back and slight spots on the abdomen.
• Atlantic mackerel (Scomber scombrus): Also known as true mackerel or northern mackerel, it is distributed in the North Atlantic and European coasts. It has obvious lines on the side of the body, firm meat and medium oil content.
• Scomber australasicus: Distributed near the South Pacific, Australia and New Zealand, it looks similar to Japanese mackerel but has lighter body lines and a silvery white belly.
• Indian Mackerel (Rastrelliger kanagurta): Also known as short mackerel or Indian mackerel, it is distributed in the Indian Ocean and Southeast Asian waters. It has a slightly shorter body and black horizontal spots on its back.
• White-bellied mackerel (Scomber australasicus subspecies): Distributed in the southern seas of Taiwan and Japan, the belly is white and spotless, with high fat content and soft meat, suitable for grilling.
• Scomber japonicus subspecies: There are small black spots or patterns on the abdomen, the oil is slightly less than that of white-bellied mackerel, and the flavor is light. It is commonly caught in spring and summer.

Habitat

Mackerel inhabits temperate and subtropical waters and likes water temperatures of 15 to 25°C. It is a typical pelagic migratory fish. Mainly distributed in the North Pacific, North Atlantic, Mediterranean and Indian Oceans, they often migrate in groups and move with the seasons.

Ecology and habits

Mackerel feeds on plankton, small fish and crustaceans, and has the characteristics of swimming in schools and at high speeds. The breeding season is mostly in spring and summer. Female fish can lay hundreds of thousands of floating eggs at a time. They grow rapidly after hatching and are an important link in the marine food chain.

nutritional value

Mackerel is rich in Omega-3 fatty acids (EPA, DHA), protein, vitamin D and B complex, which can help lower cholesterol, promote brain development and fight inflammation. Fats are mainly unsaturated fatty acids, which are extremely beneficial to cardiovascular health.

How to eat

Common dishes include salt-grilled mackerel, miso-boiled mackerel, smoked mackerel, pan-fried mackerel, or canned mackerel. Because it is rich in oil and is prone to oxidation and deterioration, it needs to be kept refrigerated and protected from prolonged exposure to the sun.

economic and cultural significance

Mackerel is one of the world's most important economic fish species, and is fished and exported in large quantities by Japan, Norway, Iceland and Taiwan. Mackerel is popular in Japanese, Korean, Mediterranean and Taiwanese diets and is regarded as an affordable and nutritious marine food.

A fish that looks similar to mackerel

Overview

Many fish are similar in appearance to mackerel, such as slender bodies, silvery-blue luster, and stripes or spots on their backs. However, they are not taxonomically classified as Scombriformes, but belong to other fish families or orders. Listed below are several fish species that are often mistaken for mackerel.

Similar fish species

• Sardines (Sardinops melanostictus)

  It belongs to the family Clupeidae of the order Clupeiformes. It has a slender body and a silvery white color, with a slight blue-green sheen on its back. Although its body color is similar to that of mackerel, its scales are obvious and its surface is rough, so it is often mistaken for young mackerel.

• Cololabis saira

  It belongs to the family Scomberesocidae of the order Beloniformes. It has a slender body shape, a pointed mouth, a blue-black back, and a silvery white abdomen. Because its body color is similar to that of mackerel and it is also rich in oil, its appearance is easily confused.

• Horse mackerel (Trachurus japonicus)

  It belongs to the family Carangidae of the order Carangiformes, and is also known as the carp fish. The body is spindle-shaped, with a blue-green back and silvery white belly. It is very similar to mackerel, but has larger eyes and hard scales on the tail peduncle.

• Euthynnus affinis

  Belongs to the family Scombridae but belongs to the genus Scomber, an atypical genus. It is larger in size, with a blue-black back and black stripes on its belly. It is often mistakenly called "big mackerel".

• Flying fish (Exocoetus volitans)

  It belongs to the family Exocoetidae of the order Beloniformes. It has bright silver sides and a blue-black back. It looks similar to mackerel, but its pectoral fins are specialized into gliding wing-like structures. Its ecology and habits are very different.

