Keeping the underwater world clean and healthy is a full-time job for some species. Of course, a balanced ecosystem involves the participation of every life form, but there is also a whole host of creatures that have specific roles – cleaning other animals, filtering the water, and keeping some other species in check.
Scientists have revealed the importance of some of these cleaning species – according to a study published in the journal Current Biology, individual rabbitfish, for example, visit cleaners every five minutes in some places! Sadly, these vital underwater inhabitants are often the first to disappear when the environment becomes too polluted.
Meet the underwater “clean team”! Some are part-timers, others clean around the clock, and all of them matter.
Some of the most dramatic and intimate encounters with marine life occur on visits to established “cleaning stations”. These are places where animals will go to have parasites, dead skin, bacteria and mucus removed by other species. Cleaners help other species avoid getting infections, especially around wounds.
Cleaning stations can be low key – little patches of reef inhabited by cleaner shimp and used by fish such as groupers and moray eels, or turtles and reef sharks. Or, they may be dramatic sea mounts inhabited by schools of angelfish and visited by ocean wanderers like mantas and pelagic sharks.
In some places animals will aggregate in huge numbers on cleaning stations, and there appears to be some kind of understanding and communication about taking turns, and a hiatus on predator/prey behaviour.
Studies at manta ray cleaning stations by the Marine Megafauna Foundation have shown that different species specialise in cleaning different sections of the mantas’ bodies. For example, they found that Klein’s butterflyfish (Chaetodon kleinii) specialise in cleaning any bite wounds that a manta may have, whereas cleaner wrasse (Labroides dimidiatus and Labroides bicolor) attend to inside the mouth and around the gills, and moon wrasse (Thalassoma lunare) specialise in picking off calagid copepods from the mantas’ ventral surface.
These places are often well established, and some have become big attractions as dive sites. It is imperative that when visiting cleaning stations, divers follow strict codes of conduct to prevent disturbing the animals’ natural behaviour.
Sponges have one of the most vital roles on the reef – they filter huge quantities of water, removing impurities. Some sponges also produce massive amounts of oxygen, around three times what they consume.
2. Sea snails
Astrea, turban, and nerite snails are just some of the sea snail species that keep pesky turf algae and cyanobacteria under control, preventing it from overgrowing and smothering corals and other benthic life. Not all sea snails are so benign, however – some snails, like the infamous Drupella, and renowned coral killers!
Distribution: Atlantic, Indian and Pacific Oceans, Red Sea
There are more than 100 species of butterflyfish. They are all members of the Chaetodontidae family and are also opportunistic cleaners, though again, for most species, the behaviour is more common amongst juveniles. Most adult butterflyfish tend to form monogamous mating pairs.
Distribution: Warm, tropical waters worldwide, Atlantic, Pacific and Indian Ocean
Nearly all species of angelfish will “work” on cleaning stations during their juvenile phase. A few species will even continue to fulfil the role of cleaners into their adult life, such as the clarion angelfish. Some angelfish, in the Caribbean for example, feed on fast-growing sponges, and keep them in check.
5. Sea Cucumbers
The humble holothurian feeds by extracting the nutrients it needs from the oceans’ sediments, filtering any organic matter through its digestive tract, and then ejecting the sediment in a cleaner, more homogenous form. Some sea cucumbers will process more than 45 kilos of sediment a year, and so, considering that they are thought to make up around 90 percent of deep-ocean macro-fauna, they play a hugely significant role in purifying the seabed.
Distribution: Tropical seas worldwide
A “keystone” species, parrotfish play an essential role on the reefs, spending around 90 percent of their day feeding by scraping algae off the reefs. They also expel coral sand, which, in turn, keeps beaches healthy. Unfortunately, in many places, parrotfish have been overfished for food, leading directly to the decline in reef health in these areas.
Distribution: Tropical seas worldwide
Surgeonfish species like blue tang and brown surgeonfish are often seen cleaning other fish, and even turtles, removing unwanted algae from their shells.
8. Neon Gobies
Distribution: Western Atlantic, from Florida and Bermuda, the Bahamas, Caribbean and Gulf of Mexico, coasts of Central America and northern South America
Sometimes mistaken for cleaner wrasse by the uninitiated, neon gobies (small gobies in the Elacatinus genus) pick parasites and dead skin off other fish in much the same way as the little wrasse do. Elacatinus sp. usually form monogamous pairs, and studies have suggested that the females do more cleaning than the males, probably as a result of having greater energy and nutritional needs for reproduction.
9. Cleaner Wrasse
Distribution: Indian Ocean, Pacific Ocean, Red Sea
One of the most well-known underwater cleaners, cleaner wrasse will “dance” to advertise their “services” at specific stations. These bright little fish remove parasites from the animals that visit them, getting into hard-to-reach places like gills and mouths. There are five species cleaner wrasse in the Labroides genus, but perhaps the most familiar is the blue-streak cleaner wrasse, Labroides dimidiadus.
10. Cleaner Shrimp
Distribution: Worldwide, though data from the polar regions is limited
People commonly use the term “cleaner shrimp” to refer to crustaceans that are members of three families: Hippolytidae (which includes the Pacific cleaner shrimp, Lysmata amboinensis), Palaemonidae (including the spotted Periclimenes magnificus) and Stenopodidae (which includes the banded coral shrimp, Stenopus hispidus). Cleaner shrimp often live in little crevices in the reef, and some will perform a rocking dance to advertise their services. They are excellent (but not exclusively) marine dentists, trusting and being trusted by predators like moray eels to attend to their teeth.
Distribution: Southern Hemisphere from Antarctica to Australia, South Africa and South America, with four species in the North Pacific from Hawaii to Japan, California and Alaska, and one species between the Galápagos Islands and South America
Anecdotal evidence suggests that there may be a direct relationship between albatross and ocean sunfish (Mola mola), with the fish basking at the surface and the birds descending to clean them of parasites. Other seabirds have also been spotted engaging in similar behaviour, helping remove unwelcome hitchhikers from other marine megafauna, such as cetaceans.
Check out Scuba Diver AustraliaAsia + Oceanplanet “Blue Green Edition” Issue 2/2017. The issue itself is dedicated to conservation and honours the winners of the Bluegreen360 Awards 2017, presented to those businesses and individuals committed to eco-friendly practices and marine conservation.