Ecological niches

They have found their own places, so many species, it boggles the mind. Lobster crawl upon the bottom, in deep or shallow waters— fifty-four species. Crab live in saltwater, freshwater, or on land—six thousand seven hundred ninety three species. Mantis shrimp hide in the sea in rocks or burrows— four hundred fifty species. Seed shrimp, ranging from minuscule to an inch or so— thirteen thousand species. Thousands other species have found their own places.