Animals on Tybee’s beach
A Few of the “What is this?”
Because of Tybee Island’s location between Cape Hatteras, NC, and Cape Canaveral, FL, we are in an overlap or transition zone between cool-water and tropical coastal marine faunas and floras. So we get to see plants and animals from both areas. Tybee is also surrounded by a variety of coastal marine habitats including salt marshes, estuaries, soft sandy bottom areas, and offshore hard-bottom reefs. So when you add all these features to our wide intertidal zone along the beach, it’s no wonder that I’m often heard saying, “you never know what you will see on Tybee’s beach!”
During our Tybee Beach Ecology Trips, we generally find quite a variety of different animals, and the discoveries are often different from one day to the next. As we finish a trip, I’ll usually ask folks that if they come across something on the beach that they don’t recognize to please get a picture and email or text it to me, or post it on the facebook page, and ask “what is this?” I love getting “what is this?” messages! So here are a few of the interesting animals that I frequently get asked about, and that you might encounter out on Tybee’s beach.
The Sea Pansy is actually a type of soft coral. It’s a round, flat, purple disk with a pink stalk. They live in shallow, sandy-bottom areas where the stalk sticks down in the sand to anchor the flat disk on the surface of the sandy bottom. Imbedded in the top of the disk are dozens of tiny polyps that look like tiny anemones, each with 8 tentacles. Underwater, these polyps extend out of the disk, and the tentacles catch microscopic plankton for food. Because all the polyps are connected to each other, a Sea Pansy is a good example of a “colonial” animal that is like one individual composed of many smaller individuals connected to, and supporting each other.
A Sea Whip is another colonial, soft coral, and are closely related to Sea Pansies although they don’t look anything alike. A Sea Whip looks more like a plant or tree branch. Most commonly they are yellow or purple, but you might come across a white or orange one. If you look closely, you can see the tiny holes or slits all along the branches; and it is down inside those holes where the polyps are. Like the Sea Pansy, when underwater, the polyps stick out and the Sea Whip will look fuzzy because of all the tiny white polyps and their tentacles. Unlike the Sea Pansy, a Sea Whip will grow attached to a hard bottom or structure.
Maybe one of the strangest colonial animals I get asked about is Sea Pork. Usually when you find a clump of it on the beach, it would have washed up from offshore. They grow attached to hard bottoms and reefs offshore, but sometimes get knocked off and washed ashore. They are actually a colony of small sea squirts or ascidians, and they can come in a variety of colors ranging from bright red, blue, green, gray, beige and white. They are tough, rubbery feeling, and every one of them is a different shape and size.
The Mantis Shrimp is one of those things that I don’t handle with my own hands. Usually I’ll use a net or shovel because its praying-mantis-like pair of pinchers are very strong. They not only can pinch with them, but they can also flick them out with great speed and force, and can actually spear prey with them. A Mantis Shrimp is quite an acrobat and fun to watch in a pan or bucket of sea water because they can swim rapidly but can fold and roll up and do flips. Mantis Shrimp dig into the soft sandy/muddy bottom and make burrows and then come out to hunt.
Soda Straw Worm tubes
Have ever seen what look like strips of paper a few inches long laying on the sand? These are probably the paper-like tubes from Soda Straw Worms. These worms live in the shallow sandy bottom usually just beyond the low tide line where they burrow vertically down into the sand. Their skin produces a lot of slime that becomes a paper-like lining for their burrow. So they produce this paper straw like tube; and the worm can move up and down inside of it, and the sand doesn’t cave in. Usually the very top of the tube will stick up above the surface of the sand by about a quarter or half an inch. As the sand shifts due to our tides and waves, the old tubes get washed out of the sand and wash up on the beach. So what we often see are the collapsed tubes that look like strips of paper.
Let’s take the sand-dwelling worm story one more step. Another species of tube building worms is the Plumed Worm, so called because its gills look like feathers or gills. A Plumed Worm will also secrete at smooth paper-like tube to line its hole or burrow in the sand. But the Plumed Worm takes it a step further. It will catch and gather bits of seaweed, shells, marsh grass, even trash, out of the water drifting by; and it will attach these things onto the outside of its tube. It will reinforce the top few inches of its tube with these things. So when a piece of an old Plumed Worm tube washes out of the bottom and up onto shore, it often looks like a short chain or string of shells – sort of like a mermaid’s necklace!
These are just a small sample of the variety of marine animals you might find along Tybee’s beach. So if you find something you don’t recognize, feel free to take a picture and email to me or post it directly on the Tybee Beach Ecology Trips facebook page, and ask “what is this?” I’ll be glad to give you a not-so-short answer!
Dr. Joe Richardson is a retired marine science professor who has studied, researched and taught marine biology/science along Georgia’s coast and Bahamas for more than 35 years. Dr. Joe also conducts Tybee Beach Ecology Trips (www.TybeeBeachEcology.com) year-round for families, schools, scouts, and other groups. He regularly reports his findings on his “Tybee Beach Ecology Trips” facebook page. And for more information and pictures about Tybee’s marine biogeography and seasonality, see his webpage: www.ceasurf.com/pages/TybeeDiversity.aspx