Autohaemorrhaging

Autohaemorrhaging, or reflex bleeding, is the action of animals deliberately ejecting blood from their bodies. Autohaemorrhaging has been observed as occurring in two variations.[1] 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.[1] Most animals that autohaemorrhage are insects, but some reptiles also display this behaviour.[2]

Horned lizard exhibiting autohaemorrhaging.

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.[3]

Insects

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

Reptiles
A West Indian wood snake displaying autohaemorrhaging. The eyes are fully flooded with blood and some drops expelled through the mouth.

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).[7]

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.[8]
  • European grass snake (Natrix natrix), which secretes blood from the lining of the mouth while playing dead.[9]
  • Long-nosed snake (Rhinocheilus lecontei), which exudes blood from the cloaca.[10]
  • Eastern hognose snake (Heterodon platirhinos), which emits blood from the cloacal region.[10]
  • Plain-bellied water snake (Nerodia erythrogaster), which releases blood from the mouth.[10]
  • 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.[11] Autohaemorrhaging may result in dehydration. The ejection of blood puts organisms at risk of cannibalism from conspecifics.[12]

An inactive prepupa Asian ladybeetle autohaemorrhaging, resulting from cannibalism by an adult of the same species.

See also

References
  1. Iftime, Alexandru; Iftime, Oana (January 2014). "Thanatosis and autohaemorrhaging in the Aesculapian Snake Zamenis". Herpetozoa. 26 (3–4): 173–174 – via Zobodat.
  2. Bateman, P. W.; Fleming, P. A. (2009). "There will be blood: autohaemorrhage behaviour as part of the defence repertoire of an insect". Journal of Zoology. 278 (4): 342–348. doi:10.1111/j.1469-7998.2009.00582.x. ISSN 1469-7998.
  3. Bateman, Philip W.; Fleming, Patricia A. (2012-04-26). "Signaling or Not-Signaling: Variation in Vulnerability and Defense Tactics of Armored Ground Crickets (Acanthoplus Speiseri: Orthoptera, Tettigoniidae, Hetrodinae)". Journal of Insect Behavior. 26 (1): 14–22. doi:10.1007/s10905-012-9329-5. ISSN 0892-7553. S2CID 18599346.
  4. The Alkaloids: chemistry and physiology, Volume 31 By Arnold Brossi
  5. Thompson, Vinton; Carvalho, Gervasio S. (2016). "Abrupt Geographical Transition between Aposematic Color Forms in the Spittlebug Prosapia ignipectus(Fitch) (Hemiptera: Cercopidae)". Psyche: A Journal of Entomology. 2016: 1–10. doi:10.1155/2016/3623092.
  6. V.H. Resh, R.T. Cardé (2003) Encyclopedia of Insects. p. 168
  7. Sherbrooke, Wade C.; Middendorf III, George A. (2001). "Blood-Squirting Variability in Horned Lizards (Phrynosoma)". Copeia. 2001 (4): 1114–1122. doi:10.1643/0045-8511(2001)001[1114:BSVIHL]2.0.CO;2. ISSN 0045-8511.
  8. Hoefer, Sebastian; Mills, Sophie; Robinson, Nathan J. (2019). "Autohaemorrhaging in a Bahamian pygmy boa, Tropidophis curtus barbouri". Herpetological Bulletin (150): 39–40. doi:10.33256/hb150.3940.
  9. Gregory, Patrick T.; Isaac, Leigh Anne; Griffiths, Richard A (2007). "Death feigning by grass snakes (Natrix natrix) in response to handling by human "predators."". Journal of Comparative Psychology. 121 (2): 123–129. doi:10.1037/0735-7036.121.2.123. ISSN 1939-2087. PMID 17516791.
  10. Smith, Donald D.; Pflanz, Deborah J.; Powell, Robert (1993). "Observations of autohemorrhaging in Tropidophis haetianus, Rhinocheilus lecontei, Heterodon platyrhinos, and Nerodia erythrogaster". Herpetological Review. 24: 130–131.
  11. Klowden, Marc J. (October 2007). Physiological Systems in Insects. Vol. 2. Elsevier. p. 369. doi:10.1016/c2011-0-04120-0. ISBN 9780124158191.
  12. Bateman, Philip W.; Fleming, Patricia A. (2012-04-26). "Signaling or Not-Signaling: Variation in Vulnerability and Defense Tactics of Armored Ground Crickets (Acanthoplus Speiseri: Orthoptera, Tettigoniidae, Hetrodinae)". Journal of Insect Behavior. 26 (1): 14–22. doi:10.1007/s10905-012-9329-5. ISSN 0892-7553. S2CID 18599346.
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