Noncommercial benthic fauna

Eastern Bering Sea



Phylum Mollusca, class
Gastropoda, orders Mesogastropoda and Neogastropoda

Species Representatives: Some of the more abundant large gastropods in the SE Bering Sea are Neptunea pribiloffensis, N. heros, N. ventricosa, N. lyrata, Fusitriton oregonensis, Pyrulofusus deformis, Volutopsius fragilis, Buccinum angulosum, B. scalariforme, and B. polare.

Distribution and Life History: In the SE Bering Sea, the gastropods that leave large calcareous shells behind when they die are members of the "true snail" Orders Mesogastropoda and Neogastropoda. These spirally-shelled molluscs are widely distributed across the SE Bering Sea shelf (MacIntosh, 1980). The multitude of SE Bering Sea species range in length from a few millimeters up to 20 cm (Kessler, 1985). While the dead shell biomass and ecological importance of the small species is no doubt considerable, it is generally the shells fifty mm or more in length that are retained in the NMFS survey trawl. This size range is dominated across most of the shelf by the four large Neptunea spp. In the NMFS trawl survey database, the "empty gastropod shell" category does not include the large amount of dead shell that has been commandeered by hermit crabs. That shell is weighed and counted as part of the hermit crab biomass. In some areas, virtually all trawl-caught shell is occupied by hermit crabs. Similarly, shells that are dwarfed by the size of invertebrates attached to them are often not separated from those invertebrates, thus are not accounted for as empty gastropod shell.

Gastropod shell is important both as cover for motile (free-living) organisms, and attachment substrate for sessile (attached) organisms. The 16 species (Kessler, 1985) of hermit crabs in the NMFS SE Bering Sea survey area are particularly dependant on gastropod shell. Many other SE Bering Sea invertebrates, including polychaetes, slipper shells, tunicates, hydroids, bryozoans, sponges, and anemones commonly live in and on gastropod shell. Gastropod egg cases are also commonly laid on gastropod shell.