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Meylan, Anne (22 January 1988). "Spongivory in Hawksbill Turtles: A Diet of Glass". Science. 239 (4838): 393–395. Bibcode: 1988Sci...239..393M. doi: 10.1126/science.239.4838.393. JSTOR 1700236. PMID 17836872. S2CID 22971831. Having a front end means that this part of the body encounters stimuli, such as food, favouring cephalisation, the development of a head with sense organs and a mouth. Many bilaterians have a combination of circular muscles that constrict the body, making it longer, and an opposing set of longitudinal muscles, that shorten the body; [136] these enable soft-bodied animals with a hydrostatic skeleton to move by peristalsis. [137] They also have a gut that extends through the basically cylindrical body from mouth to anus. Many bilaterian phyla have primary larvae which swim with cilia and have an apical organ containing sensory cells. However, over evolutionary time, descendant spaces have evolved which have lost one or more of each of these characteristics. For example, adult echinoderms are radially symmetric (unlike their larvae), while some parasitic worms have extremely simplified body structures. [135] [136] Giribet and Edgecombe (2020) provide what they consider to be a consensus internal phylogeny of the animals, embodying uncertainty about the structure at the base of the tree (dashed lines). [121] Animalia Crouse, Richard (2008). Son of the 100 Best Movies You've Never Seen. ECW Press. p.200. ISBN 978-1-55490-330-6. Being such an inhospitable place, Antarctica is low in biodiversity. Very little life exists in the continent’s frozen interior. Most Antarctic species are found on the coast, particularly on the Antarctic Peninsula; the northernmost part of Antarctica.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. Ville, Claude Alvin; Walker, Warren Franklin; Barnes, Robert D. (1984). General zoology. Saunders College Pub. p.467. ISBN 978-0-03-062451-3.

Sangwal, Keshra (2007). Additives and crystallization processes: from fundamentals to applications. John Wiley and Sons. p. 212. ISBN 978-0-470-06153-4. People have used hunting dogs to help chase down and retrieve animals, [193] and birds of prey to catch birds and mammals, [194] while tethered cormorants have been used to catch fish. [195] Poison dart frogs have been used to poison the tips of blowpipe darts. [196] [197] 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. PMC 1693093. PMID 12594915. Europe is the world’s second-smallest continent, being smaller than Antarctica and larger than Australia. Find sources: "Lists of animals"– news · newspapers · books · scholar · JSTOR ( August 2022) ( Learn how and when to remove this template message)Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and multicellular. [12] Unlike plants and algae, which produce their own nutrients, [13] animals are heterotrophic, [14] [15] feeding on organic material and digesting it internally. [16] With very few exceptions, animals respire aerobically. [a] [18] All animals are motile [19] (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 embryonic development that is unique to animals, allowing cells to be differentiated into specialised tissues and organs. [20] Structure History of Falconry". The Falconry Centre. Archived from the original on 29 May 2016 . Retrieved 22 April 2016. Seilacher, Adolf (2007). Trace fossil analysis. Berlin: Springer. pp.176–177. ISBN 978-3-540-47226-1. OCLC 191467085. a b c d Nicol, David (June 1969). "The Number of Living Species of Molluscs". Systematic Zoology. 18 (2): 251–254. doi: 10.2307/2412618. JSTOR 2412618. a b c d e f g h i j k l m n o Zhang, Zhi-Qiang (30 August 2013). "Animal biodiversity: An update of classification and diversity in 2013. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013)". Zootaxa. 3703 (1): 5. doi: 10.11646/zootaxa.3703.1.3. Archived from the original on 24 April 2019 . Retrieved 2 March 2018.