Invertebrates
Ant
Formicidae · also called ants
An ant on its own is almost nothing — it cannot reproduce, and it will not survive long alone. The real animal is the colony: a queen who does nothing but lay eggs, and thousands of sterile daughters who do everything else, working together so tightly that biologists treat the whole nest as one organism.
Overview
Ants are the family Formicidae, around 14,000 named species, on every continent except Antarctica. Every ant lives in a colony with a long-lived queen, brief winged males, and a sterile female workforce, sometimes split into workers, majors, and soldiers. Together the world’s ants make up an estimated 15 to 25 per cent of the weight of all land animals.
How a colony works
Ants coordinate almost entirely through pheromones — scent trails, alarm signals, recruitment cues — so a colony can pour its workers onto a food find within minutes. There is no ant in charge; the colony’s behaviour emerges from many simple local interactions, like thought from neurons.
Farmers, weavers, and storage jars
Leafcutter ants have farmed a fungus underground for 50 million years. Weaver ants sew leaf nests with silk from their own larvae. Army ants build bridges from their bodies, and honeypot ants keep living workers as food stores. A queen can live 10 to 30 years.
Status
Ants as a family are Not Evaluated. Most are common, but some narrow-range species are threatened, and invasive ants such as the Argentine ant and the red imported fire ant are among the world’s most damaging introduced species.
Ant: common questions
Why is an ant colony called a superorganism?
Because the colony, not the individual ant, is the unit that grows, reproduces, defends itself, and competes, and its parts are as specialised and interdependent as the organs of a body. The queen is the reproductive system, laying all the eggs; the workers are the muscles, the digestive system, the immune system, and the sensory organs, foraging, feeding the young, nursing, building, and fighting; and no single ant can survive or reproduce alone. Decisions such as where to nest or which food source to exploit emerge from many simple local interactions between workers following chemical rules, without any ant being in charge, much as behaviour emerges from neurons in a brain. This is why the colony is often treated as a single organism spread across thousands of bodies.
Do ants really farm and keep livestock?
Yes, several groups do, and they were doing it long before people. The fungus-growing ants of the Americas, including the leafcutters, cut and carry vegetation into underground chambers, chew it into a pulp, and grow a specific fungus on it that only they cultivate, feeding the colony on the fungal tissue and defending the garden from weeds and pests with the help of an antibiotic-producing bacterium on their bodies. Separately, many unrelated ants tend aphids, scale insects, and treehoppers, protecting them from predators and moving them to fresh plants in exchange for the sugary honeydew the insects excrete, an arrangement that works much like herding cattle for milk.
How strong is an ant?
Very strong for its size, though the popular figure needs care. Many ants can lift and carry objects several times their own body weight in their jaws, and some can hold many times more than that when the load is hung from the jaws while the ant is anchored. This is not because ant muscle is special but because of scaling, since as an animal gets smaller, its muscle cross-section, which sets strength, shrinks more slowly than its volume, which sets weight, so small animals are proportionally much stronger. A human scaled down to ant size would show similar feats. Ant necks in particular are built to take enormous forces, which is why an ant can run while carrying a load bigger than itself clamped in its mandibles.
What is the difference between an ant and a termite?
They are not closely related and only look alike because both are small, pale-to-dark, social insects that live in large colonies in wood or soil. Ants are in the order Hymenoptera, related to wasps and bees, with a narrow waist, elbowed antennae, and hard bodies, and in a mature colony the workers are all female. Termites are more closely related to cockroaches, with a straight, thick waist, straight beaded antennae, and soft pale bodies, and their worker and soldier castes include both sexes. Ecologically termites are mainly wood and plant-litter decomposers, while ants are predators, scavengers, seed collectors, and farmers, and ants are in fact among the main predators of termites.