Exploring Low Tide

As you might know, I went on a road trip over my Winter Break. Much of it was spent exploring the beautiful South Carolina Lowcountry. I spent 4 days of my time in the Lowcountry camping on Hunting Island State Park on the southern tip of South Carolina.

Driftwood on the beach at Hunting Island.

This isn't the first time I've been to Hunting Island State Park; the ornithology class I was taking last semester stayed here while on a birding trip (Link). It's an absolutely amazing place that I wanted to revisit, so I decided to come back on my break. I spent most of my time birding around the area, but whenever I wasn't birding, I was exploring the island's beach. First, some background on the setting. Hunting Island is a subtropical barrier island in the Atlantic Ocean. The natural beach is approximately 4 miles long. As with elsewhere, Hunting Island experiences 3 types of tidal cycles: daily, monthly, and annual. These are all caused by different types of interactions between the Earth, Moon, and Sun. The most obvious tidal cycle is the daily cycle. This cycle is caused by the interplay between the Earth's rotation and the Moon's gravity. This results in 2 daily high tides and 2 subsequent low tides. The tides can make the beach on Hunting Island go from only 10 or 20 yards wide during high tide to 100+ yards wide during low tide. I opted to explore during low tide, as many "goodies" are visible once the intertidal zone is exposed.

Until this trip, I've never had the chance to really explore a beach. I honestly didn't know what kinds of things to expect, especially in South Carolina. I was absolutely flabbergasted to see Sea Stars. One part of the beach during low tide had some rocky tide pools, and these tide pools were teeming with dozens of sea stars and various other life. All the sea stars were one species, the Forbes Sea Star (Asterias forbesi). The Forbes Sea Star can be found in Atlantic coast intertidal zones ranging from Maine down to the Gulf of Mexico. It has a characteristic orange madreporite. The madreporite (the round orange thing near the center) is a specialized opening which all sea stars have. The madreporite is essentially a valve which allows sea water into the specialized water vascular system which run throughout the sea star's body. Sea stars actually use sea water essentially as a means of locomotion in a rather complex process. You can read more about this process and the madreporite at The Echinoblog.

The Forbes Sea Star is a molluscivore, meaning it feeds on mollusks. Specifically, the Forbes Sea Star feeds on bivalve mollusks, which are mollusks that are enclosed by two shell parts which are attached by a hinge. Bivalves include commonly-known mollusks like clams, oysters, mussels, etc. The Forbes Sea Star tracks down bivalves by honing in on the chemical "smell" of bivalves. Once it senses a bivalve, the sea star will crawl toward it. Upon reaching it, the sea star will then grab the bivalve with its tube feet (which you can see in the photo above). The sea star then uses its tube feet to pry the bivalve's shell open, exposing the helpless mollusk inside. This is when things get a little strange. Instead of "swallowing" the squishy mollusk body like you might think it would, the Forbes Sea Star does things a bit differently. It pushes its stomach out of its body and up against the body of the mollusk where it then excretes digestive enzymes that begin to break the mollusk down. The stomach then absorbs the resulting nutrients before getting pulled back into the sea star's body. Pretty crazy, isn't it?

Another common sight in the tide pools I explored was the Warty Sea Anemone, Bunodosoma cavernata. Sea anemones are actually animals in the Order Actiniaria. The sea anemones are Cnidarians (Phylum Cnidaria), and as such they are related to jellyfish, corals, tube-anemones, and the like. The Warty Sea Anemone is a more southerly species in the US, ranging from North Carolina down throughout the Caribbean. The venom of the Warty Sea Anemone isn't toxic to humans like some other sea anemone venom can be, and so they pose essentially no threat to the beach goer. If you decide to gently poke one, you can witness their reactionary defensive behavior which consists of quickly pulling its tentacles in to a tight ball.

Sand Dollars, with a live individual on the left, and a dead individual on the right.

