Science has discovered that species eat each other, not only as a reproductive process but as part of nature itself. Cannibalism has a bad reputation, but the more scientists learn about it, the more they discover it’s a vital process in nature.
“It’s quite common throughout the animal kingdom,” says biologist Bill Schutt, author of “Cannibalism: A Perfectly Natural History” and professor emeritus of Biology at Long Island University (USA). It’s more common in invertebrates and fish, but cannibalism occurs in all major animal groups.
Many Species Eat Their Parents, Siblings, and Offspring. Why?
There are well-documented cases, including dogs, felines, bears, and primates, where animals have eaten skin, muscles, tendons, and bones, often when trapped. While it can be concerning, sometimes it’s to strengthen the species, as a safety mechanism, for reproduction, or to avoid risks. Here are some examples of why species eat each other:
Within the Family
Many species cannibalize their offspring, usually when a cub is sick, deformed, or born in conditions where the mother can’t produce milk or provide other food. If a cub dies or can’t survive, its body can become a valuable nutrient source for the parent. This is known as filial cannibalism.
Infanticide
In other species, males kill unrelated offspring, a behavior known as infanticide. In these cases, like with the North American red squirrel, males kill and eat offspring that aren’t theirs or whose paternity is uncertain. By doing so, the female becomes fertile again quickly, and the male can protect her from other matings, ensuring the offspring are his. Infanticide also occurs in lions and chimpanzees.
Female sharks carry hundreds of eggs in their two uteri. They mate with multiple males and have offspring from multiple fathers. Within the uterus, developing sharks will eat the remaining unfertilized eggs and eventually their embryonic siblings, a behavior called intrauterine cannibalism. Eventually, only two sharks remain to be born, one in each uterus.
Other Types
Some species, like spiders, employ another form of cannibalism known as matriphagy, where newborns eat their mothers. In a final act of motherhood, the velvet spider dissolves her organs and vomits them for her offspring to consume before they devour her entire body. The last organs to liquefy are the heart and ovaries, a safety mechanism to ensure that if a male eats his offspring, she can mate with him and try again.
This story was written in Spanish by Perla Vallejo in Ecoosfera.
