Mantis shrimp — such as Gonodactylus smithii — are top predators with excellent vision.

Mantis shrimp — such as Gonodactylus smithii — are top predators with excellent vision. Roy L. Caldwell/UC Berkeley

Evolution

Insect-like brain region found in crustacean group

‘Mushroom bodies’ associated with learning were thought to be exclusive to insects.

Mantis shrimp have a type of brain structure associated with memory and learning that has previously been identified only in insects.

Although insects evolved from crustaceans, the latter were thought to lack the brain centres known as mushroom bodies that are common in insects. Nicholas Strausfeld at the University of Arizona in Tucson and his colleagues analysed the brains of a range of crustaceans and identified insect-like mushroom bodies in mantis shrimp, such as Gonodactylus smithii. These animals typically show more sophisticated behaviour in activities such as hunting and visual recognition than other crustaceans do.

Mushroom bodies may have evolved in the ancestor of crustaceans and insects, say the authors, and then been lost in animals such as crabs and lobsters. But it is also possible that similar structures evolved separately in both insects and mantis shrimp.