Keynote lectures/Zoology

From Wikiversity
Jump to navigation Jump to search
The image shows a full length view of an adult blue whale. Credit: NOAA Fisheries (TBjornstad).

Zoology is a biological science that pertains to animals.


Genetics is the study of the genes, how they affect organisms, and how they are passed from one generation to the next. A scientist that studies genetics is called a geneticist.

DNA, deoxyribonucleic acid, is a molecule found in almost every cell of every body of every organism. DNA contains genes, which are the basic instruction codes for making and running a living organism. Strands of DNA make up chromosomes. (Chromosomes are made of DNA, which is made up of genes.)

Genes, through DNA and chromosomes, are passed from one generation to the next by inheritance. Because of this, offspring resemble their parents. Through mixing and occasional mutation, genes can change. When genes change, how the organism forms and how it works may be changed.

How all these changes affect individuals, populations, and entire species is the work of geneticists. ______

"A recent comparison of the draft sequences of mouse and human genomes has shed light on the selective forces that have predominated in their recent evolutionary histories. In particular, mouse-specific clusters of homologues associated with roles in reproduction, immunity and host defence appear to be under diversifying positive selective pressure, as indicated by high ratios of non-synonymous to synonymous substitution rates. These clusters are also frequently punctuated by homologous pseudogenes. They thus have experienced numerous gene death, as well as gene birth, events. These regions appear, therefore, to have borne the brunt of adaptive evolution that underlies physiological and behavioural innovation in mice. We predict that the availability of numerous animal genomes will give rise to a new field of genome zoology in which differences in animal physiology and ethology are illuminated by the study of genomic sequence variations."[1]


This image is a drawing of Haloquadratum walsbyi. Credit: Rotational.

Def. the "study of all life or living matter"[2] is called biology.

On the right is a drawing of the archaean Haloquadratum walsbyi.

As the study of biology is the study of all living organisms, zoology is a specialty of biology. All zoologists are also considered biologists.

Other branches of biology include botany (the study of plants), mycology (the study of fungi), phycology (the study of algae), and virology (the study of viruses).


The biological definition of animals includes all members of the kingdom Animalia.[3]

In colloquial use, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals.[4][5][6][7]

Animals are eukaryotic and multicellular,[8][9] unlike bacteria, which are prokaryotic, and unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which are autotrophs, producing their own nutrients[10] animals are heterotrophic,[9][11] feeding on organic material and digesting it internally.[12] With very few exceptions, animals breathe oxygen and respire aerobically.[13] All animals are motile[14] (able to spontaneously move their bodies) during at least part of their life cycle, but some animals, such as sponges, corals, mussels, and barnacles, later become sessile. The blastula is a stage in embryogenesis, embryonic development, that is unique to most animals,[15] allowing cells to be differentiated into specialised tissues and organs.

All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins.[16] During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible. This may be calcified, forming structures such as an exoskeleton of shells, bones, and spicules.[17] In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth.[18] Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes.[19]

With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues.[20] These include muscles, which enable locomotion, and nerve tissues, which transmit signals and coordinate the body. Typically, there is also an internal digestive chamber with either one opening (as in flatworms) or two openings (as in deuterostomes).[21]

Nearly all animals make use of some form of sexual reproduction.[22] They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova.[23] These fuse to form zygotes,[24] which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge.[25] In most other groups, the blastula undergoes more complicated rearrangement.[26] It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm.[27] In most cases, a third germ layer, the mesoderm, also develops between them.[28] These germ layers then differentiate to form tissues and organs.[29]

Repeated instances of inbreeding, mating with a close relative, during sexual reproduction generally leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits.[30][31] Animals have evolved numerous mechanisms for inbreeding avoidance, or avoiding close inbreeding.[32] In some species, such as the splendid fairywren (Malurus splendens), females benefit by mating with multiple males, thus producing more offspring of higher genetic quality.[33]

Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. This may take place through fragmentation; budding, such as in Hydra and other cnidarians; or parthenogenesis, where fertile eggs are produced without mating, such as in aphids.[34][35]

