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Like rays and sharks, skates belong to a family called
elasmobranchs, which includes all fish with a skeleton made entirely of
cartilage. One of the more common species of skate found in
Narragansett Bay is the little skate. Its body is shaped like a
flattened, rounded triangle and is well adapted for life on the bottom
of the Bay. The skate is armored with sharp spines along the back and
tail that are used as a defensive measure of protection. Females have
more spines than the males.
Unlike bony fish, skates lack a mechanism to pump oxygenated water
over their gills. Because skates spend most of their lives on the
bottom, they breathe through specialized organs called spiracles, which
are slitlike openings near their eyes. Water is taken in through the
spiracles, passes over the gills, and then leaves the body through five
pairs of gill slits underneath the body.
The skate has many rows of blunt teeth, resembling sandpaper, that
help grind food between two well-developed jaw plates. Skates feed on a
diverse diet of shellfish, crabs, sea sqirts, worms, amphipods, squid,
and small fish.
Male skates can be distinguished by two long claspers along their
pelvic fins, which they use to hold onto the female and transmit sperm.
Little skates copulate many times in a year. The female lays two large
eggs that develop inside a capsule, or egg case, which is often found
attached to seaweed. The empty black capsules wash ashore after the
young skates have hatched. Resembling square coin purses with prongs at
each corner, the capsules are commonly called "mermaid's purses."
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Raja erinacea
