Snapping shrimp live in colonies with a queen, much like bees
Eusociality, the peak of animal social life with queens, workers and shared nurseries, is best known in ants, bees and termites. But it also appears in a reef shrimp whose single breeding female is guarded by claw-snapping males, and possibly in naked mole-rats. Some scientists have even argued that humans qualify.
Sociality describes how strongly animals of a species gather in groups and cooperate. It arises as a survival strategy: a mother wasp that stays by her nest makes it harder for parasites to eat her larvae, and biologists suspect such pressures shaped behaviour in the wasp family Vespidae. The foundation is parental investment, spending time and energy on offspring at the cost of future breeding. An animal that tends its young but shows no other social traits is called subsocial, a pattern that has evolved independently many times among winged insects.
The vocabulary grew from bee research. Suzanne Batra coined eusocial and quasisocial in 1966, and Charles Michener built a classification in 1969 adding subsocial, communal and semisocial. Jaguars meet only to mate. Solitary-but-social species such as mouse lemurs, lorises and orangutans forage alone yet may share sleeping sites, with female ranges overlapping. In communal groups adults share a nest but raise their own young; quasisocial ones share brood care as well; semisocial ones add a caste split between breeders and non-breeders.
Full eusociality adds overlapping adult generations caring for young together, and at its most refined, castes with fixed body forms. It occurs in ants, bees, wasps, sawflies and termites, plus a beetle, an aphid-like bug and thrips. Synalpheus regalis snapping shrimp live in sponge-dwelling kin groups defended by males with enlarged claws. Naked and Damaraland mole-rats, inbred colonies raised by one queen, may be primitively eusocial, though a 2008 study found they sometimes outbreed to found new colonies. Whether a permanently sterile caste is required is debated, and in 2005 E. O. Wilson and Bert Hölldobler controversially argued humans count.
Social living seems linked to brainpower: hyenas and lions beat leopards and tigers on puzzles needing innovation. Eusocial species are rarer than presocial ones but have outsized populations. Even solitary labels are being revisited; decades of collar data on South Texas bobcats, from 1985 to 2024, found 102 cases of overlapping home ranges and less mutual avoidance than expected. Some lone dolphins, such as Fungie, who lived from 1983 to 2020, shun their own kind but seek out people.
Source: Sociality
