Remoras, Cobias & Rainbow Runners - Reef Life of the Andaman - Part 22

In this video we look at more fish that form symbiotic relationships with larger marine life. Live sharksuckers (Echeneis naucrates), a type of remora, attach themselves to sharks and other marine animals using their first dorsal fin which has evolved into a sucker. The sharksucker gets a free ride and feeds off food scraps left by the host, which also gives it protection. This is known as a commensal relationship, whereby the suckerfish benefits but the host derives neither significant benefit nor harm. Some scientists believe that the remora removes parasites etc. from the host, making the relationship a form of mutualism rather than commensalism. At various dive sites in Thailand and the Mergui Archipelago of Burma (Myanmar) we see live sharksuckers attached to zebra sharks, a whale shark, a spot-fin porcupinefish, a bridled parrotfish, and even a couple of scuba divers.

In another example of commensal symbiosis, the cobia (Rachycentron canadum) is similarly usually found accompanying larger marine animals. We see them following manta rays, blotched fantail rays, and a grey reef shark. The cobia gains some protection from the larger host, and often feeds on its faeces.