Cannibalism in Animals: Why Parents Sometimes Eat Their Own Offspring.

According to ТСН: Eating one’s own offspring is a strange phenomenon that actually occurs in the animal kingdom more often than one might think. Filial or brood cannibalism has been observed in fish, insects, spiders, small mammals, and even in some cases, domestic animals.

Behavioral ecologist Anish Bose from the Swedish University of Agricultural Sciences explains that this behavior is part of the reproductive strategies of many species, rather than a random event.

Scientists already know of over 1500 species of animals where cannibalism has been observed. Paradoxically, this process often happens alongside caring for the offspring: parents who guard their eggs or feed their young sometimes may also eat them. As Bose points out, reproduction is an investment, and different species allocate resources between survival and the number of offspring differently.

Features of Cannibalism in Animals

The animals that resort most to cannibalism are those that reproduce slowly, such as whales or elephants, which give birth to and raise one calf for an extended period. In contrast, species with large litters and shorter reproductive cycles more frequently practice partial cannibalism—eating only a few offspring. This helps the survivors obtain more food or reduce overpopulation. Research on carrion beetles back in the 1980s showed that, in resource-scarce conditions, parents sacrifice part of their offspring for the benefit of the rest.

Among mammals like cats, dogs, or pigs, cannibalism can involve non-viable or stillborn young. This allows males to regain energy spent on pregnancy and birth. Other factors influencing this behavior include stress, disease, and parasites.

Conflict of Interests Between Parents

Partial cannibalism of the brood may also be linked to genetic competition. In some species of fish, males increase cannibalism if they “believe” that part of the brood does not belong to them. This happens due to chemical signals released during hatching. A study on the bluebanded damselfish in 2003 showed that males recognizing offspring of another male respond with increased cannibalism.

Thus, there is a conflict of interests: the female guards the eggs while the male patrols the territory, allowing him to control the situation and prevent the offspring from being eaten in contradiction to the female's interests. Another form is full brood cannibalism, where parents destroy all young in dangerous or unfavourable conditions. This strategy allows the male to survive and try to reproduce again when conditions become safer.

Despite decades of research, most data pertains to fish and laboratory animals. According to Bose, science is just beginning to understand how complex the reasons for this behavior are. Researchers believe that offspring cannibalism is not an exception but a widespread adaptive mechanism, and many discoveries lie ahead to help understand how and why it arises.

As a reminder, scientists have developed an alternative to oil-based plastic that safely dissolves in the ocean.