Shore Buddies Wisdom Wednesday
Image by Kristofer Landers
The horseshoe crab is a living fossil. It has been on Earth some 220 million years, longer than dinosaurs. And it survives today almost identical to its ancient ancestors. Horseshoe crabs are more closely related to spiders, ticks and scorpions than they are to true crabs. Their body is divided into three sections, the first of which contains their mouth, a pair of feeding pincers and five pairs of legs. Their second body section is their abdomen, and it contains five sets of book gills -- flap-like structures that allow the horseshoe crab to breath under water. Because their exoskeleton doesn't grow with them, they must shed, or molt, in order to grow. They may molt 16 to 17 times before they reach their adult size. After this, adults rarely molt. The third section is their tail spike which is used to steer and to right themselves if they get turned upside down while swimming. Most horseshoe crabs spend most of the year in deep water. Every spring, they migrate to the shallows, emerging from the sea to mate along the beaches on moonlit nights, when the tide is high. Females can lay 90,000 or more eggs per season.