Tail

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A white-tailed deer's tail White-tailed deer, tail up.jpg
A white-tailed deer'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.

Contents

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

Vulpes lagopus (Arctic fox) sleeping with its tail wrapped as a blanket. Alopex lagopus IMG 9019.JPG
Vulpes lagopus (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. [1] Terrestrial species of vertebrates that do not need to swim, e.g. cats and kangaroos, instead use their tails for balance; [2] [3] and some, such as monkeys and opossums, have grasping prehensile tails, which are adapted for arboreal locomotion. [4]

Many animals use their tail for utility purposes, for example many grazing animals, such as horses and oxens, use their tails to drive away parasitic flies and sweep off other biting insects. [5] [6] 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. [7] 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. [8] Some deer species flash the white underside of their tails to warn other nearby deer of possible danger, [9] beavers slap the water with their tails to indicate danger, [10] felids raise and quiver their tails while scent-marking, [11] and canids (including domestic dogs) indicate emotions through the positioning and movement of their tails. [12] 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. [13] 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. [14]

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. [15] In some species—such as birds of paradise, lyrebirds, and most notably peafowl —modified tail feathers play an important role in courtship displays. [16] The extra-stiff tail feathers of other species, including woodpeckers and woodcreepers, allow them to brace themselves firmly against tree trunks. [17]

Human tails

Tail-like structure on a female newborn from coccyx protrusion Gould Pyle 129.jpg
Tail-like structure on a female newborn from coccyx protrusion

In humans, tail bud refers to the part of the embryo which develops into the end of the spine. [18] However, this is not a tail. [19] 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. [20] [21] Fewer than 40 cases have been reported of infants with "true tails" containing the caudal vertebrae, a result of atavism. [22]

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. [23] [24]

Humans have a "tail bone" (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).

See also

Related Research Articles

<span class="mw-page-title-main">Anatomy</span> Study of the structure of organisms

Anatomy is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology, which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine, and is often studied alongside physiology.

<span class="mw-page-title-main">Fin</span> Thin component or appendage attached to a larger body or structure

A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.

<span class="mw-page-title-main">Skeleton</span> Part of the body that forms the supporting structure

A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal frame to which the organs and soft tissues attach; and the hydroskeleton, a flexible internal structure supported by the hydrostatic pressure of body fluids.

<span class="mw-page-title-main">Snake</span> Limbless, scaly, elongate reptile

Snakes are elongated, limbless reptiles of the suborder Serpentes. Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads. To accommodate their narrow bodies, snakes' paired organs appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have independently evolved elongate bodies without limbs or with greatly reduced limbs at least twenty-five times via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal.

<span class="mw-page-title-main">Coccyx</span> Bone of the pelvis

The coccyx, commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates since Nacholapithecus, the coccyx is the remnant of a vestigial tail. In animals with bony tails, it is known as tailhead or dock, in bird anatomy as tailfan. It comprises three to five separate or fused coccygeal vertebrae below the sacrum, attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between the sacrum and the coccyx.

<span class="mw-page-title-main">Prehensile tail</span> Tail of an animal that has adapted to be able to grasp or hold objects

A prehensile tail is the tail of an animal that has adapted to grasp or hold objects. Fully prehensile tails can be used to hold and manipulate objects, and in particular to aid arboreal creatures in finding and eating food in the trees. If the tail cannot be used for this it is considered only partially prehensile; such tails are often used to anchor an animal's body to dangle from a branch, or as an aid for climbing. The term prehensile means "able to grasp".

<span class="mw-page-title-main">Somite</span> Each of several blocks of mesoderm that flank the neural tube on either side in embryogenesis

The somites are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide into the dermatomes, myotomes, sclerotomes and syndetomes that give rise to the vertebrae of the vertebral column, rib cage, part of the occipital bone, skeletal muscle, cartilage, tendons, and skin.

<span class="mw-page-title-main">Animal locomotion</span> Self-propulsion by an animal

In ethology, animal locomotion is any of a variety of methods that animals use to move from one place to another. Some modes of locomotion are (initially) self-propelled, e.g., running, swimming, jumping, flying, hopping, soaring and gliding. There are also many animal species that depend on their environment for transportation, a type of mobility called passive locomotion, e.g., sailing, kiting (spiders), rolling or riding other animals (phoresis).

