FROM DESPERATION TO SEX: REASONS FOR CANNIBALISM

Desperation: In times of famine, some animals go to desperate measures to stay alive, including eating members of their own species. For example, crocodiles have been known to eat their offspring when no other food is available.

Nutrition: Mormon crickets migrate on mass during food shortages and if one stops marching, others will devour it, because their fellow katydid is a good source of protein and salt, needed by the insects. Cannibalism is a convenient way to get all the nutrients an animal needs, but they run the risk of more easily catching diseases.

Female rattlesnakes eat stillborn or non-viable offspring to recover some of their strength, Discover reported.

Mormon crickets (stock image) migrate on mass during food shortages and if one stops marching, others will devour it, because their fellow katydid is a good source of protein and salt, needed by the insects

Crab spiders eat eggs and their mother over the course of weeks until she is immobile and dies, Science News reported, allowing offspring to be heavier and to have a better chance at survival.

Stress: Stressed screech owls have been known to eat a mate when adapting to a new environment, although the behaviour is rare.

Sand sharks 

Sex: Male Australian redback spiders are often eaten by females during copulation. While the male perishes, the copulation time is extended, increasing his chance of passing on his genes. The act isn't unusual in spiders and some insects such as the praying mantis.

Survival of infants: In what is perhaps the ultimate competition for food, sand sharks eat their younger siblings while still in the womb to give themselves the best chance of survival.

Tiger salamanders come in two larval forms - normal and cannibalistic. The cannibals develop faster and have wider jaws and sharper teeth to chomp on their siblings.

Dominance and competition: Male lions sometimes kill a younger lion that is challenging leadership of the pride. If the young imposter wins, he may kill cubs to make room for his own offspring.

In 1977, famous conservationist Jane Goodall reported cannibalism in male and chimpanzees. It was presumed for years that the act was unusual, but in 2007, experts came to the conclusion that it was a behaviour designed to cut competition for food and mates, after seeing gentler female chimps eating others.

Mystery: Sometimes experts have no idea why one animal eats another. Keepers at Smithsonian’s National Zoo in Washington DC saw a mother sloth bear eating one of her own cubs. The mother, named Khali, had raised offspring before, leaving experts baffled as to what prompted her to eat the small bear.