Seaside Stroll

A stroll down the beach on a warm fall day.

Though most of the tourists are gone, there are a few fishing and crabbing along with the locals. Every time we’ve been to Breach Inlet lately, there has been a juvenile Brown Pelican begging at the feet of the fishermen and families crabbing.

While it seems harmless, even helpful, to toss this beggar a few scraps of bait, or even a bait ball [which he steals now], this fellow is wasting his invaluable learning year on being hand fed.  Pelicans have a specialized method of feeding that isn’t inborn, they have to learn it over time. Adults have a higher feeding success rate than juveniles, suggesting not only that juveniles need time to perfect their technique, but that it’s also harder for juveniles to get the required caloric intake. So are you REALLY helping wildlife when you give handouts?

Anyway. Moving on…beaches are the best for looking at invertebrates. A neat pair we found on our stroll was a Grey Sea Star and a Long-wristed Hermit Crab in a tide pool.

The Sea Star seems to have had a rough time holding on to his arms. The Grey Sea Stars don’t have suction cups on their tube feet like other sea stars do, but instead they use their tube feet to dig in the sand for clams.

Here is a good view of the underside and the tube feet. I’m not sure what is protruding out of his belly, but sea stars only have a mouth, so anything that goes in and can’t be digested is regurgitated back out…lovely thought, eh?

Though not whole nor alive, this was still a neat find: a Calico Box Crab!

Much more lively was this Speckled Crab. His camouflage is pretty good, but he’s much better at burying himself until only his eye stalks are showing! Works well to hide from gulls and fish, but doesn’t do much good in avoiding being stepped on.

By far the best find while on the stroll was this fellow:

A Ghost Shrimp! They are responsible for the plethora of holes you find on the beaches here in the Lowcountry, though they almost never come out of them. In fact, a researcher working with these guys said they would die within three hours of being excavated out of their burrows, though they were adequately accommodated. This individual is probably Callianassa major since it was so large! It seemed really disoriented, but eagerly went down the burrow once I put his head in it.

Every now and then you’ll see a curious person try to dig out and discover what makes all the little holes. Unfortunately for them, the burrows of ghost shrimp can go down 6 feet, and they are fast, so finding one is pretty tough. A really awesome and rare find for us, I am sure it was terrifying for the shrimp.  Though called a shrimp, this fellow cannot swim and is more closely related to another non-swimmer, the hermit crab, instead of its namesake cousin the swimming shrimp. The exoskeleton isn’t hard by any standards and though most ghost shrimp have one large claw, it won’t provide much defense.

That find topped off our Seaside Stroll. Hope you enjoyed!

Holes on the Beach

Do you remember when you were a little kid and you maybe loved digging holes at the beach? Perhaps you tried to excavate tunnels or you simply dug a hole in which to bury your feet. What we do to entertain ourselves, animals do for survival.

“What makes all these holes on the beach?”

Within the first week of moving here, my husband and I took a stroll on the beach near Fort Moultrie.  Being January, there weren’t many people walking around, aside from an elderly midwestern couple that was headed towards us.  The fellow stopped when he was withing speaking distance, leaned heavily on his cane, and stated: “You two look like beachwalkers. What makes all these holes?” Still confused as to what of my appearance suggested beachwalker [I had hiking boots on!], I fumbled around for a logical answer. I really had no idea since we had just moved here, but I threw out ‘worms’ as a possibility, to which the gentleman countered “But there’s so many!”

While there are beach worms that make holes, like the lung worm, there is also another hole-loving character–the ghost shrimp.

Ghost shrimp, as well as other shrimp, crabs, and lobsters are crustaceans with ten legs, called decapods. While the ghost shrimp sounds like it would be related to the shrimp you find on your seafood plate, it’s actually more closely related to the American lobster and hermit crabs. They have long bodies, a fanned tail, and usually one claw is extraordinarily larger than the other, white in color, and very smooth, as seen in the photos.

These ‘shrimp’ dig extensive passages under the sand, going as deep as 6 feet below the sand, and pump water through the burrows with their bodies. The water can come out so forcibly it looks like a miniature Old Faithful spewing [see photo right].  Other times, small bits of shells and sand will flow out.  These burrow systems are found near the low tide line, occasionally with fecal pellets deposited outside. It is said that these burrowing crustaceans love their homes so much that they can only survive a few hours without feeling their burrow walls.  Other holes found in the same area with mounds of sand or mud around them are generally worms. 

“Precise Little Holes”

There seems to be a phenomenon on the beach where thousands of beach-goers find perfect little holes in shells but don’t know how they got there.  These holes are generally found on the back-end of bivalves [things like clams, scallops, and the like], but can be found on other gastropods as well. They look like they were drilled there by someone looking to make necklaces out of the shells, but in fact, they were created by another mollusk.

Some sea snails, and in this particular case, the Atlantic moon snail, Polinices duplicatus, also known commonly as Shark’s eye, are carnivorous and actively pursue prey.  They use their very large mantle and foot to encase their food and with their radula bore a beveled hole into shells. A radula in this case is a tongue-like apparatus with many sharp teeth-like projections used to, essentially, lick holes in things.  It isn’t clear if the moon snails suck the prey out of this hole that it creates, or if perhaps because of the positioning of the hole, the abductor muscle of the bivalve releases and allows the shell to open, or maybe due to the acid in the radula, liquification of the bivalve’s muscles occurs. Whatever the case, the snail is a very efficient predator and its handiwork is spread along the beaches of the lowcountry.

Besides the child-dug holes often found scattered across busy summer beaches, there are many other holes that open up to fascinating, under the waves, drama.  Check them out and see what you find!

All photos are taken by the author. The larger versions may be viewed by clicking on them. 

Species information adapted from Seashore Animals of the Southeast.