<span class="mw-page-title-main">Autotomy</span> Self-amputation

Autotomy or 'self-amputation', is the behaviour whereby an animal sheds or discards an appendage, usually as a self-defense mechanism to elude a predator's grasp or to distract the predator and thereby allow escape. Some animals are able to regenerate the lost body part later. Autotomy is thought to have evolved independently at least nine times. The term was coined in 1883 by Leon Fredericq.

<span class="mw-page-title-main">Pygostyle</span> Skeletal condition involving fusion of caudal vertebrae into a single ossification

Pygostyle describes a skeletal condition in which the final few caudal vertebrae are fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these. The pygostyle is the main component of the uropygium, a structure colloquially known as the bishop's nose, parson's nose, pope's nose, or sultan's nose. This is the fleshy protuberance visible at the posterior end of a bird that has been dressed for cooking. It has a swollen appearance because it also contains the uropygial gland that produces preen oil.

<i>Massospondylus</i> Sauropodomorph dinosaur genus from Early Jurassic South Africa and Botswana

Massospondylus was a genus of sauropodomorph dinosaur from the Early Jurassic. It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found at other locations in South Africa, Lesotho, and Zimbabwe. Material from Arizona's Kayenta Formation, India, and Argentina has been assigned to the genus at various times, but the Arizonan and Argentinian material are now assigned to other genera.

<span class="mw-page-title-main">Terrestrial locomotion</span> Ability of animals to travel on land

Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that in water, with reduced friction being replaced by the increased effects of gravity.

Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capable of very high metabolic rates and oxygen supply, permit the bird to fly. The development of a beak has led to evolution of a specially adapted digestive system.

A limb is a jointed, muscled appendage of a tetrapod vertebrate animal used for weight-bearing, terrestrial locomotion and physical interaction with other objects. The distalmost portion of a limb is known as its extremity. The limbs' bony endoskeleton, known as the appendicular skeleton, is homologous among all tetrapods, who use their limbs for walking, running and jumping, swimming, climbing, grasping, touching and striking.

<i>Glyptodon</i> Genus of large, heavily armored mammals

Glyptodon is a genus of glyptodont, an extinct group of large, herbivorous armadillos, that lived from the Pliocene, around 3.2 million years ago, to the early Holocene, around 11,000 years ago, in South America. It is one of, if not the, best known genus of glyptodont. Glyptodon has a long and storied past, being the first named extinct cingulate and the type genus of the subfamily Glyptodontinae. Fossils of Glyptodon have been recorded as early as 1814 from Pleistocene aged deposits from Uruguay, though many were incorrectly referred to the ground sloth Megatherium by early paleontologists.

<span class="mw-page-title-main">Aquatic locomotion</span> Biologically propelled motion through a liquid medium

Aquatic locomotion or swimming is biologically propelled motion through a liquid medium. The simplest propulsive systems are composed of cilia and flagella. Swimming has evolved a number of times in a range of organisms including arthropods, fish, molluscs, amphibians, reptiles, birds, and mammals.

<span class="mw-page-title-main">Vertebral column</span> Bony structure found in vertebrates

The vertebral column, also known as the spinal column, spine or backbone, is the core part of the axial skeleton in vertebrate animals. The vertebral column is the defining and eponymous characteristic of the vertebrate endoskeleton, where the notochord found in all chordates has been replaced by a segmented series of mineralized irregular bones called vertebrae, separated by fibrocartilaginous intervertebral discs. The dorsal portion of the vertebral column houses the spinal canal, an elongated cavity formed by alignment of the vertebral neural arches that encloses and protects the spinal cord, with spinal nerves exiting via the intervertebral foramina to innervate each body segments.

<span class="mw-page-title-main">Fish fin</span> Bony skin-covered spines or rays protruding from the body of a fish

Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only by muscles.

<span class="mw-page-title-main">Deimatic behaviour</span> Bluffing display of an animal used to startle or scare a predator

Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey animal an opportunity to escape. The term deimatic or dymantic originates from the Greek δειματόω (deimatóo), meaning "to frighten".

<span class="mw-page-title-main">Vertebra</span> Bone in the vertebral column

Each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal segment and the particular species.

