LITTLE PINK SEA
CUCUMBERS
One of the interesting features of Tybee’s marine biology is how some
species appear in greater abundance than normally expected. I often use
the terms “episodic” or “sporadic” to describe these events. Some winters,
starfish are more abundant than usual, or particular seaweed species
are more common. Some episodes are confined to the season when that
animal normally occurs on Tybee. But other species just suddenly appear
on Tybee in great number regardless of season.
One of the non-seasonal episodic animals on Tybee’s beach is the Pale
Sea Cucumber (although I usually call it “the little pink sea cucumber”).
Most of the time, we don’t see them on the beach; but when they do
appear, they are here in large numbers. They are not a normal resident of
our beach habitats, but rather live offshore in deeper water just under the
sand. Probably what happens is that their offshore, deeper-water habitat
gets disturbed by rough water and they get suspended into the water and
eventually they wash up on the beach. Although somewhat frequently
washed ashore, surprisingly they are not featured in most field guides of
shoreline animals of the southeast coast (look for Cucumaria pulcherrima
or Pentamera pulcherrima). When washed ashore, we will see them in the
wet intertidal sand of flat sections of the beach or in shallow tide pools.
Pale Sea Cucumbers are only 1-2 inches long, pale pink, and have five
double rows of short, orange tube feet (with suckers on the end) along
their fragile body. They use the tube feet to attach to small shells for
camouflage and to adhere onto surfaces. Generally, they are shaped like a
tiny cucumber. But it can change its shape and size as it accumulates or
releases water and contracts longitudinal and circular muscles, so it may
be round/spherical or long and oval, and often it might be slightly curved.
12 TYBEE BEACHCOMBER | JUNE 2020
To slowly move through the bottom, a Pale Sea Cucumber will constrict its
circular muscles to form a distinct ring around its body near its posterior
end, and then gradually move the constriction forward. This process pushes
its anterior end forward.
With its body buried just under the sand, a Pale Sea Cucumber can
extend a small ring of tentacles out of its anterior end for feeding. I’m not
sure what it feeds on (deposits in the sandy bottom, or as a filter feeder
of plankton in the water). And I have to be honest, I haven’t been curious
enough to do a gut dissection yet! One more thing that they (and other
sea cucumbers) will do that is sort of interesting and a little gross is when
irritated or threatened, it might eviscerate (throw up its insides); but it can
regenerate them. I’m guessing that these little Pale Sea Cucumbers must
not taste good because even the sea gulls and other shore birds don’t seem
to eat them even though they are sometimes laying there by the hundreds.
Dr. Joe Richardson (Ph.D. Marine Sciences) is a retired marine science
professor with 40 years of research and teaching experience along GA, the
southeastern coast and Bahamas. Besides research, he conducts Tybee
Beach Ecology Trips (www.TybeeBeachEcology.com) and frequently posts
pictures of their findings on his Tybee Beach Ecology Trips Facebook page.
Beach Walks
with Dr. Joe
By Dr. Joe Richardson
/(www.TybeeBeachEcology.com)