Animals are categorised into ecological groups depending on how they obtain or consume organic material, including carnivores, herbivores, omnivores, detritivores,[36] and parasites.[37] Interactions between animals form complex food webs. In carnivorous or omnivorous species, predation is a consumer-resource interaction where a predator feeds on another organism (called its prey).[38] Selective pressures imposed on one another lead to an evolutionary arms race between predator and prey, resulting in various anti-predator adaptations.[39][40] Almost all multicellular predators are animals.[41] Some consumers use multiple methods; for example, in parasitoid wasps, the larvae feed on the hosts' living tissues, killing them in the process,[42] but the adults primarily consume nectar from flowers.[43] Other animals may have very specific feeding behaviours, such as hawksbill sea turtles that primarily eat sponges.[44]

Most animals rely on the energy produced by plants through photosynthesis. Herbivores eat plant material directly, while carnivores, and other animals on higher trophic levels, typically acquire energy (in the form of reduced carbon) by eating other animals. The carbohydrates, lipids, proteins, and other biomolecules are broken down to allow the animal to grow and to sustain biological processes such as locomotion.[45][46][47] Animals living close to hydrothermal vents and cold seeps on the dark sea floor do not depend on the energy of sunlight.[48] Rather, archaea and bacteria in these locations produce organic matter through chemosynthesis (by oxidizing inorganic compounds, such as methane) and form the base of the local food web.[49]

Animals originally evolved in the sea. Lineages of arthropods colonised land around the same time as land plants, probably between 510–471 million years ago during the Late Cambrian or Early Ordovician.[50] Vertebrates such as the Sarcopterygii, lobe-finned fish, Tiktaalik started to move on to land in the late Devonian, about 375 million years ago.[51][52] Animals occupy virtually all of earth's habitats and microhabitats, including salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of animals, plants, fungi and rocks.[53] Animals are however not particularly heat tolerant; very few of them can survive at constant temperatures above 50 °C (122 °F).[54] Only very few species of animals (mostly nematodes) inhabit the most extreme cold deserts of continental Antarctica.[55]

Theoretical zoology[edit]

Def. "that part of biology which relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct"[56] is called zoology.


Zoography is descriptive zoology. Animals are described in comparison with other organisms, and their surroundings. This comparison takes into account variation among individuals and populations, and organizes it into systems and classifications that are used for making predictions, such as the evolutionary relationships among organisms.

The branches of zoology focusing on a particular taxonomic group (mammals, etc.) are often considered part of zoography.

Vertebrate Zoology[edit]

Vertebrate zoology is the study of vertebrates, the animals that have a spinal column. This covers only about 3% of all known species.


A malayan tiger is a mammal. Credit: B_cool from Singapore.

Def. the "study of mammals"[57] is called mammalogy.

Scientists who study mammalogy are called mammalogists.

Mammals are endothermic vertebrates that have fur or hair and feed milk to their young. Milk is a fluid produced by mammary glands.

There are about 5000 species of living mammal known to science. Mammals live in every habitat on Earth. They range in size from the Etruscan shrew (Suncus etruscus), the smallest living mammal, to the blue whale (Balaenoptera musculus) which is the largest animal to have ever lived. Humans (Homo sapiens) are also mammals. They are placed in the taxonomic class Mammalia.

External Resources:


Accipiter striatus venator is the Puerto Rican sharp-shinned hawk. Credit: U.S. Fish and Wildlife Service Southeast Region.

Def. "the scientific study of birds"[58] is called ornithology.

Scientists who study ornithology are called ornithologists.

Birds are endothermic vertebrates that have feathers and lay eggs. Birds are considered the only living direct descendants of dinosaurs. They belong to the taxonomic class Aves.

There are about 10,000 species of living bird known to science. Birds live in every habitat on Earth. They range in size from the Bee Hummingbird (Mellisuga helenae), the smallest living bird, to the Common Ostrich (Struthio camelus), which standing up to 8 feet (2.4 m) tall, is the tallest living bird.

