Ключевые слова: animal, aquatic, behavior, cluster, colorful, creatures, echinoderms, ecosystem, environment, floating, group, invertebrates, marine, marine biology, movement, nature, ocean, ocean animals, ocean floor, ocean inhabitants, oceanic, prickles, prickly, round, saltwater, sea, sea bed, sea bottom, sea urchins, shallow, spiny, tropical, undersea, underwater, water, water surface, wildlife,