References

  1. ↑ Robert W. Blake (26 May 1983). Fish Locomotion. CUP Archive. p. 143. ISBN   978-0-521-24303-2.
  2. ↑ Outwitting Cats: Tips, Tricks and Techniques for Persuading the Felines in Your Life That What You Want Is Also What They Want. Rowman & Littlefield. 2004. p. 21. ISBN   978-1-59921-625-6.
  3. ↑ Byron Dawson (2003). The Heinemann Science Scheme. Heinemann. p. 125. ISBN   978-0-435-58332-3.
  4. ↑ Melissa Stewart (1 January 2007). New World Monkeys. Lerner Publications. p. 11. ISBN   978-0-8225-6765-3.
  5. ↑ Gilbert WALDBAUER; Gilbert Waldbauer (30 June 2009). What Good Are Bugs? Insects in the Web of Life. Harvard University Press. p. 253. ISBN   978-0-674-04474-6.
  6. ↑ Mary Pope Osborne; Natalie Pope Boyce (28 October 2014). Magic Tree House Fact & Fiction: Horses. Random House Children's Books. p. 113. ISBN   978-0-553-52368-3.
  7. ↑ Adele Richardson (1 July 2002). Scorpions. Capstone. p. 20. ISBN   978-0-7368-1318-1.
  8. ↑ Masashi Hasegawa; Nobuyo Ohtani (February 2014). "Dogs' Body Language Relevant to Learning Achievement". Animals. 4 (1). Azabu University School of Veterinary Medicine: 45–58. doi: 10.3390/ani4010045 . PMC   4494300 . PMID   26479883.
  9. ↑ D. Muller-Schwarze (6 December 2012). Chemical Signals: Vertebrates and Aquatic Invertebrates. Springer Science & Business Media. p. 47. ISBN   978-1-4684-1027-3.
  10. ↑ Bruce M. Carlson (14 October 2008). Beneath the Surface: A Natural History of a Fisherman's Lake. Minnesota Historical Society. p. 240. ISBN   978-0-87351-656-3.
  11. ↑ Sunquist, Mel; Sunquist, Fiona (2017-05-15). Wild Cats of the World. University of Chicago Press. ISBN   978-0-226-51823-7.
  12. ↑ Stanley Coren; Sarah Hodgson (15 February 2011). Understanding Your Dog For Dummies. John Wiley & Sons. p. 250. ISBN   978-1-118-05276-1.
  13. ↑ Stephen J. Divers; Douglas R. Mader (13 December 2005). Reptile Medicine and Surgery. Elsevier Health Sciences. p. 3468. ISBN   1-4160-6477-X.
  14. ↑ Mackenzie, SJ (2015). "Innervation and function of rat tail muscles for modeling cauda equina injury and repair". Muscle and Nerve. 52 (1): 94–102. doi:10.1002/mus.24498. PMID   25346299. S2CID   40356618.
  15. ↑ David Burnie (5 May 2008). DK Eyewitness Books: Bird. DK Publishing. p. 19. ISBN   978-0-7566-6758-0.
  16. ↑ Exploring Life Science . Marshall Cavendish. 2000. p.  731. ISBN   978-0-7614-7145-5.
  17. ↑ Robert W. McFarlane (1994). A Stillness in the Pines: The Ecology of the Red-cockaded Woodpecker. Norton. p. 40. ISBN   978-0-393-31167-9.
  18. ↑ "Tail Bud". Merriam Webster. Retrieved 4 June 2020.
  19. ↑ "Developmental Stages in Human Embryos: Stage 16". the Endowment for Human Development. Retrieved 4 June 2020. What Kunitomo (1918) designated the "longest tail" at stage 16 is nothing of the kind but is merely the caudal end of the embryo, which will develop into the coccygeal region.
  20. ↑ "Human tail–caudal appendage: tethered cord". Nature . February 1, 2008. Retrieved 2009-04-28.
  21. ↑ "The 'human tail' causing tethered cervical cord". Nature . November 14, 2006. Retrieved 2009-04-28.
  22. ↑ Shad, Jimmy; Biswas, Rakesh (April 18, 2012). "An infant with caudal appendage". BMJ Case Reports. 2012: bcr1120115160. doi:10.1136/bcr.11.2011.5160. PMC   3339178 . PMID   22604513.
  23. ↑ Weisberger, Mindy (March 23, 2024). "Why don't humans have tails? Scientists find answers in an unlikely place". CNN . Archived from the original on March 24, 2024. Retrieved March 24, 2024.
  24. ↑ Callaway, Ewen (2024-02-28). "How humans lost their tails — and why the discovery took 2.5 years to publish". Nature. 627 (8002): 15–16. Bibcode:2024Natur.627...15C. doi:10.1038/d41586-024-00610-x. PMID   38418734.
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