Monday, April 23, 2018

Critter Tale: The Atlantic Horseshoe Crab—Not Really a Crab.

by Rachael Lewin, communications intern

Hello! I am one of the horseshoe crabs living at the Save The Bay Exploration Center and Aquarium. I don’t have an official name at the aquarium, but you can call me "Poly"—short for Limulus polyphemus, the scientific name for my species. Save The Bay’s education team found me in Narragansett Bay a few years ago. Right now, I live in a touch tank with other horseshoe crabs, little skates and moon snails. As with many other critters at the aquarium, the team brought me here at a young age with the intention of keeping me safe until I’m fully grown and able to scour for food on the ocean floor and defend myself from local predators and then releasing me back into the wild. Just about everyone has seen a horseshoe crab shell washed up on a beach somewhere. After all, we've existed on this planet for millions of years. But, we’re still really misunderstood and I'd love to clarify a few things for you.

At first glance, everyone thinks I am a baby, but I’m just smaller than all the other adult horseshoe crabs here. Usually, the way horseshoe crabs grow is by shedding our old small shells so a new, larger one can grow in its place, a process called "molting." While our new shells develop, we must be extra careful to avoid predators such as sharks, turtles and seagulls, because the new shell takes a few days to harden. Save The Bay’s aquarist, Adam Kovarsky, says they’re not sure why yet, but my shell seems to grow at a slower rate than the average horseshoe crab, which lowers my chance of surviving in the wild. So, as it turns out, I’ll stick around for a while. 

My size isn’t the only misperception people have about me and my horseshoe crab brothers and sisters. When I crawl out from my resting place under the cool sand to say hello, visitors often are afraid to touch me when they see my claws, squirmy legs and spiky tail moving all around. But, from our name to our spiny bodies, we are much gentler than we appear on the surface.

My tail, a long spike that drags behind when I move, is not used for stinging people and other critters, as many think. When we get flipped upside-down, we use our tails to turn us back over onto our feet. We also use our tails to help us steer as we move along the bottom of the ocean, much like a rudder on a boat.

Did you know that horseshoe crabs are not actual crabs? We’re more closely related to ticks, spiders and scorpions. We got our name because of the five sets of legs underneath our shell. Our legs have pincers on the ends that look a lot like crab claws, but are much too soft to do any damage to humans. We use our claws to tear apart food and place it into our mouth, in the middle of our underbelly. Also, our claws help humans identify our gender. Males have claws that are round and shaped sort of like boxing gloves, and females have longer thinner claws that, when open, look like two fingers making a peace sign. Look at the picture to the right: by looking at my first set of legs, can you tell if I am a girl or a boy?

Horseshoe crabs are often referred to as “living fossils” because we’ve been around for longer than any other animal in the world—over 300 million years—and our bodies have not changed! We have a vital presence in marine ecosystems; our eggs provide food for shorebirds, and sometimes our shell serves as a home for various creatures looking to hitch a ride. We also serve a very important purpose for humans. In the ’50s, a scientist discovered that our baby-blue blood contains a special cell that prevents bacteria from invading our bodies. Since then, our blood’s been harvested for use in the development of pharmaceutical drugs and vaccinations. Because we are so important to the medical community, scientists go to great lengths to minimize the fatality rate of horseshoe crabs being used in the process, yet about 10-30 percent of us still die during or after the process. When the reality being harvested by humans is combined with the threat of natural predators, life in the wild is even riskier for little guys like myself, making my current home at the Exploration Center and Aquarium so important to me and many other marine creatures.

I am so happy I was rescued and brought to Save The Bay’s Aquarium and Exploration Center because I’m safe and serve an important purpose as an educator. I love my current tank-mates, but I’m always excited to see what new critters will come in to hang with us! Come see me and all of my friends at Save The Bay’s Exploration Center and Aquarium located at Easton’s Beach in Newport! We're open from 10 a.m. to 4 p.m. every Friday, Saturday and Sunday until Memorial Day. During summer, we're open every day! Hope to see you soon!

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