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 is com ...

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

defense mechanism In psychoanalytic theory, defence mechanisms are unconscious psychological processes that protect the self from anxiety-producing thoughts and feelings related to internal conflicts and external stressors. According to this theory, healthy ...

. 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

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

Beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

s ** Meloidae (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. Its main current use in pharmacology is treating molluscum contagiosum and warts topically. It is a burn agent ...

that they sequester from plants on which they feed. One of the known species is '' Meloe americanus''. **

Tenebrionidae Darkling beetle is the common name for members of the beetle family Tenebrionidae, comprising over 20,000 species in a cosmopolitan distribution. Taxonomy ''Tenebrio'' is the Latin generic name that Carl Linnaeus assigned to some flour beetles ...

(darkling beetles) - larvae of '' Asbolus verrucosus'' have been observed to autohaemorrhage while they feign death. **

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

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

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Several isomers exist but these terms usually refer to 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein th ...

s. **

Coccinellidae Coccinellidae () is a widespread family (biology), family of small beetles. They are commonly known as ladybugs in North America and ladybirds in the United Kingdom; "lady" refers to Mary, mother of Jesus, mother Mary. Entomologists use the ...

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

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

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

Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...

** Cercopidae – including spittlebugs ''

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

'' and ''Prosapia ignipectus'' *

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

** Tiger moth adults, such as '' Arctia caja'', 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 – gras ...

** Bushhoppers, such as '' Dictyophorus spumans'', ''

Phymateus viridipes ''Phymateus viridipes'', also known as the green milkweed locust or African bush grasshopper, is an African locust in the family Pyrgomorphidae (gaudy grasshoppers). Body characteristics It is about long at maturity and capable of long migrat ...

'' 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 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, the ...

s, including '' Eugaster'' species and '' Acanthoplus discoidalis'' *

Plecoptera Plecoptera is an order (biology), 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 b ...

** Stonefly 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 Caribbean dwarf boas, wood snakes or West Indian wood snakes,Hampton Wildman Parker, Parker HW, species:Alice Georgie Cruickshank Grandison, Grandison AGC (1977). ''Snakes — a Natural History''. Second Edition. Lond ...

''). 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''), 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''), which releases blood from the mouth. * Western hognose snake ('' Heterodon nasicus''), 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 other members of their species.

References

External links

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