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Autohaemorrhaging, or reflex bleeding, is the action of animals deliberately ejecting
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 cir ...
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 o ...
. 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 aphrodisia ...
that they sequester from plants on which they feed.
** Chrysomelidae, 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-dioxoan ...
s.
** Coccinellidae (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
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''
*†'' Allocer ...
– 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 lay ...
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
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
** Bushhoppers, such as '' Dictyophorus spumans'', '' Phymateus viridipes'' and '' Phymateus leprosus'' – their haemolymph contains cardiac 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.
** Katydids, including '' Eugaster'' species
** Armoured ground crickets
**'' Enyaliopsis nyala''
* Plecoptera
** Stonefly larvae
Reptiles
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''). 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''), 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.
See also
* Autothysis *Haemorrhage
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...
References
External links
*{{commonscat-inline, Autohaemorrhaging, Autohaemorrhaging Antipredator adaptations Blood Insect physiology