• Scomberomorus niphonius

  It belongs to the family Scomberoideae but belongs to the genus Scomberomorus, not the genus Scomberomorus. It has a slender body and dark horizontal spots on its back. It is often called "Mackerel mackerel", but it is classified differently from mackerel.

Identify the important points

Although these fish are similar in appearance, the typical characteristics of mackerel include a smooth body surface, a rippled back, no obvious lateral scales, a narrow caudal peduncle, and small fins. If it has large scales, hard lateral line scales or special fin structure, it usually does not belong to the order Scombridiformes.

mammalian evolutionary branch

Sauromorpha clade

Convergent evolution into snake-like animals

definition

• Convergent evolution into serpentine shape: refers to the fact that animals from different evolutionary branches independently evolved forms with elongated bodies, extended trunks, and degenerated limbs under similar environmental pressures (such as burrowing into the ground, passing through slits, and swimming).

Main examples (including evolutionary categories)

• Serpentes — Reptiles Reptilia → Squamata → Serpentes
  A typical snake-like vertebrate with complete loss of limbs and highly specialized jaws and body.
• Earthworm (Amphisbaenia) — Reptiles Reptilia → Squamata → Amphisbaenia
  Burrowing lizards have segmented bodies, extremely degenerated eyes, and most have no legs.
• Legless lizard (evolved independently multiple times)
  • Skink family Scincidae—Reptiles → Squamata → Skinkidae
  • Pygopodidae—Reptiles → Squamates → Basilisks (close relatives: skinks)
  It looks like a snake, but retains lizard characteristics such as eyelids and part of the external ear holes.
• Glass lizard (Ophisaurus and other basilisks) — Reptiles → Squamates → Anguidae
  Like a snake but a lizard, it has a long tail that can cut itself off and a lizard-like skull.
• Anguilliformes — Teleost Actinopterygii → Anguilliformes
  An example of an aquatic serpentine, with an extremely elongated body and no pelvic fins.
• Caecilians — Amphibia → Gymnophiona
  A completely limbless amphibian, living in the soil or humus layer, and highly snake-like in appearance.

Birds clade

pet

definition

Pets refer to animals kept by humans for companionship, entertainment or emotional sustenance. They are usually docile and tameable and can establish interactive relationships with people.

Common types

• dog:Loyal and lively, it is often used as a companion and guardian animal.
• cat:Highly independent, common in urban families, able to establish close relationships with others.
• birds:Such as parrots and munia, which have the characteristics of singing or copying.
• Fish:It is highly ornamental, such as goldfish and tropical fish, and is suitable for static appreciation.
• Small mammals:Such as rabbits, guinea pigs, and hamsters, which are small in size and require less space for breeding.
• Reptiles and other special pets:Such as turtles, snakes, and lizards, suitable for owners who are interested in special animals.

Breeding purpose

• Emotional support and companionship
• Entertainment and Leisure
• Education and responsibility development
• Some pets have functional functions, such as guide dogs and therapy dogs

Feeding instructions

• Provide suitable food and clean water
• Maintain a clean environment and adequate space for activities
• Regular health check-ups and vaccinations
• Provide care and interaction to avoid isolation

social and cultural significance

Pets play an important role in human culture, not only as part of the family, but also by promoting mental health, reducing loneliness, and even playing a healing role in animal-assisted therapy.

Interesting facts

Archaeological evidence shows that humans began to domesticate dogs as companions more than 10,000 years ago, and they were the earliest pets.

biological senses

definition

Biological senses are systems used by organisms to sense changes in the external and internal environment. They receive stimuli through specialized sensory organs and transmit the signals to the nervous system for processing and response.

