Can Ants Swim?

Ants are small and light, so a drop of water is a big obstacle for them. Can they swim? Most ants are not real swimmers, but many are much better at surviving water than you might think.

A living raft of black imported fire ants (Solenopsis richteri) floating on the water.

Floating and paddling

Because ants are so light, they usually float on the surface of the water. Their body is covered with a waxy layer and tiny hairs that repel water. Many ants can paddle slowly to the edge, and some can survive under water for a surprisingly long time because they need very little oxygen.

Fire ant rafts

The most famous water trick belongs to fire ants. When their nest floods, the workers grab each other with their jaws and legs and form a living raft, with the queen and the brood safe on top. In experiments by researchers in the United States, ants formed such a raft within two minutes after being put in water. Ants at the bottom are not drowned: tiny hairs trap a thin layer of air around their bodies. In the wild such rafts can drift for weeks until they reach dry land. Living in the US? Read why we do not recommend keeping fire ants.

Ants that dive

• Camponotus schmitzi lives inside a carnivorous pitcher plant on Borneo. It dives into the fluid in the pitcher to grab drowned insects, something very few ants do.

• Polyrhachis sokolova from Australia lives in mangroves that flood every day with the tide. It can swim, and the colony survives under water in air pockets in its nest.

What it means in your formicarium

For small ants and young colonies, a drop of water can still be a trap. That is why it matters not to make the nest too wet and to use a well-plugged water reservoir in a test tube. Read our tips on the perfect test tube setup. A large test tube with a test tube stopper makes a good, safe start.

Sources

• National Geographic, 2011. Fire ants build life rafts to survive floods. PNAS.

Photo: © Melissa McMasters