Invertebrates
Giant Amphipod
Alicella gigantea · also called supergiant amphipod
Growing more than thirty times larger than its shallow-water relatives, a giant amphipod scavenges some of the deepest ocean trenches on Earth, a striking example of just how extreme deep-sea gigantism can become.
Overview
The giant amphipod, Alicella gigantea, is a large scavenging crustacean native to deep ocean trench habitat recorded across multiple ocean basins worldwide. Its dramatically oversized body compared to typical amphipods, tolerance for extreme trench pressure, and role as an opportunistic scavenger make it one of the most striking examples of deep-sea gigantism found anywhere in the ocean.
Size as a survival strategy
Where most amphipods stay small enough to hide in sediment and crevices, the giant amphipod has taken the opposite path, growing large enough to dominate the rare, concentrated feasts that occasionally sink into the crushing depths of the deepest ocean trenches.
Status
Least Concern, though detailed population size and trends remain largely unknown due to the species’ extreme depth habitat.
Giant Amphipod: common questions
How much bigger is the giant amphipod than a typical amphipod?
This species can grow to more than 30 centimetres long, dramatically larger than most amphipod species, which are typically only a few millimetres to a couple of centimetres in size.
Why do some deep-sea animals grow so much larger than their shallow-water relatives?
This species is a well-known example of deep-sea gigantism, a pattern seen in several groups of deep-ocean invertebrates, though the exact causes remain debated among researchers, with theories involving cold temperatures, high pressure, and scarce but occasionally concentrated food sources.
How deep does the giant amphipod live?
This species has been recorded in some of the deepest ocean trenches on Earth, tolerating extreme pressure far beyond what most animals could survive.
How do researchers study the giant amphipod?
This species remains relatively poorly studied, with much of what is known coming from baited traps deployed at extreme ocean depth, since direct observation at such depths is difficult and expensive.