Main sense types

• Vision:The eyes are mainly responsible for perceiving light and images.
• Hearing:The ears are mainly responsible for sensing sounds and vibrations.
• Smell:The perception of odor molecules is accomplished through olfactory cells in the nasal cavity.
• Taste:The chemical components in food are identified through the taste buds on the tongue.
• Touch:Senses pressure, temperature and pain through the skin and other sensory neurons.

other senses

• Sense of balance:The vestibular system of the inner ear senses body position and dynamic balance.
• Proprioception:Perceive the position and movement status of various parts of the body.
• Magnetic sense:Some animals, such as migratory birds and turtles, can sense the geomagnetic field to navigate.
• Infrared sensing:Snakes, for example, can sense infrared heat emitted by their prey.

importance of senses

Senses are key to biological survival and interaction, helping to sense danger, find food, reproduce, and communicate with other organisms in the environment.

sense of smell

definition

Olfaction is the ability of humans and animals to perceive odors through olfactory receptors in the nasal cavity to identify various molecules in the air.

Operating mechanism

When odor molecules enter the nasal cavity, they come into contact with olfactory epithelial cells. These cells transmit signals to the olfactory bulb, which then sends the information to the olfactory cortex area of ​​the brain for processing and recognition.

function of smell

• Identify whether food is fresh or spoiled
• Be alert to dangerous gases (such as smoke or gas)
• Strengthen the connection between emotions and memory
• Used as a social or courtship signal among animals

Smell and health

Decreased ability to smell may be a sign of aging, infection (such as the common cold or coronavirus), or neurodegenerative diseases (such as Parkinson's disease, Alzheimer's disease).

Interesting facts

Humans can identify more than 10,000 odors; however, each person's sensitivity to odors is different, which is related to genetic makeup and life experience.

hot sensation

definition

Hot sensation is a subtype of touch and belongs to the temperature sensation. It is mainly the human body's feeling of high temperature stimulation. When the skin comes into contact with an object that is too hot, it will immediately produce a burning or stinging sensation, warning of potential danger.

Perception mechanism

There are specialized temperature receptors (thermal receptors) and pain receptors in the skin. When exposed to a heat source exceeding about 42°C, the thermal receptors and pain receptors will be activated at the same time, and the signals will be transmitted through the nerves to the spinal cord and the somatosensory cortex of the brain for interpretation.

Physiological function

• Protect the body from burns or tissue damage
• Quickly initiate reflex actions (such as quickly removing your hand)
• Participate in temperature regulation and environmental adaptation

Association with other senses

The sensation of heat is closely related to the sensation of pain. Excessive temperature is usually interpreted by the brain as "pain" rather than simply "heat". In addition, the sense of hotness also participates in the judgment and balance of the temperature range together with the sense of coldness.

Common applications

• Sensing water or food temperature to avoid burns
• Abnormal reaction heat source (such as overheating of electrical appliances)
• Medical testing of touch and nerve function

The spicy and hot feeling of chili pepper

The "spiciness" you feel when eating chili peppers is actually not a sense of taste, but a combined experience of pain and heat. This feeling comes from capsaicin, the active ingredient in chili peppers.

The role of the TRPV1 receptor

TRPV1 (Transient Receptor Potential Vanilloid 1) is a type of receptor found in nerve endings, responsible for detecting high temperature and chemical stimuli. When the skin or mouth comes into contact with a heat source exceeding approximately 42°C, TRPV1 is activated, causing a sensation of burning and pain.

Capsaicin can directly bind to TRPV1 and induce a neural response similar to that of a burn. Although there is actually no increase in temperature, it tricks the brain into thinking it is exposed to high temperatures, resulting in a burning or tingling sensation.

physiological significance

• Warning system: TRPV1 helps the body respond quickly to high temperatures or harmful substances to avoid tissue damage.
• Pain Modulation: Prolonged or repeated stimulation of TRPV1 (e.g., continued eating spicy food) can desensitize the nerve, reducing pain sensitivity.
• Medical applications: Capsaicin has been formulated into topical ointments to relieve chronic pain such as arthritis and neuralgia.

fun facts

TRPV1 in some animals, such as birds, is not activated by capsaicin, so they can easily eat peppers without feeling the heat, which also helps plants disperse their seeds.

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