Cannibalism (zoology)

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Three Mormon crickets eating a fourth Mormon cricket
Three Mormon crickets eating a fourth Mormon cricket

In zoology, cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded for more than 1500 species[citation needed] (this estimate is from 1981, and likely a gross underestimation).

Unlike previously believed, cannibalism is not just a result of extreme food shortage or artificial conditions, but commonly occurs under natural conditions in a variety of species[1].[2] [3]In fact, scientists have acknowledged that it is ubiquitous in natural communities. Cannibalism seems to be especially prevalent in aquatic communities, in which up to ~90% of the organisms engage in cannibalism at some point of the life cycle. Cannibalism is also not restricted to carnivorous species, but is commonly found in herbivores and detritivores.[4]

Contents

[edit] Sexual cannibalism

This female Stagmomantis carolina is eating her mate. Sexual cannibalism occurs in roughly one quarter of all intersexual encounters of this species.
This female Stagmomantis carolina is eating her mate. Sexual cannibalism occurs in roughly one quarter of all intersexual encounters of this species.[5]
Main article: Sexual cannibalism

Sexual cannibalism is a special case of cannibalism in which a female organism kills and consumes a conspecific (same species) male before, during, or after copulation. Rarely, these roles are reversed.[6][7] Sexual cannibalism has been recorded in the female redback spider, black widow spider, praying mantis, and scorpion, among others.

[edit] Size structured cannibalism

Size structured cannibalism, in which large individuals consume smaller conspecifics, is more common. In such size-structured populations, cannibalism can be responsible for 8% (Belding's Ground Squirrel) to 95% (dragonfly larvae) of the total mortality,[8] making it a significant and important factor for population [9] and community dynamics[10]. Such size structured cannibalism has commonly been observed in the wild for a variety of taxa.

[edit] Cannibalistic infanticide

Further information: Infanticide (zoology)

Another common form of cannibalism is filial cannibalism (a form of infanticide) where parents eat their own young. Classical examples include the chimpanzees where groups of adult males have been observed to attack and consume conspecific infants[11],[12] [13]and cats[1], elephants, dogs, baboons, lions, where adult males commonly kill infants when they take over a new harem after replacing the previous dominant males[14][15]. In agricultural settings, pigs are known to eat their own young, accounting for a sizeable percentage of total piglet deaths.

One, perhaps surprising, example is the bottlenose dolphin, which has been reported to kill its young through impact injuries.[16] Another example is hamsters eating their young. Dominant male langurs tend to kill the existing young upon taking control of a harem.[17] There has been sight of infanticide in the leopard population[18].

Particularly in fish, one can discern

  • total filial cannibalism, where a parent eats the whole brood
  • cases where a parent eats only part. E.g. sand gobies Potamoschistus minutus can eat 40% of their eggs without reducing the outcome of their reproductive efforts.[19]

[edit] Intrauterine cannibalism

Intrauterine cannibalism is a behaviour in some carnivorous species, in which multiple embryos are created at impregnation, but only one or two are born. The larger or stronger ones consume their less-developed siblings as a source of nutrients.

In adelphophagy, the fetus eats sibling embryos, while in oophagy it feeds on eggs.[20]

Intrauterine cannibalism is known to occur in lamnoid sharks[21] and in the Fire Salamander,[22] as well as in some teleost fishes.[20] The Carboniferous chimaera, Delphyodontos dacriformes, is suspected of having practiced intrauterine cannibalism, also, due to the sharp teeth of the recently born (or possibly aborted) juveniles (adults are unknown), and the presence of fecal matter in the juveniles' guts.[23]

