Sharks are cartilaginous fish with about 400 species. Whale shark is the largest species, reaching up to 65 feet. Basking sharks are second-largest, reaching up to 40 feet
Lionfish has venomous fin rays and can cause severe health problems. Pufferfish is among world's most poisonous vertebrates
Over 30,000 fish species inhabit Earth's oceans and fresh water. Some fish species pose threats to humans or can be poisonous
Sea urchins are spiny, globular echinoderms with five-fold symmetry. About 950 species live in oceans from intertidal to 5,000 meters. Their tests are round and spiny, typically 3-10 cm across. They move using tube feet and sometimes spines for defense
Whale shark (Rhincodon typus) is the largest living non-cetacean cartilaginous fish. Average adult whale shark measures 9.7 m long and weighs 9 tonnes. Largest verified whale shark specimen was 12.7 m long and 21.5 tonnes
Starfish are star-shaped echinoderms belonging to class Asteroidea. About 1,900 species live worldwide from intertidal to 6,000m depth. Most have central disc and five arms, some up to 50 arms. Body covered with overlapping plates and covered by epidermis