There’s a lot more to a horseshoe crab than meets the eye. They are not even crabs and are actually more closely related to spiders and scorpions. They don’t have teeth or jaws, and they’re not venomous. Their tails might look scary, but they are used to help turn the crab back over if it gets flipped upside down while on the beach.

Horseshoe crab blood is used to help test medicines and their eggs are an important food source for birds.

Watch more about the seven-legged, ten-eyed invertebrate in NOAA Ocean Today's collection of videos.