Hymenodora frontalis Rathbun 1902

Biology/Natural History: This bathypelagic species lives very deep in midwater. Its exoskeleton is so soft that it is often damaged on capture. Note that it has unusually large eggs for an Oplophorid shrimp. It is one of the most common deepliving Oplophorid shrimp off British Columbia. It is not a vertical migrator.

Bathypelagic

Geographical Range: Pribilof Islands, Bering Sea to San Clemente Island, CA

Depth Range: 200 to 3000 m

This is a true shrimp from the family Oplophoridae, which lives in deep midwater offshore. True shrimp have the second abdominal epimera overlapping that of segment 1 and 2. Family Oplophoridae is almost entirely midwater and has exopodites on its pereopods. Hymenodora are deepliving, non-vertically migrating species that have almost no pigment in their small eyes, giving them a golden color, and usually have very soft exoskeletons. None of their abdominal segments has a median dorsal ridge. H. frontalis has a longer rostrum than the other local Hymenodora species. The rostrum extends past the cornea of the eye and even past the peduncle of the first antennae. The eyestalk has a strong tubercle on the median side near the cornea. The telson is truncate instead of rounded at the end, and has terminal spines. Unlike the other Oplophorids, which tend to be dark red in deepliving species and half red in vertical migrators, the color of Hymenodora is orange-red, darker on carapace and on eggs. Maximum length: To about 58 mm.

How to Distinguish from Similar Species: The rostrum of H. frontalis is longer than that of other Hymenodora, extending beyond the peduncle of the first antennae.

Known from seamounts and knolls