Description: This is a true shrimp from
the family Oplophoridae, which lives in deep midwater offshore. True
(Caridean) shrimp have the second abdominal epimera overlapping that of
segment 1 and 2. Family Oplophoridae is almost entirely midwater,
has exopodites on its pereopods, and pereopods 1 and 2 are longer and more
stout than the others. 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 (photo)
(they are frequently damaged when captured by net). None of their
abdominal segments has a median dorsal ridge. H. gracilis has a
short rostrum which extends only slightly beyond the cornea of the eye,
maxilliped 2 has a podobranch and an epipod, and the side of the carapace
has a V-shaped groove with the apex directed ventrally. It has a
groove passing upward and backward from the middle of the hepatic groove
but no groove converging toward the first from the supra-branchial groove.
The telson has 4 pairs of dorsolateral 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:
Hymenodora gracilis Smith, 1886
Caridea (true shrimp)
|Hymenodora gracilis from 2000-2500 m depth 100 mi off
Pt Conception, CA. Total length about 5-6 cm.
|(Photo by: Dave Cowles, 1993)
How to Distinguish from Similar Species:
Hymenodora frontalis has
a longer rostrum which extends up to or beyond the distal end of the antennal
peduncle. H. glacialis has no podobranch on the epipodite
of maxilliped 2 and has no V-shaped groove on the side of the carapace.
Depth Range: Bathypelagic
Wasmer, Robert A., 1967. Bathypelagic shrimps (Penaeidea and Caridea)
from the eastern North Pacific. M.S. thesis, Walla Walla College,
College Place, WA. 86 pp.
General Notes and Observations: Locations, abundances,
A closeup of the same individual as above. Notice the amber eye,
which has very little pigment, and the thin, filmy exoskeleton through
which the animal's yellowish muscles can be seen.
Authors and Editors of Page:
Dave Cowles (2006): Created original page