</noinclude> <gallery perrow=3 widths="200px"> Image:Red-knobbed.starfish.arp.jpg|<center>''Protoreaster linckii''<br>(Red-knobbed Starfish)</center> Image:Sunflower sea star.jpg|<center>''Pycnopodia helianthoides''<br>(Sunflower Starfish)</center> Image:Starfish.JPG|<center>''Oreaster reticulatus''<br>(Cushion Sea Star)</center> </gallery> Starfish or sea stars are any echinoderms belonging to the class Asteroidea. The names sea star and starfish are also (incorrectly) used for the closely related brittle stars, which make up the class Ophiuroidea.They typically have five or more "arms" which radiate from an indistinct disk (pentaradial symmetry). Starfish do not rely on a jointed, movable skeleton for support and locomotion (although they are protected by their skeleton), but instead possess a hydraulic water vascular system that aids in locomotion. The water vascular system has many projections called tube feet on the bottom side of the starfish's arms which function in locomotion and aid with feeding.
