The crustacean order Tanaidacea (known as tanaids) make up a minor group within the class Malacostraca.

The thoracic limbs wash water towards the mouth, filtering out small particles of food with the mouthparts or maxillipeds.

Some species actively hunt prey, either as their only food source, or in combination with filter feeding.

The early developmental period is spent while young are within the marsupium of the mother.

[1] The oldest representatives of the group are known from the Carboniferous, with modern forms emerging during the Mesozoic.