This sea star gets its common name from its smooth skin. Its soft skin can exude a mucous making it feel slippery to the touch. The leather sea star does not have spines like other sea stars, but six-eight rows of papulae, small feathery sacks used for respiration on each of its five arms. Sea stars are unique because unlike most other animals they do not have blood but instead use sea water to pump around their bodies. Unlike many other sea stars, Leather Stars swallow their prey whole and digest it internally.