As I moved away from the tide pools and walked along the beach, I often came across individuals of a species of Sand Dollar called Mellita isometra. Common names for this species include the Keyhole Sand Dollar and the Five-Holed Sand Dollar. Sand Dollars are actually a type of sea urchin that have a flattened body which helps them easily burrow under sand. Mellita isometra is a species which can be found in soft intertidal zones to shallow depths of ~100 meters from Massachusetts down to Florida and the Bahamas. Most of the Sand Dollars that people find along the beach are actually the "skeletons" of dead individuals, called "tests." To see the difference between a live Sand Dollar and a dead one, look at the photo above. The Sand Dollar on the left is alive; notice its purple coloration and fuzzy appearance. On the right you have the test of a dead Sand Dollar. Notice how it's smooth and a pale creamy color; it's much different looking than a live individual!

Of course, one of the most common sights on the beach are various mollusk shells. There are, however, few shells in South Carolina as large and eye-catching as the Knobbed Whelk, Busycon carica. I was wading through a shallow channel on the north end of Hunting Island when I came across my lifer Knobbed Whelk. The large shell sitting in the sand easily grabbed my attention. Amazingly, this is a small Knobbed Whelk. A full grown adult will be between 5 and 12 inches long, while this one was only about 4 inches.

So what exactly is a whelk? A whelk is essentially just a type of sea snail. More specifically, they are sea snails in the family Buccinidae (the true whelks), but some sea snails in other families have "whelk" as part of their common name (which is one of the many issues with common names). The Knobbed Whelk can be found in near-shore environments ranging from the intertidal zone to 50 or so meters deep. Their range extends from Massachusetts to northern Florida, and in South Carolina they are the most common of the whelk species present (there are 4 total in South Carolina). They are a predatory snail that feeds on bivalves such as oysters and clams.

As with all creatures, Knobbed Whelks eventually die. After their soft body decomposes, a nice empty shell is left over. That shell makes for a great hermit crab home. In fact, the hermit crab in the photo above is using a small Knobbed Whelk shell as its temporary home. Hermit crabs are a type of crustacean, but they aren't actually true crabs. Hermit crabs are kind of their own thing. Most crustaceans have a completely hard body due to it being nearly all calcified, but the hermit crabs have a non-calcified, and subsequently soft, abdomen. This soft abdomen is a very big weak spot for the hermits, and they have come up with an easy fix: crawl into an empty shell! Most often a hermit crab will choose a snail shell of some sort, like the individual above. By using this shell as a mobile protected "home," the hermit crab can better prevent becoming an easy meal for a hungry predator.

There are several species of hermit crabs in South Carolina, and I have essentially no knowledge when it comes to identifying crustaceans. I think this is a Long-Clawed Hermit Crab, Pagurus longicarpus, however I could be totally wrong. Another common species is the Thinstripe Hermit Crab, but this individual lacks the characteristic pinstripes. Another possibility is the Broad-Clawed Hermit Crab, but its claw doesn't look nearly large enough. If anyone can help me positively ID this species, please leave a comment!

Of course, if I'm going to talk about hermit crabs, I should probably talk about the true crabs! This guy was a surprise find. I was in one of the tide pools looking around when I saw something just barely sticking out of the sand. At that point in time, all I could see was the outline of a round object. I thought it might be some sort of bivalve, so I put my hand under it and attempted to pull it out of the sand for a closer look. Suddenly, the object erupted in a flurry of movement, stirring up the sand and clouding the water. I jumped, and then felt a pinch on my hand. Oops, it was a crab. The sand settled to reveal the scene above - a now-obvious blue crab sitting half buried in the sand. My colleague Alayna Tokash identified this as the Atlantic Blue Crab, Callinectes sapidus, which is often just referred to as the "Blue Crab" (although there are several species of blue crabs in the Atlantic).


The Atlantic Blue Crab is a commonly consumed crab, and is also a very economically important species for the Atlantic Coast. However, there's some trouble. The Atlantic Blue Crab population has been declining for some time. It is estimated that the population declined from 900 million individuals to approximately 300 million individuals from the mid-1990's to 2004. In the Chesapeake Bay region, where the Atlantic Blue Crab is most heavily harvested, the population is estimated to have decreased by nearly 70% over the past few decades. Overharvesting is, as you might have guessed, a major problem, but several other factors, including diseases and habitat degradation, are to blame as well. These declining trends suggest an upcoming battle between conservationists advocating for the protection of the Atlantic Blue Crab and the crabbers who rely on this species to make a living. Hopefully it doesn't get to that point, but this is a scenario that is played out much too often nowadays...

