Better together: These underwater “BFFs” use teamwork to survive and thrive.
Think about what makes a good friendship. Maybe you share your snacks, look out for each other, or help your bestie reach their goals. Believe it or not, the ocean is full of similar “friendships” called symbiotic relationships—long-term bonds between two totally different species.
Just like in our world, these underwater connections come in a few different flavours:
Mutualism (The Win-Win): This is the ultimate team-up where both species benefit. Everyone walks (or swims) away happy!
Commensalism (The Sidekick): In this setup, one species gets a boost, while the other one isn’t really affected either way. It’s like hitching a ride without bothering the driver.
Parasitism (The Frenemies): This one is a bit one-sided. One species benefits, but it happens at the other’s expense. These are definitely the more “toxic” relationships of the sea.
Sea Cucumber and Emperor Shrimp
The Imperial shrimp and the sea cucumber can be seen as fast friends of the sea. The Imperial shrimp utilizes the sea cucumber for its locomotive purposes, hanging tight through waters filled with the shrimp’s food source, only disembarking to have a bite, and then climbs aboard to further its travel to the next feeding ground. This is an example of commensalism, wherein one species benefits from the other, while the other neither benefits nor is harmed.
Sea Anemone and Clown Fish
This symbiotic relationship is well-known due to the popularity of films such as Finding Nemo. The sea anemone and clown fish are a great example of mutualism, meaning both species benefit from having the other around. The anemone protects the clown fish by concealing it within its poisonous arms, as well as leaving scraps of its meals for the clown fish to consume. In return, the clown fish rids the anemone of parasites, wards away predators, and even offers nutrients by way of its excrement.
Whale and Barnacle
The relationship between whale and barnacle is yet another example of commensalism. The whale reaps no rewards from a barnacle attaching to its body, yet poses no threat to the whale. The barnacle reaps great rewards by attaching itself to a whale because of its filter-feeding nature. Like the Imperial shrimp, it stands to gain an abundant food source by attaching itself to a whale for the duration of its existence.
Decorator Crab and Sponge
Dressing up to avoid attention
There are over 700 species of decorator crabs that cover their bodies with a wide range of unexpected ornaments. But these crustaceans are not dressing up to impress or get noticed. A most striking balance is struck between the decorator crab and the sponges it, well, decorates itself with. The decorator crab does so as a means of defence, snipping bits of sponges to cover its shell as camouflage. The sponges continue about their lives, filter feeding as they normally would attached to coral or any other surface. The crab can also benefit by toxins that may be inherent to the species of sponge it chooses, as well as feeding on the algae growing around the sponge. The sponge benefits much in the way of the previous “hitchhikers”, by being exposed to many feeding opportunities based on the crab’s movements.
Manta Ray and Remora
Remoras are known collectively as “sucker fish” for their propensity to attach themselves to many different types of species, including dugongs, sharks, sea turtles, and manta rays. The remora uses its host for the usual amenities: protection, transportation, and scraps from the larger predator’s meals. The remora can also exist in mutualism with its host by cleaning its skin of bacteria and parasites.
