section_path: Other species
section_name: Other species
paragraph_text: Other species
  
  As suicide requires a willful attempt to die, some feel it therefore cannot be said to occur in non-human animals. Suicidal behavior has been observed in Salmonella seeking to overcome competing bacteria by triggering an immune system response against them. Suicidal defenses by workers are also seen in the Brazilian ant Forelius pusillus, where a small group of ants leaves the security of the nest after sealing the entrance from the outside each evening.
  
  Pea aphids, when threatened by a ladybug, can explode themselves, scattering and protecting their brethren and sometimes even killing the ladybug; this form of suicidal altruism is known as autothysis. Some species of termites (for example Globitermes sulphureus) have soldiers that explode, covering their enemies with sticky goo.
  
  There have been anecdotal reports of dogs, horses, and dolphins killing themselves, but little scientific study of animal suicide. Animal suicide is usually put down to romantic human interpretation and is not generally thought to be intentional. Some of the reasons animals are thought to unintentionally kill themselves include: psychological stress, infection by certain parasites or fungi, or disruption of a long-held social tie, such as the ending of a long association with an owner and thus not accepting food from another individual.