I know this is a very different subject matter than what I normally get the chance to write about, so hopefully you enjoyed it! Thanks for reading!

South Carolina, Pt. 1

As you might know, I am currently taking Ornithology (the study of birds) at Ohio University. This is one of the required classes for my Wildlife and Conservation Biology major, and also one of my most-anticipated classes of my college career. We go on weekly field labs (You can read about each one at this link), but we also get to go on two big trips. One of these trips is to Lake Erie, which is coming up in November, but the other trip was last week. As you might guess by the title, it was a trip down to South Carolina. The point of this trip was to expose us to birds we would normally never see in Ohio, and so we were doing some relatively intense birding to find all those special species. If you've ever went birding to that degree, you probably know that taking photos is pretty difficult, as you simply don't have the time for it. So sadly I don't have a bunch of photos, but I'll try to make do with the ones I did take.

We left Athens, Ohio, at 8 AM on Thursday, September 24th. Eleven hours and a slight detour later, we arrived at our destination, Hunting Island State Park. Hunting Island State Park is located in extreme southern South Carolina. The entire park is located on an island in the Atlantic Ocean. This island is one of the few remaining undeveloped barrier islands located within the so-named Sea Islands, which is a chain of tidal and barrier islands ranging from mid-South Carolina to extreme northern Florida. Hunting Island has a subtropical climate and consists of several different ecosystems. On the Eastern side of the island is the Atlantic Ocean, shown above. The Western side consists of extensive salt marsh habitat. The island itself consists mainly of maritime forest. In this part of the world, maritime forests are dominated by evergreen trees, with the majority of those trees being pine trees. In this case Loblolly Pine was the dominant tree, with Slash Pine, Southern Live Oak, and other trees mixed in. The iconic Cabbage Palm occupied the mid-story, which you can see in the photo above. Those tall pines pictured are the Loblolly Pine. The understory was occupied primarily by Saw Palmetto, Serenoa repens. An interesting and well-recognized species of fern-like palm, Saw Palmetto is restricted to the Southern Atlantic Coast and Eastern Gulf Coast. It can be found in only one county in South Carolina (Beaufort), which is where Hunting Island is located. There are other similar-looking palm species found in the understory here though as well, such as Needle Palm.

We arrived near sunset, ate in the city of Beaufort, and then headed toward the park in the dark. It had began to rain by the time we arrived, which added a whole new dimension of fun as we frantically tried setting up our tents before they got too wet inside. That rain turned into a storm with incredible lightning, Earth-shaking thunder, and torrential rain. It turns out that storm system also spawned an EF-2 tornado in Johns Island, which was only a mere 35 miles away from us. Thankfully we just received heavy downpours; a tornado might have put a slight damper on the trip, to say the least.

When morning came, the rain had stopped but the skies were still pretty overcast. We ventured out to the beach to look for shorebirds and other related birds. Laughing Gulls, Brown Pelicans, and various terns quickly greeted us. A few shorebirds were out and about, including a Ruddy Turnstone, multiple Willets, and some peeps we couldn't identify. A lagoon on the other side of the dunes held a Bald Eagle, Osprey, Little Blue Herons, Great Egrets, Great Blue Herons, and Snowy Egrets. Many warbler species flitted about the trees, and Brown-Headed Nuthatches squeaked like a dog toy from the canopy.

After a few hours, we moved to the Western side of the island. This side of the island has an extensive salt marsh. A salt marsh is essentially the area between open salt water and dry land. This area gets routinely flooded with salt water every day due to the tides, which in turn creates a soggy and salty salt marsh. I took this photo during low tide, and you can see how the salt water is restricted to a shallow river (named Johnson Creek). Once the high tide comes in, the water level will rise (in the case of the day this was taken, it rose 7 feet), and most of the Smooth Cordgrass, Spartina alterniflora, that you see will be nearly covered.

