Deep-sea near-bottom swarms of pelagic amphipods Themisto: observations from submersibles

Swarms of Themisto abyssorum and one of Themisto libellula (Hyperiidea, Hyp eriidae) were observed during four dives of Mir deep-sea manned submersible s in the Norwegian and Greenland Seas at depths of about 1000 m. Concentrat ions of the amphipods in the most dense swarm were as high as 25-38 individ uals per cubic meter in the layer 100-5 m above the bottom. However, such s warming does not seem to be obligatory for Themisto. The animals picked up (food?) particles directly from the seabed.