Autohaemorrhaging
Action of animals deliberately ejecting blood from their bodies
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Through Blood
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 by a predator overhead.
Insects
Several orders of insects have been observed to utilize this defence mechanism.
- Beetles:
- Meloidae (blister beetles) – their haemolymph contains cantharidin that they sequester from plants on which they feed. One of the known species is Meloe americanus.
- Tenebrionidae (darkling beetles) – larvae of Asbolus verrucosus have been observed to autohaemorrhage while they feign death.
- Chrysomelidae, incl. Timarcha species – their haemolymph contains anthraquinones.
- Coccinellidae (ladybirds, ladybugs, lady beetles) – An alkaloid toxin in the haemolymph is exuded through the joints of the exoskeleton, triggered by mechanical stimulation (such as predator attack).
- Hemiptera:
- Cercopidae – including spittlebugs Prosapia bicincta and Prosapia ignipectus
- Lepidoptera:
- Tiger moth adults, such as Arctia caja, 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 on which they feed.
- Tettigoniidae (katydids and bush crickets), including Eugaster species and Acanthoplus discoidalis (armoured katydid, armoured bush cricket)
- Plecoptera:
- Stonefly larvae
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Reptiles
Lizards
- Horned lizards (Phrynosomatidae). 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), 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.