The saltmarsh produced more herons, including our first Tricolored Heron of the day. Four Wood Storks, a federally-listed Endangered Species, flew over us, drawing ooh's from the class. Several Willets, a species of sandpiper, foraged along the exposed mud bank of Johnson Creek. For several minutes, a Clapper Rail ventured out into the open along the bank to forage next to a sleeping Laughing Gull. To our surprise, a dolphin also made an appearance. Due to the location, I'm nearly certain that it was a Common Bottlenose Dolphin, Tursiops truncatus. There are other species of dolphin near South Carolina, but most of these are more open-ocean species. The Common Bottlenose Dolphin is the only species which commonly swims to the shore, into lagoons and marshes, and up estuaries. It was amazing to see one so close!

We then went to Paradise Pier, a 1,120 foot pier that juts out into Fripp Inlet. Here we had 30+ Brown Pelicans, dozens of Laughing Gulls, 2 Herring Gulls, another Bald Eagle, more heron species, and the birds on the sandbar in the photo above. This sandbar, which was just off the pier, was a very productive piece of land. About 20 Sanderlings (a species of sandpiper) and 3 Willets foraged by the water's edge. A group of terns flew in a few minutes later. There were Caspian, Royal, and Sandwich Terns in the group. Then the most exciting species of the pier flew in: 3 Black Skimmers (the black birds on the center-left). We also got to see two cool fish species. One fisherman pulled up a large Red Drum, Sciaenops ocellatus, which was probably around 2 and a half feet long. Another caught one of the Dasyatis stingray species, which was incredible to see in the wild! I'm not sure of the exact species, but it was either the Atlantic, Bluntnose, or Roughtail Stingray.

One of the best parts of this trip was seeing so many new things that I've wanted to see for years. I haven't been near the ocean since I was 4, and so I was looking at everything around me with new eyes. Every other bird I looked at was essentially a lifer. Every plant I looked at was a species I had never seen before. Plants I had learned about in class, like the Loblolly Pine, finally came to life in front of my eyes. I'm a bird guy first and foremost, so the birds were obviously the stars of the trip, but this spider was definitely one of the stand-out highlights. This is the Golden Silk Orbweaver (more commonly known as the Banana Spider), Nephila clavipes, a species of spider I have wanted to see for years and years. When you're into biology, you'll often find yourself doing things that the average person would not do. For example, I was walking to the bathrooms the first morning when I ran face first into a huge, very strong orbweaver web. The web was larger and stronger than any I had seen before. Now, the average person would have freaked out and tried to get away as fast as possible. The first thing that jumped to my mind though was "OH MY GOSH, CAN IT BE A BANANA SPIDER?!?" I looked up to my left to see the massive palm-sized spider frantically running away from me. It was! My lifer Banana Spider! I was ecstatic and quickly went to get an even closer look. This is an absolutely beautiful species. Although big and "frightening" looking to some, these are really harmless spiders that won't do anything unless you handle them roughly.

Fiddler crabs, Uca sp.

We ended the day a little before sundown. Our awesome TA Brandan Gray made everyone jambalaya, and we had a wonderful (and much-needed) dinner as the sun set through the pines at our campsite. A little bit later, the class decided to head off to the beach. Due to Loggerhead Turtles nesting on the beach, lights of any sort are banned for the Summer until the end of October, but there was a nearly full moon out which lit up the beach. It was nearing low tide, so a large portion of the beach was exposed. As we walked along the beach, Brandan yelled out "Dolphin!" and pointed to a blob swimming about 30 feet from shore. We looked out and I noticed the creature had a heterocercal tail. That meant one thing. I yelled out "THAT'S A SHARK!" and sure enough it was. It was the first time I ever saw a shark out in the wild, and I was beyond ecstatic. I have no idea what species it was, but it was about a 5 foot long individual who was slowly swimming parallel to the shore about 30 feet out. We followed it down the shore until it disappeared back into the ocean, marking the end of an amazing day.

Since it would be too long to list out all the species here, you can see my bird checklists for the day at the following links:

1. Hunting Island SP Forest, Lagoon, and Beach
2. Hunting Island Salt Marsh
3. Paradise Pier (Hunting Island SP)

I should have Part 2 up by tomorrow, so stay tuned! Part 2 can be found right here!