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Objects of beauty
It really does not take a lot
of imagination to suppose
the harlequin shrimp gets
its common name from its
numerous bold, clownish spots.
Though these vivid markings
vary somewhat from region to
region, the harlequin shrimps
may be divided into two
distinct groups, which are now
recognised by most taxono-
mists to be separate species
(and the only two members of
the genus). Hymenocera elegans
typically has a whitish or cream
body with rich, reddish-brown
blotches in bluish margins; H.
picta typically has a white body
with pink or magenta blotches
in yellow margins. In both spe-
cies, this spotting covers most
of the body as well as the ani-
mal’s enlarged, flattened claws.
Stripes of the same colours run
down the legs. A patch of tiny
speckles may cover parts of the
head and tail appendages.
Females often bear stripes that
run along the underside of the
tail. With a very broad midsec-
tion and deeply hunched tail,
its body is markedly less elon-
gate in shape than most other
shrimps. Large, conspicuous,
petal-shaped sensory append-
ages top the head. It is fairly
average in size for a shrimp,
generally not attaining much
more than five centimetres
in length. Females tend to be
slightly larger than males.Widespread, thinly
Harlequin shrimps occur widely
across the tropical Pacific
Ocean, from Southern Japan
and the Clipperton island chain
to Polynesia, northern Australia,
East Africa and the Red Sea. H.
elegans is found mainly within
the Indo-Pacific region, while
H. picta is found mainly within
the Central and Eastern Pacific
regions. The major habitat typesThe pickiest of eaters
Given the large variety and
sheer numbers of starfishes pre-
sent on most coral reef habitats,
it is surprising how few animals
are specialised to prey on them.
There are only a few starfish-
eating shrimps. The bumblebee
shrimp (Gnathophyllum ameri-
canum) and the bongo shrimp
(Phyllognathia ceratophthalma),
for example, are known to claim
starfishes as their main fare.
But (at least among regularly
imported aquarium species)
the harlequin shrimp is the only
obligate starfish-eater. They are,
in fact, so thoroughly adapted
physically to preying on starfish
that it may be difficult for them
to find, consume and digest
other food sources. Still, it is
even more probable that they
are so adapted behaviorally
to this form of predation thatfor both species can be charac-
terised as quiet, inshore, rocky,
shallow (1-20 metres depth),
subtidal areas that are over or
adjacent to coral reefs. Because
Hymenocera spp. is distributed
so broadly, one might make
the assumption that they are
abundant. In actual fact, they
are (like so many other highly
specialised species) somewhat
rare in any one locale. It is
reasonable to guess that theirpopulation sizes are largely
restricted to the availability of
their preferred starfish prey
species.There are numerous, but usually very pretty, colour variants among Hymenocera spp. Photo by Elias Levy.A dominant individual successfully defends its meal against a smaller rival. Photo by Kenneth Wingerter.