External Resources:


This mounted specimen of Apatosaurus louisae is in the Carnegie Museum. Credit: Tadek Kurpaski from London, Poland.

Def. "branch of paleontology that focuses on studying dinosaurs"[59] is called dinosaurology.

Usually allied with geology rather than biology, paleontology is the study of past life. Dinosaurology is the specific branch of paleontology that is the study of dinosaurs. Because birds are the living descendants of dinosaurs, ornithology might be considered a branch of dinosaurology.

Scientists who study dinosaurs are usually called paleontologists, but might also be called dinosaurologists.

The non-avian dinosaurs lived during the Mesozoic Era, the time period between roughly 252 and 65 million years ago. The first dinosaurs evolved about 225 million years ago, and all but the birds became extinct by the end of the Mesozoic Era.

Dinosaurologists, like other paleontologists need a good grounding in geology and anatomy, as well as whatever other fields their particular study may involve.


The tuatara is a modern dinosaur. Credit: Knutschie.

Def. the "branch of biology dealing with reptiles (Reptilia) and amphibians"[60] is called herpetology.

Scientists who study herpetology are called herpetologists.

Reptiles and amphibians are ectothermic vertebrates that have scales or naked skin. Reptiles lay shelled eggs or give birth to live young. Amphibians lay eggs without shells.

There are about 8000 species of living amphibian known to science, and more than 10,000 species of reptile.

Amphibians live in every terrestrial habitat on Earth except in the arctic and antarctic. Amphibians are also absent from marine environments. The amphibians comprise the taxonomic class Amphibia. The living amphibians include frogs and toads, salamanders and newts, and caecilians.

Reptiles also live in every terrestrial habitat on Earth except the artic and antarctic, but some species also occur in marine environments. Reptiles comprise the taxonomic class Reptilia. The living reptiles include lizards, snakes, tuataras, crocodilians, and turtles.

External Resources:


The red milk snake is an ophiid. Credit: BillC.

Def. the "study of snakes"[61]is called ophiology.

Ophiology is a specialization of herpetology. Scientists who study ophiology are called herpetologists.

The name of this specialty comes from the Greek word for snake, ophis.


Bufo periglenes is the golden toad. Credit: Charles H. Smith.

Def. the "study of amphibians"[62] is called batrachology.

Batrachology is a specialty within herpetology. Scientists who study Batrachology are called herpetologists.

The name of this specialty comes from the Ancient Greek word for frog, batrakhos.


A preserved coelacanth (Latimeria chalumnae) and its pup at the Sant Hall of Oceans at the Smithsonian Museum of Natural History in Washington, D.C., USA. Credit: Tim Evanson.

Def. "the study of fish"[63] is called ichthyology.

Scientists who study ichthyology are called ichthyologists.

Fishes are endothermic vertebrates that live in the fresh or marine water.

Living species are extremely diverse, and belong to three taxonomic groups, Superclass Agnatha (jawless fishes), Class Chondrichthyes (sharks and rays), and the Osteichthyes (the bony fishes).

There are about 30,000 species of living fish known to science. Fish live in every aquatic habitat on Earth.

About the Photo: Considered a "living fossil" because it is an ancient class of lobe-limbed fish that otherwise went extinct more than 70 million years ago, the first living coelacanth was caught off the east coast of South Africa near the Chalumna River in 1938. Today, at least two major populations of coelacanths are known: one off east Africa, and another near Indonesia. Coelacanths cannot be eaten; their flesh contains an oil that is highly distasteful to human beings. This specimen in the image above weighs 160 pounds (72.6 kg) and measures 5.5 feet (1.67 m) in length.

See also: Fish

External Resources:

Invertebrate Zoology[edit]

Invertebrate zoology is the study of animals that lack a spinal column. This covers approximately 97% of all known living species.


Crinoid on the reef of Batu Moncho Island is near Komodo, Indonesia. Credit: Alexander Vasenin.

Def. study of the echinoderms is called echinodermology.

