tail
{{Short description|Distinct, flexible appendage to the torso of an animal}}
File:White-tailed deer, tail up.jpg's tail]]
The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolved to lose their tails (e.g. frogs and hominid primates), the coccyx is the homologous vestigial of the tail. While tails are primarily considered a feature of vertebrates, some invertebrates such as scorpions and springtails, as well as snails and slugs, have tail-like appendages that are also referred to as tails.
Tail-shaped objects are sometimes referred to as "caudate" (e.g. caudate lobe, caudate nucleus), and the body part associated with or proximal to the tail are given the adjective "caudal" (which is considered a more precise anatomical terminology).
Function
File:Alopex lagopus IMG 9019.JPG (Arctic fox) sleeping with its tail wrapped as a blanket.]]
Animal tails are used in a variety of ways. They provide a source of thrust for aquatic locomotion for fish, cetaceans and crocodilians and other forms of marine life.{{cite book|author=Robert W. Blake|title=Fish Locomotion |url=https://books.google.com/books?id=M7E8AAAAIAAJ&pg=PA143|date=26 May 1983|publisher=CUP Archive |isbn=978-0-521-24303-2|page=143}} Terrestrial species of vertebrates that do not need to swim, e.g. cats and kangaroos, instead use their tails for balance;{{Cite journal |last1=Lacava |first1=Salvatore A. |last2=Isilak |first2=Necmettin |last3=Uusisaari |first3=Marylka Y. |date=2024-11-06 |title=The role of mouse tails in response to external and self-generated balance perturbations on the roll plane |journal=Journal of Experimental Biology |volume=227 |issue=21 |pages=jeb247552 |doi=10.1242/jeb.247552 |issn=0022-0949 |pmc=11574348 |pmid=39318334|bibcode=2024JExpB.227B7552L }}{{cite book|title=Outwitting Cats: Tips, Tricks and Techniques for Persuading the Felines in Your Life That What You Want Is Also What They Want| date=2004 |url=https://books.google.com/books?id=WmuQQXU6EtAC&pg=PA21|publisher=Rowman & Littlefield|isbn=978-1-59921-625-6|page=21}}{{cite book |author=Byron Dawson|title=The Heinemann Science Scheme|url=https://books.google.com/books?id=SDm82kL--uoC&pg=PT125 |year=2003 |publisher=Heinemann |isbn=978-0-435-58332-3|page=125}} and some, such as monkeys and opossums, have grasping prehensile tails, which are adapted for arboreal locomotion.{{cite book|author=Melissa Stewart|title=New World Monkeys|url=https://books.google.com/books?id=iUnDmeI3B1IC&pg=PA11 |date=1 January 2007|publisher=Lerner Publications|isbn=978-0-8225-6765-3|page=11}}
Many animals use their tail for utility purposes, for example many grazing animals, such as horses and oxen, use their tails to drive away parasitic flies and sweep off other biting insects.{{cite book|author1=Gilbert WALDBAUER|author2=Gilbert Waldbauer|title=What Good Are Bugs? Insects in the Web of Life|url=https://books.google.com/books?id=Vis8XubJ_-QC&pg=PA253|date=30 June 2009|publisher=Harvard University Press|isbn=978-0-674-04474-6|page=253}}{{cite book|author1=Mary Pope Osborne|author2=Natalie Pope Boyce|title=Magic Tree House Fact & Fiction: Horses|url=https://books.google.com/books?id=6pBoBAAAQBAJ&pg=PT113|date=28 October 2014|publisher=Random House Children's Books|isbn=978-0-553-52368-3|page=113}} Some animals with broad, furry tails (e.g. foxes) often wrap the tail around the body as means of thermal insulation like a blanket.
Some species' tails serve aggressive functions, either predatorily or defensively. For example, the tails of scorpions have a stinger that contain venom, which can be used to either kill large prey or to fight off a threat.{{cite book|author=Adele Richardson|title=Scorpions|url=https://books.google.com/books?id=RcEkzllZzVEC&pg=PA20|date=1 July 2002|publisher=Capstone|isbn=978-0-7368-1318-1|page=20}} Similarly, stingrays have a thickened spine that can deliver penetrating trauma. Thresher sharks are known to use their long tails to stun prey. Many species of snakes wiggle their tails as a lure to attract prey, who may mistake the tail as a worm. The extinct armored dinosaurs (stegosaurs and ankylosaurs) have tails with spikes or clubs as defensive weapons against predators.