[edit] References

  1. ^ G. A. Polis, The evolution and dynamics of intraspecific predation. Annual Review of Ecology and Systematics 12, 225-251 (1981).
  2. ^ Laurel R. Fox, Cannibalism in natural populations. Annual Review of Ecology and Systematics 6, 87-106 (1975).
  3. ^ M. A. Elgar and B. J. (eds) Crespi, Cannibalism: Ecology and evolution among diverse taxa. (Oxford University Press, New York, 1992).
  4. ^ Laurel R. Fox, Cannibalism in natural populations. Annual Review of Ecology and Systematics 6, 87-106 (1975).
  5. ^ Mike Maxwell. Sexual cannibalism, mate choice, and sperm competition in praying mantids.
  6. ^ Kenwyn Blake Suttle (1999). The Evolution of Sexual Cannibalism. University of California, Berkeley.
  7. ^ Min-Li Tsai & Chang-Feng Dai (2003). Cannibalism within mating pairs of the parasitic isopod Ichthyoxenus fushanensis (abstract page). Journal of Crustacean Biology 23 (3): 662–668. doi:10.1651/C-2343. 
  8. ^ G. A. Polis, The evolution and dynamics of intraspecific predation. Annual Review of Ecology and Systematics 12, 225-251 (1981)
  9. ^ David Claessen, A. M. De Roos, and L. Persson, Population dynamic theory of size-dependent cannibalism. Proceedings of the Royal Society of London Series B-Biological Sciences 271 (1537), 333-340 (2004)
  10. ^ V. H. W. Rudolf, Consequences of stage-structured predators: Cannibalism, behavioral effects and trophic cascades. Ecology 88, 2991-3003 (2007)
  11. ^ A. C. Arcadi and R. W. Wrangham, Infanticide in chimpanzees: Review of cases and a new within-group observation from the Kanyawara study group in Kibale National Park. Primates 40 (2), 337-351 (1999).
  12. ^ M. L. Wilson, W. R. Wallauer, and A. E. Pusey, New cases of intergroup violence among chimpanzees in Gombe National Park, Tanzania. International Journal Of Primatology 25 (3), 523-549 (2004).
  13. ^ D. P. Watts, J. C. Mitani, and H. M. Sherrow, New cases of inter-community infanticide by male chimpanzees at Ngogo, Kibale National Park, Uganda. Primates 43 (4), 263-270 (2002)
  14. ^ C. Packer, Infanticide is no fallacy. American Anthropologist 102 (4), 829 (2001).
  15. ^ B.C. Bertram, Social factors influencing reproduction in wild lions. Journal of Zoology 177, 463-482 (1975).
  16. ^ Milius, S. (July 18, 1998), “Infanticide Reported in Dolphins”, Science News 154 (3): 36, <http://www.sciencenews.org/pages/sn_arc98/7_18_98/fob1.htm>. Retrieved on 22 May 2007 
  17. ^ The evolution of infanticidal mechanisms in male langurs, <http://mentor.lscf.ucsb.edu/course/fall/psyc155/langurs-j05.pdf>. Retrieved on 22 May 2007 
  18. ^ Fildes, Jonathan, Cheating cheetahs caught by DNA, <http://news.bbc.co.uk/2/hi/science/nature/6701515.stm>. Retrieved on 30 May 2007 
  19. ^ Bioone Online Journals - Parents Benefit From Eating Offspring: Density-Dependent Egg Survivorship Compensates For Filial Cannibalism
  20. ^ a b Crespi, Bernard; Christina Semeniuk (2004). "Parent-Offspring Conflict in the Evolution of Vertebrate Reproductive Mode". The American Naturalist 163 (5): 635–654. doi:10.1086/382734. 
  21. ^ Hamlett, William C.; Allison M. Eulitt, Robert L. Jarrell, Matthew A. Kelly (1993). "Uterogestation and placentation in elasmobranchs". Journal of Experimental Zoology 266 (5): 347–367. doi:10.1002/jez.1402660504. 
  22. ^ Stebbins, Robert C.; Nathan W. Cohen (1995). A Natural History of Amphibians. Princeton, NJ: Princeton University Press, 9. ISBN 0-69110-251-1. 
  23. ^ Lund, R. 1980. Viviparity and intrauterine feeding in a new holocephalan fish from the Lower Carboniferous of Montana. Science, 209: 697‑699.

[edit] Further reading

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  • M. A. Elgar and Bernard J. Crespi (eds.). 1992. Cannibalism: Ecology and Evolution of Cannibalism among Diverse Taxa Oxford University Press, New York. (361pp) ISBN 0198546505