Echinodermology is a specialty of invertebrate zoology that studies echinoderms. The echinoderms include sea stars, urchins, and crinoids. All species are marine, so this is also a specialty of marine biology. Scientists who study echinoderms most often are called either marine biologists or invertebrate zoologists.


Entomology is the study of insects. Scientists who study entomology are called entomologists.


This is a natural image of Callioratis grandis. Credit: Bruce Byers.

Def. the "scientific study of butterflies and moths"[64] is called lepidopterology.

On the right is an example of Callioratis grandis from Mulanje Mountain, Africa.

Lepidopterology is the study of the Lepidoptera, the group of insects that includes butterflies and moths. It is a specialty of entomology, which is the overall study of insects. Most scientists who study the lepidoptera consider themselves to be entomologists.


Arachnology is the study of spiders, scorpions, and related arthropods. Scientists who study arachnology are called arachnologists.


This is an image of a female Latrodectus tredecimguttatus. Credit: K. Korlevic.{{free media}}
This is an image of a male Latrodectus tredecimguttatus. Credit: K. Korlevic.{{free media}}

Def. the "study of the spider, a branch of arachnology"[65] is called araneology.


The "Acanthocephala, are descended from, and should be considered as, highly modified rotifers. Genetic research has determined this is unequivocal; the Acanthocephalans are modified rotifers".[66] ______________

Parasitology is the study of parasites. In this context, a parasite is usually an invertebrate, and as such parasitology is a specialization of invertebrate zoology. Scientists that study parasites are called parasitologists.

Parasites are organisms that live on or in, and take their nutrition from, another living organism called a host. Rarely do parasites kill their hosts, since finding a new host can be quite difficult. Individual parasites may do little harm to their host, but large numbers of them can cause great problems. This kind of relationship where one organism lives off another giving either nothing in return or causing harm is called parasitism.

Parasites may be found in many invertebrate taxonomic groups. Commonly encountered parasites include tapeworms, roundworms, and lice.

Systematics & Taxonomy[edit]

A collage depicts animal diversity using a collection of featured pictures. Credit: Justin.

Superregnum: Eukaryota[67]

Systematics is the study of the evolutionary relationships among organisms. It includes taxonomy, which is the study of the names of organisms and their organization into categories. Scientists who study systematics are called systematists, while taxonomists primarily study taxonomy. Most systematists are also taxonomists.

Living organisms are grouped into a hierarchy of categories. The main categories are Kingdom (or Regnum, pl. Regna), Phylum (pl. Phyla), Class, Order, Family, Genus (pl. Genera), and Species (pl. Species). Every living organism is classified into one, and only one, of each of those categories. There are additional categories used for some groups, but not all.

The classification of organisms can change as more is learned about the living world around us.

Below are two ideas of how life may be divided into Kingdoms (Regna).

  • Four Regna listed by Whittaker & Margulis (1978): Animalia - Plantae - Fungi - Protista
  • Five Regna listed Cavalier-Smith (1981): Animalia - Plantae - Fungi - Chromista - Protozoa

Below is one recent list of the Phyla of within the Kingdom Animalia. Note number 8, Chordata. That is the Phylum that includes vertebrates, the animals with a spinal column that includes humans.

Regnum: Animalia Phyla (36):

  1. Acanthocephala
  2. Annelida
  3. Arthropoda
  4. Brachiopoda
  5. Bryozoa
  6. Cephalorhyncha
  7. Chaetognatha
  8. Chordata
  9. Cnidaria
  10. Ctenophora
  11. Cycliophora
  12. Echinodermata
  13. Echiura
  14. Gastrotricha
  15. Gnathostomulida
  16. Hemichordata
  17. Kamptozoa
  18. Kinorhyncha
  19. Loricifera
  20. Micrognathozoa
  21. Mollusca
  22. Myxozoa
  23. Nematoda
  24. Nematomorpha
  25. Nemertea
  26. Onychophora
  27. Orthonectida
  28. Phoronida
  29. Placozoa
  30. Platyhelminthes
  31. Porifera
  32. Rhombozoa
  33. Rotifera
  34. Sipuncula
  35. Tardigrada
  36. Xenacoelomorpha


An hypothesis is a scientific statement made to explain some part of the world. It is not a guess. It is testable by scientific means, and is falsifiable (able to be disproved) by those means. Coming up with hypotheses and testing them are the main occupation of science.