Tails are also used for communication and signalling. Most canines use their tails to communicate mood and intention.{{cite journal|author1=Masashi Hasegawa|author2=Nobuyo Ohtani|title=Dogs' Body Language Relevant to Learning Achievement|journal=Animals |date=February 2014|volume=4 |issue=1 |pages=45–58 |publisher=Azabu University School of Veterinary Medicine|pmid=26479883|pmc=4494300|doi=10.3390/ani4010045|doi-access=free }} Some deer species flash the white underside of their tails to warn other nearby deer of possible danger,{{cite book|author=D. Muller-Schwarze|title=Chemical Signals: Vertebrates and Aquatic Invertebrates|url=https://books.google.com/books?id=WHzVBwAAQBAJ&pg=PA47 |date=6 December 2012|publisher=Springer Science & Business Media|isbn=978-1-4684-1027-3|page=47}} beavers slap the water with their tails to indicate danger,{{cite book|author=Bruce M. Carlson|title=Beneath the Surface: A Natural History of a Fisherman's Lake|url=https://books.google.com/books?id=omHZolGetNoC&pg=PT240|date=14 October 2008|publisher=Minnesota Historical Society|isbn=978-0-87351-656-3|page=240}} felids raise and quiver their tails while scent-marking,{{Cite book |last1=Sunquist |first1=Mel |url=https://books.google.com/books?id=IF8nDwAAQBAJ&pg=PA414 |title=Wild Cats of the World |last2=Sunquist |first2=Fiona |date=2017-05-15 |publisher=University of Chicago Press |isbn=978-0-226-51823-7 |language=en}} and canids (including domestic dogs) indicate emotions through the positioning and movement of their tails.{{cite book|author1=Stanley Coren|author2=Sarah Hodgson|title=Understanding Your Dog For Dummies|url=https://books.google.com/books?id=nzAsR5VPXkgC&pg=PA250|date=15 February 2011|publisher=John Wiley & Sons|isbn=978-1-118-05276-1|page=250}} Rattlesnakes perform tail vibration to generate a distinct rattling noise that signals aggression and warns potential predators to stay away.
Some species of lizard (e.g. geckos) can self-amputate ("cast") their tails from their bodies to help them escape predators, which are either distracted by the wriggling detached tail or only manages to seize the severed tail while the lizard flees. Tails cast in this manner generally grow back over time, though the replacement is typically darker in colour than the original and contains only cartilage, not bone.{{cite book|author1=Stephen J. Divers|author2=Douglas R. Mader|title=Reptile Medicine and Surgery|url=https://books.google.com/books?id=7Ai4BKhi0VUC&pg=PT3468|date=13 December 2005|publisher=Elsevier Health Sciences|isbn=1-4160-6477-X|page=3468}} Various species of rat demonstrate a similar function with their tails, known as degloving, in which the outer layer is shed in order for the animal to escape from a predator.{{Cite journal|last=Mackenzie|first=SJ|date=2015|title=Innervation and function of rat tail muscles for modeling cauda equina injury and repair|journal=Muscle and Nerve|volume=52|issue=1|pages=94–102|doi=10.1002/mus.24498|pmid=25346299|s2cid=40356618 }}
Most birds' tails end in long feathers called rectrices. These feathers are used as a rudder, helping the bird steer and maneuver in flight; they also help the bird to balance while it is perched.{{cite book|author=David Burnie|title=DK Eyewitness Books: Bird|url=https://books.google.com/books?id=ibgDU5eDVu4C&pg=PA19|date=5 May 2008|publisher=DK Publishing|isbn=978-0-7566-6758-0|page=19}} In some species—such as birds of paradise, lyrebirds, and most notably peafowl—modified tail feathers play an important role in courtship displays.{{cite book|title=Exploring Life Science|url=https://archive.org/details/exploringlifesci10mars|url-access=registration|year=2000|publisher=Marshall Cavendish|isbn=978-0-7614-7145-5|page=[https://archive.org/details/exploringlifesci10mars/page/731 731]}} The extra-stiff tail feathers of other species, including woodpeckers and woodcreepers, allow them to brace themselves firmly against tree trunks.{{cite book|author=Robert W. McFarlane|title=A Stillness in the Pines: The Ecology of the Red-cockaded Woodpecker|url=https://books.google.com/books?id=fBVPQqWpFCkC&pg=PA40|year=1994|publisher=Norton|isbn=978-0-393-31167-9|page=40}}
