. >> reporter: lisa ferguson the director of research and conservation at new jersey's wetlands institutethe crabs spend most of their lives deep under water, they surface in late spring and early summer to delay their eggs. >> so they're depositing eggs into the sand. she has some males that are coming along with her. >> reporter: an estimated 40 million horseshoe crabs live in the bay, although they can be found all along the atlantic coast. >> horseshoe crabs have been around over 450 million years. >> reporter: further up the beach tony works with the american littoral society so there is that sweet spot right here. >> reporter: teaching volunteers how to tag select crabs for tracking. frequently described as living fossils, these resilient, bizarre-looking armored creatures have survived numerous mass extinction events. >> they are arthropods and that's why they are closely related to scorpions and spiders and they are not crabs. >> reporter: horseshoe crab not a crab? >> horseshoe crab not a crab. >> reporter: not a horse either. >> yeah. >> reporter: a female can lay 4,000 eggs a n

. >> reporter: lisa ferguson the director of research and conservation at the wetlands institute.ir eggs. >> they are depositing eggs into the sand. she has males that are coming along with her. >> reporter: an estimated 40 million horseshoe crabs live in the bay, although they can be found all along the atlantic coast. >> horseshoe crabs have been around over 450 million years. >> reporter: further up the beach tony works with the american littoral society teaching vol terse tiers how to tag select crabs for tagging. described as living fossils, these bizarre creatures survived numerous mass extinction events. >> they are arthropods and that's why they are closely related to scorpions and spiders and they are not crabs. >> reporter: horseshoe crab not a crab? >> horseshoe crab not a crab. >> reporter: not a horse either. >> yeah. >> reporter: a female can play four eggs a night. >> you can see the eggs that washed up and come to the surface. >> reporter: they are tiny. but only the ones that stay buried in the sand have a chance of hatching. when the tide turns into a feeding fre