Alicella gigantea is the largest species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of amphipod

Amphipoda

Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...

 ever observed, with some individuals reaching up to 340 millimetres (13.4 in) long. Formerly included in the family Lysianassidae

Lysianassidae

Lysianassidae is a family of marine amphipods.-Genera:*Abyssorchomene*Acheronia*Acidostoma*Acontiostoma*Adeliella*Alicella*Allogaussia*Ambasia*Ambasiella*Ambasiopsis*Apotectonia*Aristiopsis...

, a new family, Alicellidae, was erected in 2008 for Alicella and five related genera. The species only lives 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 plain

Abyssal plain

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest...

s of both Atlantic

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

s. One specimen was found in the stomach of a black-footed albatross

Black-footed Albatross

The Black-footed Albatross, Phoebastria nigripes, is a large seabird from the North Pacific of the albatross family Diomedeidae. It is one of three species of albatross that range in the northern hemisphere, nesting on isolated tropical islands...

, but is thought to have been dead before it was eaten.