Human tails
In humans, tail bud refers to the part of the embryo which develops into the end of the spine.{{cite web |url=https://www.merriam-webster.com/medical/tail%20bud | title=Tail Bud |publisher=Merriam Webster |access-date=4 June 2020}}
Infrequently, a child is born with a "soft tail", which contains no vertebrae, but only blood vessels, muscles, and nerves, but this is regarded as an abnormality rather than a vestigial true tail, even when such an appendage is located where the tail would be expected.{{cite news | title=Human tail–caudal appendage: tethered cord |date= February 1, 2008| url = http://www.nature.com/jp/journal/v28/n7/full/jp200839a.html | work = Nature | access-date = 2009-04-28 }}{{cite news | title= The 'human tail' causing tethered cervical cord |date= November 14, 2006 | url= http://www.nature.com/sc/journal/v45/n8/full/3101988a.html | work = Nature | access-date = 2009-04-28}} Fewer than 40 cases have been reported of infants with "true tails" containing the caudal vertebrae, a result of atavism.{{cite journal |last1= Shad |first1= Jimmy |last2= Biswas |first2= Rakesh |date= April 18, 2012 |title= An infant with caudal appendage |journal= BMJ Case Reports |volume= 2012 |pages= bcr1120115160 | doi= 10.1136/bcr.11.2011.5160 | pmid= 22604513 |pmc= 3339178 }}
In 2024, scientists claimed to have found a genetic mutation that contributed to the loss of the tail in the common ancestor of humans and other apes.{{cite news |last=Weisberger |first=Mindy |title=Why don't humans have tails? Scientists find answers in an unlikely place |url=https://www.cnn.com/2024/03/23/world/humans-tails-genetic-mutation-junk-dna-scn/index.html |date=March 23, 2024 |work=CNN |url-status=live |archiveurl=https://archive.today/20240324031927/https://www.cnn.com/2024/03/23/world/humans-tails-genetic-mutation-junk-dna-scn/index.html |archivedate=March 24, 2024 |accessdate=March 24, 2024 }}{{Cite journal |last=Callaway |first=Ewen |date=2024-02-28 |title=How humans lost their tails — and why the discovery took 2.5 years to publish |url=https://www.nature.com/articles/d41586-024-00610-x |journal=Nature |volume=627 |issue=8002 |pages=15–16 |language=en |doi=10.1038/d41586-024-00610-x|pmid=38418734 |bibcode=2024Natur.627...15C |url-access=subscription }}
Humans have a "tailbone" (the coccyx) attached to the pelvis; it comprises fused vertebrae, usually four, at the bottom of the vertebral column. It does not normally protrude externally - humans are an acaudal (or acaudate) species (i.e., tailless).
Gallery
File:Cub Stalks Tail.jpg|Lion (Panthera leo)
File:Scorpion tail.jpg|Scorpion
File:Pig tail DSC03974.jpg|Pig (Sus domestica)
File:Queue glyptodon museum dijo.jpg|Glyptodon (Glyptodon asper)
File:Lactoria cornuta (cola).006 - Aquarium Finisterrae.JPG|Longhorn cowfish (Lactoria cornuta)
File:La Palmyre 041-crop.jpg|Grévy's zebra (Equus grevyi)
File:Alligator Tail.jpg|American alligator (Alligator mississipiensis)
File:Flusspferd Backstage.JPG|Hippopotamus (Hippopotamus amphibius)
File:Red Wolf butt.jpg|Red wolf (Canis rufus)
See also
- Empennage, the tail of an aircraft
- Rump (animal)
References
{{reflist|30em}}