  1. The genetic classification of animals may not match the current classification before genetic evidence.

See also[edit]


  1. Richard D. Emes, Leo Goodstadt, Eitan E. Winter and Chris P. Ponting (2003). "Comparison of the genomes of human and mouse lays the foundation of genome zoology". Human Molecular Genetics 12 (7): 701-9. doi:10.1093/hmg/ddg078. Retrieved 2014-05-18. 
  2. biology. San Francisco, California: Wikimedia Foundation, Inc. 23 February 2015. Retrieved 2015-02-23.
  3. Animal, In: The American Heritage Dictionary (4th ed.). Houghton Mifflin Company. 2006.
  4. animal, In: English Oxford Living Dictionaries. Retrieved 26 July 2018.
  5. Boly, Melanie; Seth, Anil K.; Wilke, Melanie; Ingmundson, Paul; Baars, Bernard; Laureys, Steven; Edelman, David; Tsuchiya, Naotsugu (2013). "Consciousness in humans and non-human animals: recent advances and future directions". Frontiers in Psychology 4: 625. doi:10.3389/fpsyg.2013.00625. PMID 24198791. PMC 3814086. // 
  6. The use of non-human animals in research. Retrieved 7 June 2018.
  7. Nonhuman definition and meaning | Collins English Dictionary. Collins. Retrieved 7 June 2018.
  8. Avila, Vernon L. (1995). Biology: Investigating Life on Earth. Jones & Bartlett Learning. pp. 767–. ISBN 978-0-86720-942-6.
  9. 9.0 9.1 Palaeos:Metazoa. Retrieved 25 February 2018.
  10. Davidson, Michael W. Animal Cell Structure. Retrieved 20 September 2007.
  11. Bergman, Jennifer. Heterotrophs. Retrieved 30 September 2007.
  12. Douglas, Angela E.; Raven, John A. (January 2003). "Genomes at the interface between bacteria and organelles". Philosophical Transactions of the Royal Society B 358 (1429): 5–17. doi:10.1098/rstb.2002.1188. PMID 12594915. PMC 1693093. // 
  13. Mentel, Marek; Martin, William (2010). "Anaerobic animals from an ancient, anoxic ecological niche". BMC Biology 8: 32. doi:10.1186/1741-7007-8-32. PMID 20370917. PMC 2859860. // 
  14. Saupe, S. G. Concepts of Biology. Retrieved 30 September 2007.
  15. Minkoff, Eli C. (2008). Barron's EZ-101 Study Keys Series: Biology (2nd, revised ed.). Barron's Educational Series. p. 48. ISBN 978-0-7641-3920-8.
  16. Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter (2002). Molecular Biology of the Cell (4th ed.). Garland Science. ISBN 978-0-8153-3218-3.
  17. Sangwal, Keshra (2007). Additives and crystallization processes: from fundamentals to applications. John Wiley and Sons. p. 212. ISBN 978-0-470-06153-4.
  18. Becker, Wayne M. (1991). The world of the cell. Benjamin/Cummings. ISBN 978-0-8053-0870-9.
  19. Magloire, Kim (2004). Cracking the AP Biology Exam, 2004–2005 Edition. The Princeton Review. p. 45. ISBN 978-0-375-76393-9.
  20. Starr, Cecie (2007-09-25). Biology: Concepts and Applications without Physiology. Cengage Learning. pp. 362, 365. ISBN 978-0495381501.
  21. Hillmer, Gero; Lehmann, Ulrich, translated by J. Lettau (1983). Fossil Invertebrates. CUP Archive. p. 54. ISBN 978-0-521-27028-1.
  22. Knobil, Ernst (1998). Encyclopedia of reproduction, Volume 1. Academic Press. p. 315. ISBN 978-0-12-227020-8.
