Sea Cucumbers—Really Cool Animals!
From Jane Ellis
Sea Cucumbers are really cool animals
found in tidal pools, scattered on our
beach after storms, and even burrowed
in the pluff mud of the Kiawah River.
These soft, elongated “cigar” shaped
organisms are first cousins to sea
urchins, sand dollars, and sea stars
all belonging to the group of marine
invertebrates called echinoderms. Most
echinoderms have radial symmetry,
spiny skin, and tube feet but don’t have
an anterior (head) and posterior (tail)
region. Sea cucumbers have all these
traits and a head area with a mouth
(most often surrounded by a cluster
of retractable tentacles used to collect
food), a tubular body, and a rear section
with an opening at the end of a long-
coiled intestines called the anus.
These common benthic (bottom
dwelling) animals also have some
unusual characteristics. For one,
their branched respiratory tubules
open through the rear of the body at
the anus. Water is pulled (breathed)
in and then expelled after gases and
excretory products are exchanged.
Another interesting feature is that
sea cucumbers can “eviscerate” their
respiratory tubules, intestine and other
internal organs through this opening
as a defense mechanism. The mass
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of long tangled, sticky threads may
contain toxins such as “holothurin”.
Not to worry, the sea cucumber can
regenerate these body parts in two to six
weeks. Although sea cucumbers have
no distinct sensory organs, they are
very sensitive to touch and can “harden”
their bodies and squirt water when
picked up by a predator.
Sea cucumbers normally move
slowly scavenging detritus (decayed
organic matter) and plankton for
food performing the important
environmental task of recycling
nutrients. Certain species burrow and
extend their tentacles into the current
to collect “food” as it passes. In some
oceans these animals travel in herds
along the ocean floor processing tons
of sediments as they move. But they
are easy prey for animals not affected
by their toxins such as large mollusks,
fish, crabs, lobsters and even sea
turtles. Besides being a food source,
some species are hosts for a variety of
flatworms, crabs, snails and small fish.
For example, pearlfish are known to
inhabit their posterior intestinal tract
and can often be seen darting in and out
of a sea cucumber’s rear opening.
From intertidal zones and shallow
seas to the deepest sea floors sea
cucumbers can be found in all the
world’s oceans. There are over 1,200
species of these invertebrates who are
usually four to twelve inches long but
the smallest species is less than half an
inch in length and the largest up to six
feet long.
Sea cucumbers have been used as
food and medicine for over a thousand
years. Today you can find them fresh
(raw), dried, smoked, powdered,
fried, fermented, in soups and stews
especially in Asia, Japan and the
Indo-Pacific region. Called “beche-
de-mer,” “Trepang,” or “gamat” these
animals are considered delicacies and
are highly prized—so much so that
certain species are over harvested. In
the past they were believed to have
aphrodisiac and restorative properties.
Recently researchers have found that
sea cucumbers contain an impressive
array of vitamins, minerals and unique
bioactive compounds that might have
anti-inflammatory, anticancer, anti-
hypertension and wound healing
actions.
Striped sea cucumbers (Thyonella
gemmata), Pentamera pulcherrima,
and brown or hairy sea cucumbers
(Sclerodactyla briarius) are common
in our area. NK
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