Alicella gigantea is the largest species of amphipod ever observed, with some individuals reaching up to 34 centimetres (13 in) long.

[5] The species lives only at great depths; the first specimens were collected at the end of the 19th century from the Madeira Abyssal Plain, and subsequent specimens have been found in other abyssal plains of both the Atlantic and Pacific Oceans,[6] as well as from the Kermadec Trench in the southwest Pacific.

[3] One specimen was found in the stomach of a black-footed albatross, but is thought to have been dead before it was eaten.

[6] The size of this species of amphipod is hypothesized to be connected to oxygen availability.

[7] These additional structures allow for A. gigantea to absorb more oxygen, which is a known contributor to gigantism.