A Walk On The Beach…

Writing and beach item photography by Judy Drew Fairchild

Walking along a Lowcountry beach is an exercise in beauty – sun glinting off the water; the ebb and flow of waves on the shore; pelicans gliding just above the ocean’s surface. But if you look a little closer (and down!), you will find shells and other signs of the many animals that live, hunt, burrow and reproduce in this remarkable shoreline ecosystem. Most animals that call this environment home can be divided into a few basic categories. See how many you can find on your next walk!

SNAILS

A large variety of snails can be found on Lowcountry beaches. Snails are univalves, which means they are one-shelled mollusks. For the most part, these are carnivorous animals that have a strong foot used to propel them through the sand. Sometimes you can find trails that lead to a live snail under the surface of the sand! Most snails have an operculum, which helps to seal the shell opening and protect the animal from predators.

Lettered olive snail shells became the state shell of South Carolina in 1984 and were given their name because the markings on them can resemble calligraphy letters. They are predatory sea snails that use their long foot to grab prey, such as coquina clams and mole crabs. Lettered olive snails live under the sand in shallow water and can grow to be 2.5 inches long. They live completely outside of their shell and do not have an operculum to close off the shell opening.

Moon snails plow through the soft sands of the swash zone. The front part of the foot is used for digging, and the mantle surrounds the shell to streamline its shape and allow the snail to move through the sand below the surface. These mollusks have a radula, a sort of toothy-tongue apparatus, which can be used to bore a hole into the shell of its prey. When you see shells on the beach with perfect holes in them, they were probably moon snail meals!

Some of the largest snails that live on Lowcountry beaches are whelks. When alive, these animals can be found just at or below the surface of the sand in tide pools. They also cruise the inter-tidal zone and shallow water looking for food. Whelks are predatory snails that uses the sharp

side of their shells to pry apart bivalves, such as clams and oysters, and scrape out the meat with a tongue-like radula.

Channeled whelk shells have a smoother exterior than knobbed whelks, and they have hard edges in the channels of the shell. They are also wider, rounder and lack the large protruding knobs found on the knobbed whelk shell.

Both knobbed whelks and lightning whelks have knobby shells, but they open in different directions if you are looking at the hole. Knobbed whelks open on the right and lightning whelks open to the left. Knobbed whelks are more numerous in the Lowcountry.

BIVALVES

Mollusks with two-sided shells are bivalves. The shells are most commonly found as single halves along the beaches, although occasionally you can find them with both sides still attached – and sometimes still alive!

Perhaps the smallest and most colorful bivalve is the coquina clam, which is often found in the wash zone of the wave. These tiny animals are a great source of food for moon snails, shorebirds and ghost crabs, and their presence is an indicator of a healthy beach. Occasionally a large group of them will become stranded in a tide pool, which creates a natural work of art.

On the other side of the size spectrum for bivalves on South Carolina beaches are Atlantic cockles, which can grow up to 4.5 inches long. Living cockles are often found at the edge of tide pools with their hinges pointed downward, which allows their foot to anchor them into the sand. Cockles are filter feeders, drawing water in to get nutrients, then puffing it out.

EGG CASINGS         

Some of the more curious items found along Lowcountry beaches are excellent signs of a dynamic and continuing ecosystem! Snails and other animals create beautiful and unusual casings to protect their young as they grow and prepare to hatch.

Whelks make long strings of egg casings that can be more than 150 capsules long, with each capsule holding about 35 eggs. The first few chambers are often empty and used to anchor the string into the sand. As they grow and prepare to hatch, the tiny whelks feed on each other, and sometimes you can find the shells of weaker siblings in stranded egg cases!

Most of the whelk egg strings found on the beach have holes in each capsule where the baby mollusks have eaten their way out.

Channeled whelk egg casings have a single hard edge, while lightning and knobbed whelk casings are squared off with more decorative edges.

Moon snails create an elaborate, round “collar” cemented together with sand and mucus on which to lay their eggs. If you’re fortunate enough to find a moon snail sand collar with eggs still attached, you might be able to see holes in the eggs where the young snails hatched or even actual tiny snails. If you do, be sure to put it back in the water to give the babies a chance!

Clearnose skates are non-boney fish that resemble (and are related to) sting rays. Female skates may lay more than 65 eggs in a season, each of which are protected in a sturdy keratin (like our fingernails) casing that resembles a black pouch with horns. The “horns” on each corner of an egg casing act as anchors that catch on seaweed and other objects to help keep it at the bottom of the ocean until the baby is ready to emerge. Also known as mermaid’s purses, clearnose skate egg casings wash up on the beach after the juvenile skate hatches.

FIVE-SIDED CREATURES

When you think of something with five-sided symmetry on the beach, it is likely to be a sea star, which are relatively common at low tide on South Carolina beaches. Sea stars feed on mussels, clams and other invertebrates and can apply up to 12 pounds of force to pry open the shells of its prey. On its underside, there is a mouth in the center, as well as many tiny tubular feet filled with sea water that help with locomotion and feeding.

The two kinds of sea stars you’re most likely to see in the Lowcountry are the common sea star (most often seen in winter but around all year), which is red, brown and purple with an orange spot above one armpit and the gray sea star.

Keyhole urchins (sand dollars) also have five-sided symmetry and are relatives of sea stars. Live key- hole urchins prowl just below the surface of the sand, using their tiny brown spines for locomotion. They pick up food particles and crush them with a mouth that is structured with five bird-shaped jaws. When alive, these animals have a velvety tan, brown or gray skin. Once the urchin dies and decomposes, its shell, called a “test,” is bleached by the sun to the off-white color most associated with sand dollars.

Be sure to “collect” shells with photos rather than removing them from the beach, especially if they are alive. And please don’t pick up live animals if your hands have sunscreen or bug repellent on them.

Judy Drew Fairchild is a South Carolina Master Naturalist and real estate professional with Dunes Properties. She lives and works on Dewees Island, where she learns something new every time she steps out on the beach.


WHAT’S IN THERE?

Something must live in the holes you pass as you walk down the beach, but what?

One of the most common inhabitants is the ghost shrimp, which lives 3-5 feet under the sand. Their holes are often surrounded by castings (fecal pellets) that resemble ice cream sprinkles. Ghost shrimp are crustaceans with long bodies and two claws, one much larger than the other. While they are called shrimp, these animals, which can grow up to 4 inches long, are more closely related to lobsters and hermit crabs than shrimp. Ghost shrimp feed on organic matter, including phytoplankton, that they filter from sea water.

Another mysterious hole dweller is the lugworm. Lugworm castings are longer and more continuous than those of ghost shrimp, but they can be prevalent on the beach, and the remains of their burrows are often visible. Lugworms are divided into three segments, with the back one closest to the surface. If the worm is in danger of something on the surface bothering it, the entire rear end can be cast off and regenerated. Lugworms play an important part in maintaining the marine soil. Much like earthworms in a garden, they re-oxygenate the sand around them and constitute 30 percent of the biomass on an average beach!

 

2018-10-19T10:16:32+00:00