How did horseshoe crabs get their names? Are they even crabs? And did they really exist before the dinosaurs? Early spring presents a unique opportunity to see these living fossils up close as they scuttle up to the shoreline along the Atlantic coast of the United States to mate and spawn. But Why traveled to Cape Cod to see horseshoe crabs up close. There we met up with horseshoe crab expert Sara Grady, who works for Mass Audubon. We learn all about these arthropods and answer questions like: Can humans eat horseshoe crabs? What’s with the pointy tails? Do they pinch? How long do they live? And what’s so special about their blood?
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- These animals are considered living fossils because they’ve been around for about 450 million years, and are largely the same today.
- They are not crabs! These arthropods are more closely related to scorpions and spiders than to true crabs.
- Horseshoe crabs get part of their name from the armored U shape of their bodies. In addition to that large U-shaped carapace, they have a smaller middle abdomen section, and a long pointy tail.
- Underneath their shell, they have 5 sets of legs, and one pair of feeding pinchers that help them get food into their mouths. Horseshoe crabs eat worms, small shellfish and small shrimp-like animals that live in the mud.
- . Horseshoe crabs have a total of 10 eyes!
- Horseshoe crabs do not pinch, but they will fold if you pick them up and so you can pinch your fingers in between the two parts of their shell.
- The long pointy tail may look threatening, but it doesn’t have venom or a stinger. They use their tail to flip themselves over if they get tumbled and go belly up.
- Horseshoe crabs come up on shore to spawn during high tides. They’re especially abundant during the full and new moons in May and June, when the tides are higher than normal.
- They come up to the shore because that’s where the female lays her eggs. The eggs have less chance of getting washed away if they’re just above the tide mark.
- Females can lay 80,000-100,000 eggs per year. Males fertilize the eggs after the female deposits them in the sand. Then the eggs get covered up.
- The eggs take two weeks to four weeks to hatch, and then the miniature crabs will make their way into the water during high tide. Baby horseshoe crabs look like tiny adults, but they’re tailless. (Spiked tails and egg shells don’t mix very well!)
- Humans do not eat horseshoe crabs (though there’s a market for their eggs), but we do harvest them. They are used as bait for whelk fishing, and their blood is used in some biomedical applications.
