Exploding Ants - How Do They Explode?
- bioworld090
- Mar 11, 2023
- 3 min read
Exploding ants are a group of ants in the family Formicidae that inhabit the forests of Asia. They are found in Malaysia, Thailand and Borneo.
They make their nests mostly on dipterocarp tree canopy and their colonies can contain thousands of individuals.
There are 15 recognized species of exploding ants that are collectively placed under the species complex Colobopsis cylindricus (COCY). The species Colobopsis explodens is the model species for the group and will be studied further to understand more about the exploding ant group.
THE ABILITY TO EXPLODE
Exploding ants, as the name implies, have the ability to explode and by an explosion, it doesn't mean that they blast with a loud sound like an explosive. Here, explosion means that these ants have the ability to rupture a particular structure of their body to release certain substances for a certain purpose.
The "explosion" of exploding ants is an example of autothysis. Autothysis, also known as suicidal altruism or self-sacrifice, is an extreme form of altruistic behaviour. It is seen in social animals such as insects that live in colonies. The term was first used by Ulrich Maschwitz and Eleonore Maschwitz in 1974 to describe the exploding behaviour of a particular species of exploding ant, Colobopsis saundersi.
Why do exploding ants explode?
Exploding ants explode in defense. This is a defensive mechanism that is specifically effective against arthropods. When threatened or attacked, these ants sacrifice themselves for their colony by rupturing their body.
Do all castes of exploding ants have the ability to explode?
Ants and other colonial insects have different castes in their colonies. In simple terms, a caste is a group of individuals within the same species with different morphology or function. For example, ants in a colony can be basically divided into different castes such as the queen, workers and defenders. The caste system in insects is complex and there are many limitations to dividing individuals into different castes based on just morphology or function.
Only minor workers (all sterile females) are equipped with this ability to explode. They have enlarged mandibular glands that extend from their head to their gaster (the bulbous posterior portion). The mandibular gland contains a sticky and irritant substance that is released during the explosion.
How do exploding ants explode?
When threatened or attacked, exploding ants stick to the attacker and contract their muscles rapidly which results in the rupture of their mandibular gland and the release of the inner contents through their gaster. The yellow, sticky and irritant substance released has a spice-like odor and binds to the threat causing distress, immobility and even death.
ADVANTAGES AND DISADVANTAGES OF THIS DEFENSIVE BEHAVIOUR
ADVANTAGES:
Effective in immobilizing and killing other insects.
A single minor worker can disable more than one or multiple small attackers.
DISADVANTAGES:
This defensive behavior is not effective against large predators such as lizards and birds.
As the defense includes the explosion of ants, it also kills the minor workers, therefore reducing their number in a colony.
OTHER BEHAVIOURS OF MINOR WORKERS
Researchers have observed minor workers spending a significant amount of time on the leaves of the tree they live. While it was previously hypothesized to contribute to nutrition, a new hypothesis suggests that it is more of a monitoring and patrolling behavior.
Minor workers also spend a significant time on tree bark grazing on the mosses, lichens, algae, fungi and yeasts. This behavior is suggested to contribute to their nutrition. They have also been observed to eat dead insects.
MAJOR WORKERS
The C. explodens ants have another caste, the major workers, that helps in the defense of the colony. Unlike the minor workers that explode in defense, major workers close the entrances leading into the colony. Major workers have a unique head shape that allows them to plug the entrances.
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