In a laboratory at the Smithsonian Environmental Research Center in Edgewater, Maryland, zoologist Rob Aguilar examines bottles containing preserved specimens of an astonishing array of different varieties of aquatic life.“We have speckled swimming crabs, long finned squid, jackknife clam, ponderous arc,” said Aguilar, scrutinizing a thick mussel with a serrated shell. “This is a fish-gill isopod. And this is a big marine leach that prefers to be on skates and rays.”