Depending on the species, workers in a colony can be

1. Monomorphic, all the same size.
2. Dimorphic, of two sizes.
3. Polymorphic, more than two sizes.

Workers divide labor, so some leave the nest to find food while most of them stay in the nest to take care of all of the other tasks which need to be done.

A newly eclosed adult worker ant: The exoskeleton of a callow worker is still relatively soft and lightly pigmented.

"Eclose" refers to the emergence of an adult insect from a pupal case or an insect larva from an egg.

A member of the subcaste of the largest workers; especially, in ants: With ants, the subcaste of major workers is usually specialized for defense, so that an adult belonging to it is often also referred to as a "soldier".

In polymorphic ant series involving three or more worker subcastes: A media worker is one individual ant belonging to the medium-sized subcaste, or subcastes.

A dwarf worker produced from either the first ant broods or later ant broods that have been subjected to starvation: Nanitic workers occur in both monomorphic and polymorplhic species.