February 2, 2017

ANT NAVIGATION

Ants are small insects. Their brains are no bigger than the size of a pin-head. Most ant species live in large groups, or colonies. Their homes are called nests. Many ants are known to travel long distances from their nests. Yet, they are clever enough to always find their way back.

Previous research suggests that many ants follow scent trails. These are chemical signals called phero-mones. Ants release these chemicals from their bodies. As well as trails, pheromones are used to commu-nicate with fellow ants. Scientists from Britain and France have com-pleted some experiments with the Cataglyphis velox ant. This insect, they say, seems to navigate by us-ing different parts of memory at the same time.

Ants are believed to have evolved from wasp-like insects. This prob-ably happened between 130 mil-lion and 110 million years ago. So far, at least 12,500 ant species have been recorded, or identified. Some researchers believe that another 10,000 are yet to be discovered. Ants can be found almost every-where except Antarctica. They are very strong. Ants can lift 20 times their own body weight. (If a person was able to do this, they could pick up a big car.)

Most ants are red or black. Some are a green or shiny metallic color. The smallest ant colonies contain about 100 insects. The largest con-tain many millions of ants. In each colony there are different kinds of ant. Many colonies have one queen. Some have more. The queen spends most of the time producing eggs. Most ants in a colony are sterile females. They cannot reproduce. These ants are either “workers”

or “soldiers”. Workers build and maintain the nest and search, or for-age, for food. They also look after the larvae (baby ants), which hatch from the queen’s eggs. Soldier ants defend the nest from any attackers. Male ants are called drones. They have wings. The drones’ only task is to mate with the queen.

A Cataglyphis velox ant (Michael Mangan / Hugh Pastoll)

The smallest ants are about 0.03 inches (0.75 millimeters) long. The bullet ant is one of the largest. Worker bullet ants are 1.2 inches (30 millimeters) long. These ants live in parts of Central and South America. Their name comes from their bite, or sting. The pain caused by a bul-let ant’s bite is said to be 30 times worse than a bee sting. What’s more, it spreads to all parts of the body. Some people say that a bite from a bullet ant “is the worst pain known to man”. The effect of the bite lasts for about three to four hours. Bullet ants do not attack people. They bite only to defend themselves.

Cataglyphis velox is a type of de-sert ant. It is found in parts of Spain. These ants travel far from their nests in search of food. The scientists set up a number of experiments. When a dead insect or other type of food is found, an ant will take it back to the nest. If the item is small, the ants walk forwards. If larger, the ants have to drag it. This means that they walk backwards. When

walking backwards, the ants stop every so often. They look around and then continue dragging the food item. The scientists also “moved” the Sun. They did this by using mir-rors. When the Sun “moved”, the ants went in the wrong direction.

The scientists believe that their experiments suggest that “ant navi-gation” may be more complex than previously thought. These ants seem to use different types of memory at the same time. They recall the route forwards. The ants remember to pick up the food item after putting it down. At the same time, they check the “movement” of the Sun and its position in the sky.