Further information: Largest organisms and Smallest organisms The blue whale is the largest animal that has ever lived. Main articles: Protostome and Deuterostome The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus. Giribet, G.; Distel, D.L.; Polz, M.; Sterrer, W.; Wheeler, W.C. (2000). "Triploblastic relationships with emphasis on the acoelomates and the position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: a combined approach of 18S rDNA sequences and morphology". Syst Biol. 49 (3): 539–562. doi: 10.1080/10635159950127385. PMID 12116426.

Animals from both groups possess a complete digestive tract, but in protostomes the first opening of the embryonic gut develops into the mouth, and the anus forms secondarily. In deuterostomes, the anus forms first while the mouth develops secondarily. [143] [144] Most protostomes have schizocoelous development, where cells simply fill in the interior of the gastrula to form the mesoderm. In deuterostomes, the mesoderm forms by enterocoelic pouching, through invagination of the endoderm. [145] Being such a large region, Asia contains a wide range of habitats (and a correspondingly wide range of animals).

Uetz, P. "A Quarter Century of Reptile and Amphibian Databases". Herpetological Review. 52: 246–255. Archived from the original on 21 February 2022 . Retrieved 2 October 2021– via ResearchGate.

EU statistics show decline in animal research numbers". Speaking of Research. 2013. Archived from the original on 6 October 2017 . Retrieved 24 January 2016. Tester, S. Jim (1987). A History of Western Astrology. Boydell & Brewer. pp.31–33 and passim. ISBN 978-0-85115-446-6.

Hummel, Richard (1994). Hunting and Fishing for Sport: Commerce, Controversy, Popular Culture. Popular Press. ISBN 978-0-87972-646-1. Mazzetta, Gerardo V.; Christiansen, Per; Fariña, Richard A. (2004). "Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs". Historical Biology. 16 (2–4): 71–83. CiteSeerX 10.1.1.694.1650. doi: 10.1080/08912960410001715132. S2CID 56028251.

Lau, Theodora (2005). The Handbook of Chinese Horoscopes. Souvenir Press. pp.2–8, 30–35, 60–64, 88–94, 118–124, 148–153, 178–184, 208–213, 238–244, 270–278, 306–312, 338–344. The following table lists estimated numbers of described extant species for the major animal phyla, [66] along with their principal habitats (terrestrial, fresh water, [67] and marine), [68] and free-living or parasitic ways of life. [69] Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million. [70] Using patterns within the taxonomic hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011. [71] [72] [b] Phylum Castro, Peter; Huber, Michael E. (2007). Marine Biology (7thed.). McGraw-Hill. p.376. ISBN 978-0-07-722124-9. Animals are monophyletic, meaning they are derived from a common ancestor. Animals are sister to the Choanoflagellata, with which they form the Choanozoa. [106]A wide variety of terrestrial and aquatic animals are hunted for sport. [205] Symbolic uses Artistic vision: Still Life with Lobster and Oysters by Alexander Coosemans, c. 1660 Mentel, Marek; Martin, William (2010). "Anaerobic animals from an ancient, anoxic ecological niche". BMC Biology. 8: 32. doi: 10.1186/1741-7007-8-32. PMC 2859860. PMID 20370917. Main article: Ecdysozoa Ecdysis: a dragonfly has emerged from its dry exuviae and is expanding its wings. Like other arthropods, its body is divided into segments. a b Valentine, James W. (2004). On the Origin of Phyla. University of Chicago Press. pp.7–8. ISBN 978-0-226-84548-7.