Some Things Just Go Together: Like Tacos & Tuesday, Clownfish & Anemones

Ever notice that some things just go together?  Peanut butter and jelly.  Tacos and Tuesday.  One seems to enhance the other.  What about clownfish and anemones? Turtles and batfish. Cleaner fish and their hosts.  Grouper and octopus.  Shrimp and gobies.

These too, all go together.  They are symbiotic relationships. 

By definition, symbiosis refers to "a close, long-term interaction between two or more different species, where at least one organism benefits, and the other may benefit, be harmed, or remain unaffected."

Saw this beauty in Puerto Galera (Picture by Debbie Hatch)

One of the most well-known symbiotic relationships under the sea is between clownfish and anemones. Anemones are carnivorous, feeding on tiny plankton or fish. Their stinging tentacles are triggered by the slightest touch, firing a harpoon-like filament called a nematocyst into their prey. Once injected with the paralyzing neurotoxin, the prey is guided into the mouth by the tentacles. Clownfish are immune to the anemone's sting due to a layer of mucus covering their bodies. Clownfish get a soft, safe place to live in exchange for providing the anemone with nutrients in the form of waste, and helping to keep it clean by removing parasites or bits of left over food.  They also scare away potential predators of the anemone, such as butterflyfish. While anemones can survive without clownfish, clownfish are highly dependent on anemones for survival.

My personal favorite is the pistol shrimp and goby - which I can watch for my entire 50-minute dive without getting bored.  The shrimp digs and maintains a burrow for them both to use, and the goby acts as a lookout for predators, with both benefiting from the partnership. The shrimp’s eyesight is poor, so they rely on sensory antennae to keep in contact with a goby. The goby gets a safe home, and the shrimp has his own security guard. 

Cruising the reef, Palau. (Picture by Debbie Hatch)

While maybe not such a heart-warming story, batfish and Green Sea Turtles have a type of symbiosis known as "commensalism". Here, one organism benefits, and the other is neither harmed nor helped. Batfish, which have a diet similar to the turtles (algae and seagrasses), find the turtle's poop a convenient and easy meal. It's not at all uncommon to see these fish following turtles around specifically to take advantage of a "fresh" meal. The turtle is not negatively impacted by the fish's presence or feeding habits, and may even get some small benefit from the batfish's presence as they can help clean the turtle's shell.

Octopuses and groupers have been seen hunting together. The octopus, with its intelligence and ability to squeeze into tight spaces, explores crevices and hidden areas, potentially flushing out prey. Meanwhile, the grouper's presence and size can scare prey into the open, making them easier targets for the octopus. This collaborative hunting strategy increases the success rate of both the octopus and the fish, allowing them to catch more prey.

I find things like this incredibly interesting. Can you think of other symbiotic relationships in nature?