Remora (family Echeinidae) are small fish that live on and around sharks. They eat stray bits of food left by the shark and tiny shrimp-like parasites that live on the shark's skin. They have sucker-like disks on their heads with which they attach to the shark. Both the shark and the remora benefit from the pairing, but the remore benefits much more; this is commensalism. Remora are also known as sucker fish or shark sucker.
Remoras or suckerfish are elongate brown fish in order Perciformes and family Echeneidae. They grow up to 30-90 cm long (1-3 feet), and their distinctive first dorsal fin takes the form of a modified oval sucker-like organ with slat-like structures that open and close to create suction and take a firm hold against the skin of larger marine animals. By sliding backward, the remora can increase the suction, or it can release itself by swimming forward.