Spider cannibalism


Spider cannibalism

acrificial fathers

It is often said that the male (usually significantly smaller than the female, down to 1% of her size as seen in "Tidarren sisyphoides") is likely to be killed by the female after the coupling, or sometimes even before intercourse has been initiated. This supposed propensity is what gave the black widow spider, "Latrodectus mactans", its name. However, the three species of North American black widows do not seem to usually kill the male (although they have been known to). Males can sometimes even live in the web of a female for a while without being harmed in any way. The male Australian redback spider "Latrodectus hasselti" is killed by the females after it inserts its second palpus in the female genital opening; in over 60% of cases the female then eats the male.

Although the male "Latrodectus hasselti" may sometimes die during mating without the female actually consuming it, this species represents a possible strategy of "male sacrifice". The male redback, while copulating, 'somersaults' and twists its abdomen directly onto the fangs of its mate. Most males get consumed at this stage (Maydianne CB Andrade reports 65%).Andrade, Maydianne C.B. "Behavioral Ecology" (2003), 14:531–538] Males that 'sacrifice' themselves gain the benefit of increasing their paternity relative to males who do not get cannibalized.

However, despite these examples and many other similar reports, the theory of the 'sacrificial male' has become greater than the truth. Mating of spiders is not always followed by cannibalism. Foelix writes, "The supposed aggressiveness of the female spider towards the male is largely a myth... only in some exceptional cases does the male fall victim to the female." Foelix, Rainer F. "Biology of Spiders", 1982.] Michael Roberts says, "It is rare for a fit male to be eaten by the female."Roberts, Michael J. "Spiders of Britain and Northern Europe", Collins, London, 1995.] And yet, spider cannibalism has been proved to occur in some species more than in others, mainly species belonging to "Latrodectus".

There has always been speculation on why this sacrifice of male mates might occur despite the fact that there is an obvious disadvantage to the sacrificial males. One theory is that once the male has mated, he is unlikely to mate again and so any further extension of his life is of lesser evolutionary benefit than his indirectly contributing nutrition to the eggs. Having more offspring would give the male the advantage of having his genes passed on over other males that might avoid being eaten. This scenario would be consistent with the hypothesis of Roberts that old or unfit males get eaten, whilst younger and fitter ones may survive to mate again.

acrificial mothers

*Offspring of the species "Stegodyphus lineatus" eat their mother.

Non-reproductive cannibalism

Some spiders, such as "Pholcus phalangioides", will prey on their own kind when food is scarce. Also, females of "Phidippus johnsoni" have been observed carrying dead males in their fangs.

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Cannibalism (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 speciesIn …   Wikipedia

  • Spider bite — redirects here. For The Spider Bite urban legend, see The Spider Bite. Spider bite Classification and external resources Chelicerae of a black wishbone (nemesiid) spider, a mygalomorph …   Wikipedia

  • Spider web — Spider s Web redirects here. For other uses, see Spider s Web (disambiguation). Spiral orb webs in Karijini, Western Australia …   Wikipedia

  • Spider — Taxobox name = Spiders image width = 250px image caption = an Orb weaver spider, Family: Araneidae regnum = Animalia phylum = Arthropoda subphylum = Chelicerata classis = Arachnida ordo = Araneae ordo authority = Clerck, 1757 diversity link =… …   Wikipedia

  • Spider Baby — Infobox Film name = Spider Baby image size = caption = Film poster director = Jack Hill Bart Patton (assistant) producer = Paul Monka Gil Lasky writer = Jack Hill narrator = starring = Lon Chaney Jr. Sid Haig Jill Banner Beverly Washburn music =… …   Wikipedia

  • Sexual cannibalism — This article is about arthropod behavior; for the human psychological disorder see sexually motivated cannibalism Sexual cannibalism is a special case of cannibalism in which a female organism kills and consumes a male of the same species before …   Wikipedia

  • Redback spider — Taxobox name = Redback spider image width = 250px image caption = Female Redback spider regnum = Animalia phylum = Arthropoda classis = Arachnida ordo = Araneae familia = Theridiidae genus = Latrodectus species = L. hasselti binomial =… …   Wikipedia

  • Tangle web spider — Taxobox name = Tangle web spiders image width = 250px image caption = Steatoda bipunctata fossil range = Cretaceous [Grimaldi,D.A. et al. Fossiliferous Cretaceous Amber from Myanmar (Burma): Its Rediscovery, Biotic Diversity, and Paleontological… …   Wikipedia

  • Black widow spider — Taxobox name = Black widow image width = 211px regnum = Animalia phylum = Arthropoda classis = Arachnida ordo = Araneae suborder: Labidognatha familia = Theridiidae genus = Latrodectus subdivision ranks = Species subdivision = L. mactans… …   Wikipedia

  • Alternate versions of Spider-Man — In addition to his mainstream incarnation, Spider Man has had been depicted in other fictional universes. Alternate continuities Other related characters exist in alternate versions of the Marvel Universe. These include: Ultimate Spider Man… …   Wikipedia