Our state's Natural Science Museum has a pair of them in a several thousand gallon tank. They are sure interesting creatures.

 

They need a large tank for more than their size! They eat micro fauna and detrius off of and out of the sand bed. These are quickly depleted and need time to be replaced. In most tanks, the horseshoe will die in a few months out of starvation. I didn't know they were endangered though! I've even seen them for sale around here!

 

I didn't know they were endangered though! I've even seen them for sale around here!

I think they are only a protected species in New Jersey (which is where I live) so I am probably wrong about them being endangered. I do know that they are popular bait fish, so they are caught with some frequency along more southern coasts.

I felt bad for this one, though. It had lost its tail. There was a storm out to sea the night before I found it, so I don't really know if it was a recent injury or not. I hope it survives.

 

I've been to two different aquariums where they keep them in "touch tanks", these sprawling but shallow tanks where you can reach in and pet them. They do look creepy underneath, haha

 

Horseshoe crabs are amazing creatures, in so many ways, the blood they harvest from them does so much for mankind, a creature that has been around for 250 million years with little change has to be amazing, what's even crazier is that there not really a crab, they more related to the spider and scorpion family, there one creature we can't afford to fish to extinction, there to important to this planet in so many ways.

 

My dads 65 gallon tank has 2 horseshoe crabs, they can fit in the palm of your hands, I see them once in a while scurrying around the tank floor, but most of the times they stay burrowed in the sand.