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 th ...

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 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 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 ''Timarcha'' is a genus of leaf beetles in the family Chrysomelidae, with more than 100 described species in three subgenera. The most widely known species is ''T. tenebricosa'', the bloody-nosed beetle. All species are black, wingless organisms ...

'' 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-dioxoan ...

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 the ...

(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 ** Cercopidae – including spittlebugs '' Prosapia bicincta'' and ''Prosapia ignipectus'' * Hymenoptera **

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 l ...

larvae * Lepidoptera **

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'', 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 – grass ...

** Bushhoppers, such as ''

Dictyophorus spumans ''Dictyophorus spumans'', the koppie foam grasshopper or , is a species of grasshopper in the family Pyrgomorphidae indigenous to Africa. The name "foaming grasshopper" derives from the insect's ability to produce a toxic foam from its thoracic ...

'', ''

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 ''Phymateus'' is a genus of grasshoppers of the family Pyrgomorphidae. Description Species of the genus ''Phymateus'' are African grasshoppers about long. Some species at maturity are capable of long migratory flights. They raise and rustle win ...

'' – their haemolymph contains cardiac glycosides, sequestered from milkweed on which they feed. ** Katydids, including '' Eugaster'' species **

Armoured ground cricket The Bradyporinae are a subfamily in the family Tettigoniidae (bush crickets or katydids), based on the type genus '' Bradyporus''. First described as a family, "Bradyporidae" (Burmeister, H., 1838), the first use as Bradyporinae was by Brunner v ...

s **'' Enyaliopsis nyala'' *

Plecoptera 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 mos ...

** 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 spin ...

). 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''). 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 ''Rhinocheilus'' is a genus of snakes, commonly called the long-nosed snakes, in the family Colubridae. The genus is native to the western United States and Mexico. Species and subspecies The genus ''Rhinocheilus'' contains the following specie ...

''), 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.

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