Ants

Earlier this month, a group of scientists described a newly discovered ant species, Colobopsis explodens, in the journal ZooKeys. As the name suggests, the worker ants of the species, which is found in south-east Asia, are known to explode when attacked, releasing sticky, toxic fluid from their abdomens. The explosion kills the ant, which sacrifices itself to protect its nest mates.

Termites

Another example of autothysis, or defensive suicidal rupturing, can be found in Neocapritermes taracua. These termites, native to French Guiana, build up an explosive “backpack” of toxic blue crystals throughout their lifetimes. When the nest is attacked, the older workers release saliva that mixes with the crystals to produce a yet-more toxic liquid to repel invaders.

Mice

Usually mice run for their lives when they sense a cat is near. Some mice, however, show no fear even as the cat goes in for the kill. This seemingly suicidal behaviour is in fact caused by the parasite Toxoplasma gondii, which infects the mouse and turns off its innate fear of cats. If the cat eats the mouse, the parasite reproduces – and the infection can spread to humans as toxoplasmosis.

The giant Pacific octopus

Giant Pacific octopuses are semelparous, meaning they reproduce only once. Once the task is completed, they enter a state of deterioration, during which males are known to move about aimlessly in open water, leaving themselves vulnerable to predators, while the female stops feeding and dies almost immediately after its eggs have hatched.

Bees

It’s well known that when a worker honey bee stings its victim, it does so at the cost of its life: the barbed stinger lodges in the skin, tearing away from the bee’s abdomen with fatal consequences. This is only the case with thicker-skinned creatures such as mammals, however: the same bee could sting another insect without harming itself.