Download Short-spined brittle star

Short-spined
brittle star
Scientific Name: Ophioderma brevispina
Field Markings: Green or brown in color
Size: Diameter of the central disc is about half an inch,
with an arm length reaching 2.5 inches
Habitat: Tide pools, under rocks or shells
Seasonal Appearance: Year-round
DISTINGUISHING FEATURES
AND BEHAVIORS
The short-spined brittle star is an echinoderm, usually
green or brown in color. Its spine lies flat against its arms,
with seven short spines on either side of each arm joint. The
diameter of the central disc is about half an inch, with an arm
length of one and a half to two and a half inches long; however,
their size is dependent on their predation.
The word “brittle” means “easily breakable.” These creatures
are so named because they have the ability to shed a limb in an
instant to avoid predation. Like their echinoderm relatives, they
are also able to regenerate body parts.
Brittle stars do not rely on their tube feet for movement.
Rather, they use their five long, whiplike arms, which are capable
of fast, snakelike motions. These inverts are very flexible, highly
mobile and easily camouflaged among plants. They can be seen
at night in large groups crawling along the sea floor.
Brittle stars feed mostly on decaying material and plankton.
They have no eyespots like other sea stars, but are able to sense
some light through their body.
There are over 2,000 species of brittle stars found throughout
the world. They are often found in tide pools, hiding in algae
and under rocks or shells or, sometimes, disguised in dark, heavy
algal mats from Cape Cod south.
RELATIONSHIP TO PEOPLE
Scientists have found brittle stars to be sensitive to polarized
light and the species may be used as an indicator of harmful
levels of ultraviolet radiation.
HOW TO GET YOUR OWN COPY
RISAA members can purchase their own copy of The
Uncommon Guide To Common Life on Narragansett Bay
for $15 from the RISAA Merchandise Committee. Stop by
the committee table at any monthly RISAA meeting.
P.O. Box 763
Londonderry, NH 03053
Tel: 603-434-4689
Fax: 603-432-3902
E-mail:
[email protected]
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