Autohaemorrhaging, or reflex bleeding, is the action of animals deliberately ejecting

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...

from their bodies. Autohaemorrhaging has been observed as occurring in two variations. In the first form, blood is squirted toward a predator. The blood of these animals usually contains toxic compounds, making the behaviour an effective chemical

defence mechanism In psychoanalytic theory, a defence mechanism (American English: defense mechanism), is an unconscious psychological operation that functions to protect a person from anxiety-producing thoughts and feelings related to internal conflicts and ou ...

. In the second form, blood is not squirted, but is slowly emitted from the animal's body. This form appears to serve a deterrent effect, and is used by animals whose blood does not seem to be toxic. Most animals that autohaemorrhage are insects, but some reptiles also display this behaviour. Some organisms have shown an ability to tailor their autohaemorrhaging response. Armoured crickets will projectile autohaemorrhage over longer distances when attacked from the side, compared to being attacked from an overhead predator.

Insects

Six orders of insects have been observed to utilize this defence mechanism. *

Beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s **

Meloidae Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many are conspicuous and some are aposematically colored, announcing their ...

(blister beetles) – their haemolymph contains

cantharidin Cantharidin is an odorless, colorless fatty substance of the terpenoid class, which is secreted by many species of blister beetles. It is a burn agent or a poison in large doses, but preparations containing it were historically used as aphrodisiac ...

that they sequester from plants on which they feed. **

Chrysomelidae The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle ...

, incl. '' Timarcha'' species - their haemolymph contains

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxo ...

s. **

Coccinellidae Coccinellidae () is a widespread family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some entomologists prefer the names ladybird beetles or lady beetles as they ...

(ladybird, ladybug or lady beetles) – An alkaloid toxin in the haemolymph is exuded through the joints of the

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

, triggered by mechanical stimulation (such as predator attack). *

Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...

Cercopidae Cercopidae are the largest family of Cercopoidea, a xylem-feeding insect group, commonly called froghoppers or spittlebugs. They belong to the hemipteran suborder Auchenorrhyncha. Genera A-C *'' Abidama'' *'' Aeneolamia'' *†'' Allocerco ...

– including

spittlebugs The froghoppers, or the superfamily Cercopoidea, are a group of hemipteran insects in the suborder Auchenorrhyncha. Adults are capable of jumping many times their height and length, giving the group their common name, but they are best known ...

Prosapia bicincta ''Prosapia bicincta'', the two-lined spittlebug, is a species of insect in the family Cercopidae. Adults are black with two red or orange lines crossing the wings. It reaches a length of 8–10 mm. It is widespread in the eastern half of th ...

'' and ''Prosapia ignipectus'' *

Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...

Sawfly Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...

larvae *

Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...

Tiger moth The de Havilland DH.82 Tiger Moth is a 1930s British biplane designed by Geoffrey de Havilland and built by the de Havilland Aircraft Company. It was operated by the Royal Air Force (RAF) and other operators as a primary trainer aircraft. ...

adults, such as ''

Arctia caja The garden tiger moth or great tiger moth (''Arctia caja'') is a moth of the family Erebidae. ''Arctia caja'' is a northern species found in the US, Canada, and Europe. The moth prefers cold climates with temperate seasonality, as the larvae ove ...

'', which mixes haemolymph with glandular products (neurotoxic choline esters). *

Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...

** Bushhoppers, such as '' Dictyophorus spumans'', '' Phymateus viridipes'' and '' Phymateus leprosus'' – their haemolymph contains cardiac

glycosides In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

, sequestered from

milkweed ''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to humans ...

on which they feed. **

Katydid Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifera, t ...

s, including '' Eugaster'' species ** Armoured ground crickets **'' Enyaliopsis nyala'' * Plecoptera **

Stonefly Plecoptera is an order of insects, commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the mo ...

larvae

Reptiles

Tropidophis_curtus_barbouri_autohaemorrhaging

Lizards

* Horned lizards (

Phrynosomatidae The Phrynosomatidae are a diverse family of lizards, sometimes classified as a subfamily (Phrynosomatinae), found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny ...

). At least six species of horned lizards are able to squirt an aimed stream of blood from the corners of their eyes, up to 5 feet (1.5 m).

Snakes

* West Indian wood snake (''

Tropidophis ''Tropidophis'', common name wood snakes or West Indian wood snakes,Hampton Wildman Parker, Parker HW, Grandison AGC (1977). ''Snakes — a Natural History''. Second Edition. London and Ithaca: British Museum (Natural History) and Cornell Univers ...

''). Thirteen species have been found to expel blood from the mouth and nostrils while also fully flooding both eyes with blood. * European grass snake (''

Natrix natrix The grass snake (''Natrix natrix''), sometimes called the ringed snake or water snake, is a Eurasian non-venomous colubrid snake. It is often found near water and feeds almost exclusively on amphibians. Subspecies Many subspecies are recogni ...

''), which secretes blood from the lining of the mouth while playing dead. * Long-nosed snake ('' Rhinocheilus lecontei''), which exudes blood from the cloaca. * Eastern hognose snake ( ''Heterodon'' ''platirhinos''), which emits blood from the cloacal region. * Plain-bellied water snake (''

Nerodia erythrogaster ''Nerodia erythrogaster'', commonly known as the plain-bellied water snake or plainbelly water snake, is a familiar species of mostly aquatic, nonvenomous, colubrid snake endemic to the United States. Description The plain-bellied water snake ...

''), which releases blood from the mouth.

Consequences of reflexive bleeding

In some cases, the loss of blood can be substantial. Beetles may lose up to 13% of their net body weight as a consequence of expelling haemolymph. Autohaemorrhaging may result in dehydration. The ejection of blood puts organisms at risk of cannibalism from conspecifics. Canibalism - Reflex bleeding (2106637702)

Canibalism - Reflex bleeding (2106637702)

References

External links

*{{commonscat-inline, Autohaemorrhaging, Autohaemorrhaging Antipredator adaptations Blood Insect physiology