sentences:  Their predators include sea otters, starfish, wolf eels, triggerfish, and humans.Like other echinoderms, urchins have fivefold symmetry as adults, but their pluteus larvae have bilateral (mirror) symmetry, indicating that they belong to the Bilateria, the large group of animal phyla that includes chordates, arthropods, annelids and molluscs.They are widely distributed across all the oceans, all climates from tropical to polar, and inhabit marine benthic (sea bed) habitats from rocky shores to hadal zone depths.