This is a true
shrimp from the family Oplophoridae, which lives in deep midwater
True (Caridean) shrimp have the second abdominal epimera
overlapping that of segment 1 and 2. Family Oplophoridae is
entirely midwater and has exopodites
on its pereopods
non-vertically migrating species that have almost no pigment in their
eyes, giving them a golden color (photo,
and usually have very soft exoskeletons (they are frequently damaged
captured by net). None of their abdominal segments has a
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 (photo,
The eyestalk has a strong tubercle
on the median side near the cornea (photo).
instead of rounded at the end, and has terminal spines (photo).
Unlike the other Oplophorids, which tend to be dark red in deepliving
and half red in vertical migrators, the color of
Hymenodora is orange-red,
darker on carapace and on eggs. Maximum length: To
Hymenodora frontalis Rathbun, 1902
Common name(s): Pacific ambereye
Caridea (true shrimp)
|A female Hymenodora frontalis
carrying eggs. Caught 1000-1500
m depth off Pt. Conception, CA. Note the yellowish eye,
of black pigment, and the large egg size.
|(Photo by: Dave Cowles,
How to Distinguish from
Similar Species: The
of H. frontalis is longer than that of other Hymenodora,
extending beyond the peduncle
of the first antennae (see photo,
Geographical Range: Pribilof
Sea to San Clemente Island, CA
Depth Range: 200
to 3000 m
species lives very deep in midwater. Its exoskeleton is so
it is often damaged on capture. Note that it has unusually
eggs for an Oplophorid shrimp. It is one of the most common
Oplophorid shrimp off British Columbia. It is not a vertical
TH (1980) Shrimps of the Pacific Coast of Canada. The
of Fisheries and Aquatic Sciences 202: 1–280
Fenner A., 1986. The Caridian Shrimps (Crustacea:
of the Albatross Philippine Expedition, 1907-1910, Part 4:
Oplophoridae and Nematocarcinidae. Smithsonian Contributions
Number 432. Paperback, 82 pp.
Wasmer, Robert A., 1967. Bathypelagic shrimps (Penaeidea and
Caridea) from the eastern North Pacific. Master's thesis,
College, College Place, WA. 86 pp.
General Notes and
Observations: Locations, abundances,
Another photo of a gravid female. Photo by Dave Cowles in San
Clemente Basin, CA, 1996. Caught at 1000-1500 m depth.
female was captured in San Clemente Basin, CA in May 1966.
from a video by Dave Cowles. Click Here
to see the video
This side view of a preserved specimen shows the rostrum
which extends well beyond the corneas
of the eyes and even exceeds the peduncle
of the first antenna.
Note also the pereopods. Oplophorids, unlike most other
of true shrimp, has exopods (exopodites) on its pereopods.
of the pereopods are short,
curved backward and used for swimming. The endopodites of the
pereopods are longer, extended forward, and used for manipulating
The eye pigment in Hymenodora is always pale, even
In this closeup dorsal view of the head, the median tubercles
on the eyestalks near the corneas
can be seen. From a presereved specimen.
This is a closeup dorsal view of the telson
and uropods. The uropods are shorter than the telson
and fringed with long setae. The telson
(not rounded) on the end, with two long spines at the corners (one of
is broken off on this individual). Photo of a preserved
Authors and Editors of Page:
Dave Cowles (2005): Created original page