Amphipod Under Arctic Sea Ice

An amphipod within Arctic sea ice.
S. Harper, UAF, Hidden Ocean 2005, NOAA.

Several species of amphipod like this one, Gammarus wilkitzkii, live permanently within Arctic sea ice. These animals are endemic, meaning they only live here. They acclimate to a wide range of salt levels in the water using a physiological response called osmoregulation.