TYBEE BEACHCOMBER | APR 2019 23
TYBEE’S ANEMONES
If you explore around Tybee’s rock jetties, you will probably see some dark brown, roundish
blobs attached to the rocks among the oysters. Usually they are protected back in the crevices
and cracks. It might surprise you to learn that those soft, brown blobs are one of the types of Sea
Anemones that we find on Tybee.
Anemones have a simple body structure. It is like a cup, with its base/bottom attached to
something hard (rock or shell) and with its mouth/opening at top. The opening is surrounded
by tentacles. Anemones use their tentacles to capture food and pull it into its mouth. Digestion
occurs down inside the cup, within the gastrovascular cavity. With only one opening, Anemones
have an incomplete digestive system. An Anemone can regulate the amount of water in the
cavity, so its body size can range from short to long. It can also shorten its tentacles, withdraw
them inward, and close its opening, to help from drying out during low tide.
Those dark brown ones on the rock jetties are Warty Sea Anemones. They are named Warty
because of blotches on their sides. They live strongly attached to rocks back in the crevices,
cracks, and hanging on the underside of rocks in the mid and low intertidal zone. During low
tide it looks like a dark brown, wet blob because it has its tentacles withdrawn to help keep from
drying out. If attached to the underside of a rock, it might be extended and hanging down a few
inches, as if stretching downward trying to reach a tide pool below. If it’s underwater in a tide
pool, its tentacles will be extended, and it will look like an anemone is supposed to look. If you
can reach it, gently put your finger on its tentacles and feel how they will stick to you. It doesn’t
sting. It is soft, with no protection, so if you touch it, do it gently.
Also on the rock jetties, there is a very small, inconspicuous anemone named the Orangestriped
Anemone. They are tiny, bright green anemones attached to Oyster shells in the mid
intertidal zone. They are easily overlooked because they are so small. When the tide is out and
they are exposed, they will be closed up and look like small splatters of lime jello scattered on
oyster shells. But when submerged, they will open up and spread their green tentacles.
A third type of Anemone we find on Tybee is the Tri-color Anemone (sometimes called Hermit
Crab Anemone). They usually have broad vertical bands of beige and brown along their side,
but their mouth is usually very bright orange or pink. They like to attach to shells being used
by Hermit Crabs. But they will also attach to objects drifting around in the water (Rubbery
Bryozoans, Whelk egg cases, even plastic trash). On Tybee, they will be found washed ashore
on the wet sand, and will probably look like a brown/beige lump attached to something else. If
you find one, put it in some seawater and usually within a few minutes it will open up, spread its
tentacles, and you can see its colorful mouth.
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)