RemorasEcheneidae

Pull a remora forward and it comes away with one finger. Pull it backward and it does not come away at all.

The disc on top of the head is a fin, the first dorsal rebuilt, and it does not work the way a bathroom suction cup does. It is a shallow pad divided into rows of stiff movable slats. The fish lays the pad flat against the host and lifts the slats, dropping the pressure in the spaces between them, while the edge of each slat carries rows of tiny backward-pointing spines that bite into whatever it is lying on. After that the host does the work: drag pushes the remora back into its own slats and tightens the whole arrangement, so the faster the ride, the better the hold. To let go, the fish simply swims forward.

The grip is out of all proportion to the animal. Fishermen from the Caribbean to 🇲🇿 Mozambique and the Torres Strait fished with remoras, tying a line around the tail, dropping the fish near a turtle and hauling turtle and remora back in together. The chroniclers of Columbus described it in the Caribbean, and the practice was still in use into the twentieth century.

What the host gets out of the deal varies. Remoras take parasitic copepods off the skin, scraps from the host's meals, and its waste, and some of them are particular about the address: the white remora spends its life inside the gill chambers and mouths of mantas. The live sharksucker is the opposite, a generalist that will ride sharks, rays, turtles, boat hulls and, given the chance, a diver.

Three species are listed for this sea, and the sharksucker is the one you meet, usually already attached to a turtle.