Mutualism Between Big Fish & Little Fish

Large fish, such as this whale shark, have trouble grooming themselves and often rely on smaller fish for assistance.

Mutualism is a specific relationship between two different species of organisms in which each member benefits. Mutualism differs from parasitism, in which one member benefits and the other is harmed, and commensalism in which one member benefits and the other neither benefits nor is harmed.

Cleaner Wrasses

The cleaner wrasse -- also known as the bluestreak cleaner wrasse -- works along side shrimp to clean the gills, mouth and scales of client fish -- such as the reef lizardfish and groupers -- that have trouble grooming themselves. Interestingly the client fish are often predators, although they do not attempt to eat the cleaner wrasse.

Remoras

Remoras are the small fish that suck onto the outside of large sharks and manta rays. The larger sharks and rays benefit because the remoras specialized mouth can can clean parasites from scales and fins, and the remora benefits from its free meal.

Pilot Fish

Pilot fish swim ahead of sharks and unlike remoras, do not suck on to the shark's skin. By swimming close to sharks, pilot fish gain protection from predators and in return eat parasites - such as small crabs and blood-sucking worms - that may attempt to feed upon the shark.

References

• Fish Channel: Cleaner Wrasse
• South China Normal University: Ecology Chapter 15
• Green Answers: Pilot fish
• PBS Coral Reef Connections: Partners

Resources

• PBS Coral Reef Connections: Partners