Luidia clathrata is a tropical species of starfish in the family Luidiidae. It is variously known as the slender-armed starfish, the gray sea star, or the lined sea star. It is found in the western Atlantic Ocean.

Description Luidia clathrata is a large, flattish starfish, sometimes growing to a diameter of 30 cm (12 in). It has a relatively small disc and five slender arms, which are two or three times the diameter of the disc. The upper surface of the disc and arms is clad in longitudinal rows of calcified plates called ossicles, and in paxillae, pillar-like spines with flattened summits covered with minute spinules. No plates are found along the margins of the arms, these being replaced by paxillae, but on the underside, the marginal plates are large and themselves covered with paxillae. The tube feet, found in longitudinal rows on the underside, do not have suckers, but have two swollen regions. A mouth is in the centre of the underside, with an oesophagus and cardiac stomach which can be everted. The gonads are underneath the sides of each arm.