5. Horseshoe crab babies look just like adults — but with translucent shells.
It takes two to four weeks for horseshoe crab eggs to hatch. Tiny crabs emerge, smaller than the eraser on a No. 2 pencil and with nearly see-through shells. The baby horseshoe crabs find shallow, sheltered waters to live in. They molt several times in their first year, shedding their old shells to reveal new shells underneath. Their shells darken as they age. The crabs continue to molt, but with less frequency, as they grow older.
6. Many shorebirds can’t survive without horseshoe crabs.
Thousands of shorebirds descend on Delaware Bay in May to feast on horseshoe crab eggs. Red knots, ruddy turnstones and sanderlings and other species rely on the fat- and protein-packed eggs to power their long flights. For red knots, this important stopover is the last chance to fuel up before the final leg of an epic 9,300-mile migration from South America to the Arctic.
But fishers use horseshoe crabs as bait to catch eels and whelk (sea snails), and crab populations are getting smaller. In some states, it’s illegal to catch horseshoe crabs. If harvests continue, the crabs could disappear — along with the shorebirds that rely on them.