Category: Feeding Behavior.
In a few societies, cannibalism is a cultural norm. The eating of a person from the same community is called endocannibalism, and this form of cannibalism, often ritual, is a part of the grieving process of the society. It can be seen as a way of guiding the souls into the living bodies of the community. Exocannibalism is the eating of someone not in the same society, usually after the person has been defeated in battle. Both types of cannibalism feature the belief that the eater takes on some of the characteristics of the dead person.
3 female Mormon crickets eating another Mormon cricket. © Sionnach.
It is generally as the last resort
In most societies, though, cannibalism is only a last resort, for extreme circumstances only. The shipwreck survivors of the Essex and the Medusa in the 19th century are thought to have eaten their dead comrades. This is necrocannibalism, rather than homicidal cannibalism, as the person is already dead. Under UK law, killing someone for food, even in extreme situations, is seen as a crime. Two men in England were found guilty of murder after killing and eating a cabin boy while adrift in a lifeboat, and this case set the precedent that starvation is no defense for murder charges.
Jeffrey Dahmer and Albert Fish
We have several examples of murderers eating their victims, often for some perverse sexual gratification. Good (if that’s the right word) examples include Jeffrey Dahmer and Albert Fish. These men were seen as mentally ill, although the compulsion to eat human meat isn’t formally recognized as a mental disorder. There are also some rare cases of self-cannibalism, or autophagia.
An example sexual cannibalism: a female European mantis eating its male partner. © Oliver Koemmerling.
Sexual cannibalism occurs in the animal kingdom, and is usually the case of the female eating the male before, during or after mating. Spiders and praying mantises are the best-known examples of animals that practice sexual cannibalism. There are several theories that may explain why this happens.
She could be hungry
One idea is that eating the male is easy food, and the female decides whether she will benefit more from the male’s nutrients than from mating with him. She can always go on to find another mate later. It’s more likely that a hungry female will rate the nutritional value of the male higher than his genetic value, so full females are less likely to eat the male.
He could be ugly looking
Females might use cannibalism as a way of eliminating unattractive males, or to control the timing of copulation. Spiders have been observed to behave more aggressively towards less attractive males than they do towards more suitable examples. Males who look similar to the female are less likely to be eaten, for example.
By far the simplest theory for sexual cannibalism is mistaken identity – the male is seen as dinner before he’s recognized as a potential mate. This doesn’t work for most spider species though, as they have elaborate and lengthy (as well as risky) courtship rituals which should leave the ladies in no doubt about the intentions of their gentlemen callers.
Size does matter
Female spiders are usually larger than the males, and this size difference varies widely between species. This means that male spiders are often more vulnerable to attack from females if they are significantly smaller.
Relationship between organisms
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