Ants are social insects that live in highly organized colonies, exhibiting complex behaviors for group survival. Their actions, from foraging to nest building, are often driven by the collective well-being of the colony. These tiny creatures demonstrate remarkable adaptations, making their interactions within the colony a subject of ongoing scientific interest.
Ant Cannibalism
Ants engage in cannibalism, consuming members of their own species. This behavior is not their primary food source but occurs under specific circumstances. While active predation on live, healthy ants within the same colony is rare, consuming deceased or weakened members is more common. Species like wood ants, carpenter ants, and fire ants exhibit these tendencies. This behavior is a survival mechanism, not a regular dietary choice.
Reasons for Ant Cannibalism
One primary driver for cannibalism in ant colonies is resource scarcity. When external food sources are depleted or the colony faces starvation, ants may consume nestmates for necessary nutrients. For example, a wood ant colony trapped in an old nuclear bunker survived by feeding on dead nestmates due to a lack of other food. This behavior provides a source of protein and other nutrients.
Colonies also practice cannibalism for health management. Eliminating sick, injured, or dead individuals prevents disease spread within the densely populated nest. This hygienic practice helps maintain the colony’s overall health and stability. Consuming these individuals reclaims valuable proteins and other nutrients.
Cannibalism can also be a stress response, emerging as a survival mechanism under extreme environmental stress. If a colony is deprived of protein, cannibalism increases, ceasing when protein is reintroduced. Ant larvae may also engage in cannibalism, targeting eggs from different families to strengthen one family over others. Male larvae cannibalize eggs more frequently than female larvae, suggesting a benefit like increased survival.
What Happens to Deceased Ants
Cannibalism is not the only outcome for deceased ants; other behaviors are more prevalent. A common behavior is necrophoresis, where ants carry dead individuals away from the nest. This sanitation helps prevent disease spread throughout the colony. Dead ants are often taken to a “graveyard” or waste pile away from the nest.
Ants identify dead nestmates by detecting changes in their chemical signature. Live ants have specific compounds on their cuticle that disappear about an hour after death. The absence of these “life signals” triggers necrophoric behavior. This allows for rapid corpse removal before significant decomposition, limiting pathogen spread.
Deceased ants are treated as waste, similar to other refuse generated by the colony. If not removed by necrophoresis or consumed, their bodies naturally decompose through fungi and bacteria outside the nest. This waste management system, including necrophoresis, maintains colony hygiene and minimizes exposure to threats.