vertically-migrating shrimplike prawn is not a true (Caridean) shrimp
of abdominal segment 2 do not overlap those of abdominal segments 1 and
3. Also, the gills are dendrobranchiate (featherlike--photo)
instead of platelike (phyllobranchiate) gills as seen in true
shrimp. As with most sergestids the rostrum
is short, less than 1/10 the length of the carapace
(photo) and the first
have tiny chelae
The tiny rostrum
points obliquely upward and forward and has an blunt tip (photo).
Both the carapace
and the abdomen are slender and laterally compressed, especially the
abdominal segment. There are no spines just behind and above
or behind and below the eye (hepatic)
The eyestalks have a tubercle
on their inner (medial)
have very long antennae, with the proximal portion of the flagellum
rigid and extending forward and laterally, then a sharp kink, and a
long flexible section that trails back beside the animal's body through
the water. The fragile antennae are often damaged or lost
capture, as happened with the animal shown here. The carapace
of live individuals is red and purple, the abdomen is red.
are clear. The animal may have bioluminescent photophores (in
experience, it has very few) but not a bioluminescent organ of
Total length: Males to 6.3 cm, females to 7.5 cm.
Sergia tenuiremis (Kroyer, 1855)
Common name(s): Ocean sergestid
(shrimp--not a formal taxonomic category)
|Sergia tenuiremis captured below 500
m depth off Point Conception,
CA, Sept 1992. This photo is of a preserved specimen which
its darker original color. The animal has also lost its long,
second antennae which are longer than the body.
|(Photo by: Dave Cowles Oct
How to Distinguish from
at shallower depths and has a bioluminescent organ of pesta.
on the eyestalks but it does have a supraorbital
and a hepatic
spine on the carapace.
is pointed and the body is partly transparent.
Atlantic, Indian oceans
570-1000 m or deeper
species is widespread but not as common as are many other bathypelagic
crustaceans along our coast. Near the Canary Islands it
vertically migrate to near the surface at night. Sergestids
through the midwater, using their long antennae to detect vibrations of
potential prey which they grasp with their pereopods.
Cowles, David L.; Childress, James J.; Wells, Mark E., 1991.
Metabolic rates of midwater crustaceans as a function of depth of
off the Hawaiian Islands: Food availability as a selective
Marine Biology 110: pp. 75-83
Flock,M.E.; Hopkins,T.L., 1992. Species composition,
distribution, and food habits of the sergestid shrimp assemblage in the
eastern Gulf of Mexico. J. Crustacean Biology 12:2 pp.
Foxton, P., 1969. The morphology of the antennal
certain of the penaeidea (Decapoda,Natantia). Crustaceana
Kikuchi,T.; Nemoto,T., 1986. List of pelagic
from the Western North Pacific. Bulletin of Biogeographical
of Japan 41:7 pp. 51-59
Pearcy,W.G.; Forss,C.A., 1966. Depth distribution of
(Decapoda;Natantia) off Oregon. J. Fisheries Research Board
23:8 pp. 1135-1143
General Notes and
Observations: Locations, abundances,
This closeup of the side of the carapace
shows the dendrobranchiate (branching like a feather) gills
This gill pattern is characteristic of dendrobranchiate decapods such
Penaeids but is not seen in true shrimp or in crabs.
As in most seregestids, the rostrum
is very short. Unlike Eusergestes
similis, the rostrum
of Sergia tenuiremis is
blunt. There are no supreaorbital
spines on the carapace.
there is a tubercle
on the medial
eyestalks in Sergia tenuiremis. In this
view the animal is
The pleopods are feathery and used for swimming. This view is
of pleopods 2-4 (from left to right)
Authors and Editors of Page:
Dave Cowles (2006): Created original page