  23. Schwartz, Jill (2010). Master the GED 2011. Peterson's. p. 371. ISBN 978-0-7689-2885-3.
  24. Hamilton, Matthew B. (2009). Population genetics. Wiley-Blackwell. p. 55. ISBN 978-1-4051-3277-0.
  25. Ville, Claude Alvin; Walker, Warren Franklin; Barnes, Robert D. (1984). General zoology. Saunders College Pub. p. 467. ISBN 978-0-03-062451-3.
  26. Hamilton, William James; Boyd, James Dixon; Mossman, Harland Winfield (1945). Human embryology: (prenatal development of form and function). Williams & Wilkins. p. 330.
  27. Philips, Joy B. (1975). Development of vertebrate anatomy. Mosby. p. 176. ISBN 978-0-8016-3927-2.
  28. The Encyclopedia Americana: a library of universal knowledge, Volume 10. Encyclopedia Americana Corp. 1918. p. 281.
  29. Romoser, William S.; Stoffolano, J. G. (1998). The science of entomology. WCB McGraw-Hill. p. 156. ISBN 978-0-697-22848-2.
  30. Charlesworth, D.; Willis, J.H. (2009). "The genetics of inbreeding depression". Nat. Rev. Genet. 10 (11): 783–796. doi:10.1038/nrg2664. PMID 19834483. 
  31. Bernstein, H.; Hopf, F.A.; Michod, R.E. (1987). The molecular basis of the evolution of sex. Adv. Genet. 24. pp. 323–370. doi:10.1016/s0065-2660(08)60012-7. ISBN 9780120176243. PMID 3324702.
  32. Pusey, Anne; Wolf, Marisa (1996). "Inbreeding avoidance in animals". Trends Ecol. Evol. 11 (5): 201–206. doi:10.1016/0169-5347(96)10028-8. PMID 21237809. 
  33. Petrie, M.; Kempenaers, B. (1998). "Extra-pair paternity in birds: Explaining variation between species and populations". Trends in Ecology and Evolution 13 (2): 52–57. doi:10.1016/s0169-5347(97)01232-9. PMID 21238200. 
  34. Adiyodi, K. G.; Hughes, Roger N.; Adiyodi, Rita G. (July 2002). Reproductive Biology of Invertebrates, Volume 11, Progress in Asexual Reproduction. Wiley. p. 116. ISBN 978-0-471-48968-9.
  35. Schatz, Phil. Concepts of Biology | How Animals Reproduce. OpenStax College. Retrieved 5 March 2018.
  36. Marchetti, Mauro; Rivas, Victoria (2001). Geomorphology and environmental impact assessment. Taylor & Francis. p. 84. ISBN 978-90-5809-344-8.
  37. Levy, Charles K. (1973). Elements of Biology. Appleton-Century-Crofts. p. 108. ISBN 978-0-390-55627-1.
  38. Begon, M.; Townsend, C.; Harper, J. (1996). Ecology: Individuals, populations and communities (Third ed.). Blackwell Science. ISBN 978-0-86542-845-4.
  39. Allen, Larry Glen; Pondella, Daniel J.; Horn, Michael H. (2006). Ecology of marine fishes: California and adjacent waters. University of California Press. p. 428. ISBN 978-0-520-24653-9.
  40. Tim Caro (2005). Antipredator Defenses in Birds and Mammals. University of Chicago Press. pp. 1–6 and passim.
  41. Simpson, Alastair G.B; Roger, Andrew J (2004). "The real 'kingdoms' of eukaryotes". Current Biology 14 (17): R693–6. doi:10.1016/j.cub.2004.08.038. PMID 15341755. 
  42. Stevens, Alison N. P. (2010). "Predation, Herbivory, and Parasitism". Nature Education Knowledge 3 (10): 36. Retrieved 12 February 2018. 
  43. Jervis, M. A.; Kidd, N. A. C (November 1986). "Host-Feeding Strategies in Hymenopteran Parasitoids". Biological Reviews 61 (4): 395–434. doi:10.1111/j.1469-185x.1986.tb00660.x. 
