Volvation (from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''volvere'' "roll", and the suffix ''-(a)tion''; sometimes called enrolment or conglobation), is a defensive behavior in certain

animals Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a ...

, in which the animal rolls its own body into a ball, presenting only the hardest parts of its

integument In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, Exoskeleton, shell, germ or Peel (fruit), rind. Etymology The term is derived from ''integumentum'', which is Latin for "a coverin ...

(the animal's "armor"), or its spines to

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

. Among mammals, vertebrates like

pangolin Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (). The one extant family, the Manidae, has three genera: '' Manis'', '' Phataginus'', and '' Smutsia''. ''Manis'' comprises four species found in Asia, while ' ...

s (

Manidae Manidae (" spirits") is the only extant family of pangolins. This family comprises three genera ('' Manis'' from subfamily Maninae, '' Phataginus'' from subfamily Phatagininae, and '' Smutsia'' from subfamily Smutsiinae), as well as the extinct ...

) and

hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are 17 species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introduction. The ...

s (

Erinaceidae Erinaceidae is a family in the order Eulipotyphla, consisting of the hedgehogs and moonrats. Until recently, it was assigned to the order Erinaceomorpha, which has been subsumed with the paraphyletic Soricomorpha into Eulipotyphla. Eulipotyphl ...

) exhibit the ability to conglobate.

Armadillo Armadillos () are New World placental mammals in the order (biology), order Cingulata. They form part of the superorder Xenarthra, along with the anteaters and sloths. 21 extant species of armadillo have been described, some of which are dis ...

s in the genus

Tolypeutes The genus ''Tolypeutes'' contains the two species of three-banded armadillos. They are restricted to open and semi-open habitats in South America. Of the several armadillo genera, only ''Tolypeutes'' rely heavily on their armor for protection. W ...

(South American three-banded armadillos) are able to roll into a defensive ball; however the

nine-banded armadillo The nine-banded armadillo (''Dasypus novemcinctus''), also called the nine-banded long-nosed armadillo or common long-nosed armadillo, is a species of armadillo native to North America, North, Central America, Central, and South America, making ...

and other species have too many plates..

Earthworms An earthworm is a soil-dwelling terrestrial animal, terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (biology), class (or subclass (biology), subclass, depending on ...

may volvate during periods of extreme heat or

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

. Among

pill millipede Pill millipedes are any members of two living (and one extinct) orders of millipedes, often grouped together into a single superorder, Oniscomorpha. The name Oniscomorpha refers to the millipedes' resemblance to certain woodlice (Oniscidea), also ...

s, volvation is both a protection against external threats and against

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

. At least eight families of flat-backed millipedes are known to practice true volvation, they are referred to as ''oniscoid'' (

woodlouse Woodlice are terrestrial isopods in the suborder Oniscidea. Their name is derived from being often found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects. Woodlice evolved from marine isopods ...

-like). The

pauropod Pauropoda is a class of small, pale, millipede-like arthropods in the subphylum Myriapoda. More than 900 species in twelve families are found worldwide, living in soil and leaf mold. Pauropods look like centipedes or millipedes and may be a sist ...

family Sphaeropauropodidae has the ability to coil completely into a tight sphere, as it's name suggests. Woodlice or pillbugs (

Armadillidae Armadillidae is a family of woodlouse, woodlice (Oniscidea; terrestrial crustaceans), comprising around 80 genera and 700 species. It is the largest family of Oniscidea, and one of the most species-rich families of the entire Isopoda. Most of ...

) curl themselves into "pills" not only for defense, but also to conserve moisture while resting or sleeping, because they must keep their pseudotrachaea ("gills") wet. Volvation is particularly well evolved in subterranean isopods, but only '' Caecosphaeroma burgundum'' is able to roll up into a hermetic sphere without any outward projections, and thus "approaches perfection in volvation". Multi-shelled chitons also volvate, although evidence suggests that they do not use this behavior as an anti-predatory defense but rather as a form of locomotion. In vertebrates, an animal's decision to volvate is mediated by the

periaqueductal gray The periaqueductal gray (PAG), also known as the central gray, is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for ...

region.

Gallery

File:Erinaceus-europaeus 2.jpg, The

European hedgehog The European hedgehog (''Erinaceus europaeus''), also known as the West European hedgehog or common hedgehog, is a hedgehog species native to Europe from Iberia and Italy northwards into Scandinavia and westwards into the British Isles.Harris, S. ...

(''Erinaceus europaeus''). File:Tatou en boule.JPG, The Southern three-banded armadillo (''Tolypeutes matacus''). File:Pangolin defending itself from lions (Gir Forest, Gujarat, India).jpg, An

Indian pangolin The Indian pangolin (''Manis crassicaudata''), also called thick-tailed pangolin and scaly anteater, is a pangolin native to the Indian subcontinent. Like other pangolins, it has large, overlapping Scale (zoology), scales on its body which act as ...

(''Manis crassicaudata'') defending itself against Asiatic lions (''Panthera leo leo''). File:Lesser Hedgehog-tenrecs (Echinops telfairi) (10292363783).jpg, Two lesser hedgehog tenrecs (''Echinops telfairi''). File:Echidna, Exmouth.jpg,

Short-beaked echidna The short-beaked echidna (''Tachyglossus aculeatus''), also called the short-nosed echidna, is one of four living species of echidna, and the only member of the genus ''Tachyglossus'', from Ancient Greek (), meaning "fast", and (), meaning ...

(''Tachyglossus aculeatus'') curling into a ball. BallPythonWithClutch.jpg, The ball python (''Python regius'') curls into a ball when stressed or frightened. Ouroborus cataphractus02.jpg, The armadillo girdled lizard (''Ouroborus cataphractus''). Armadillidium vulgare 000.jpg, The common pillbug (''Armadillidium vulgare'') is named after the pill it resembles when curled up. Phacops-enrolled.jpg, '' Phacops rana'', a

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

from the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

period. Tachypodoiulus niger 2.jpg, ''

Tachypodoiulus niger ''Tachypodoiulus niger'', known variously as the white-legged snake millipede or the black millipede, is a European species of millipede. It is very similar to other species such as '' Cylindroiulus londinensis'', from which it can be reliably d ...

'', a

millipede Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derive ...

, with legs on the inside and head in the center. Glomeris marginata Pill Millipede Unrolling.jpg, Stages of a

(''Glomeris marginata'') unrolling.

References

{{reflist Ethology Predation Antipredator adaptations

Gallery

See also

References