  44. Meylan, Anne (1988-01-22). "Spongivory in Hawksbill Turtles: A Diet of Glass". Science 239 (4838): 393–395. doi:10.1126/science.239.4838.393. PMID 17836872. 
  45. Clutterbuck, Peter (2000). Understanding Science: Upper Primary. Blake Education. p. 9. ISBN 978-1-86509-170-9.
  46. Gupta, P. K. (1900). Genetics Classical To Modern. Rastogi Publications. p. 26. ISBN 978-81-7133-896-2.
  47. Garrett, Reginald; Grisham, Charles M. (2010). Biochemistry. Cengage Learning. p. 535. ISBN 978-0-495-10935-8.
  48. "none". New Scientist 152 (2050–2055): 105. 1996. 
  49. Castro, Peter; Huber, Michael E. (2007). Marine Biology (7th ed.). McGraw-Hill. p. 376. ISBN 978-0-07-722124-9.
  50. Rota-Stabelli, Omar; Daley, Allison C.; Pisani, Davide (2013). "Molecular Timetrees Reveal a Cambrian Colonization of Land and a New Scenario for Ecdysozoan Evolution". Current Biology 23 (5): 392–8. doi:10.1016/j.cub.2013.01.026. PMID 23375891. Retrieved 1 March 2018. 
  51. Daeschler, Edward B.; Shubin, Neil H.; Jenkins, Farish A., Jr. (6 April 2006). "A Devonian tetrapod-like fish and the evolution of the tetrapod body plan". Nature 440 (7085): 757–763. doi:10.1038/nature04639. PMID 16598249. 
  52. Jennifer A. Clack (21 November 2005). "Getting a Leg Up on Land". Scientific American. 
  53. Lynn Margulis, Karlene V. Schwartz, Michael Dolan (1999). Diversity of Life: The Illustrated Guide to the Five Kingdoms. Jones & Bartlett Learning. pp. 115–116. ISBN 978-0-7637-0862-7.CS1 maint: Multiple names: authors list (link)
  54. Clarke, Andrew (2014). "The thermal limits to life on Earth". International Journal of Astrobiology 13 (2): 141–154. doi:10.1017/S1473550413000438. 
  55. Land animals. British Antarctic Survey. Retrieved 7 March 2018.
  56. zoology. San Francisco, California: Wikimedia Foundation, Inc. May 8, 2014. Retrieved 2014-05-18.
  57. mammalogy. San Francisco, California: Wikimedia Foundation, Inc. 16 December 2014. Retrieved 2015-02-23.
  58. ornithology. San Francisco, California: Wikimedia Foundation, Inc. 16 December 2014. Retrieved 2015-02-23.
  59. dinosaurology. San Francisco, California: Wikimedia Foundation, Inc. 4 February 2015. Retrieved 2015-02-23.
  60. herpetology. San Francisco, California: Wikimedia Foundation, Inc. 25 April 2016. Retrieved 2016-05-05.
  61. ophiology. San Francisco, California: Wikimedia Foundation, Inc. 16 December 2014. Retrieved 2015-02-23.
  62. batrachology. San Francisco, California: Wikimedia Foundation, Inc. 16 June 2014. Retrieved 2015-02-23.
  63. Tedius Zanarukando (30 March 2005). ichthyology. San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-02-23.
  64. lepidopterology. San Francisco, California: Wikimedia Foundation, Inc. 7 October 2013. Retrieved 2015-02-23.
  65. Ungoliant MMDCCLXIV (23 December 2017). araneology. San Francisco, California: Wikimedia Foundation, Inc. Retrieved 24 September 2018.
  66. Ronald L. Shimek (January 2006). Nano-Animals, Part I: Rotifers. Retrieved 2016-01-21.
  67. "Eukaryota, In: Wikispecies". San Francisco, California: Wikimedia Foundation, Inc. 13 November 2015. Retrieved 2016-01-21.

External links[edit]