Zoo-Ology: Goin' to the shark wash
By Judie Farnsworth
You pull into the car wash, pay and move forward. Car in neutral, antenna down? Sit back and relax during the cleaning process.
What if you're a shark or a manta ray - you've some algae in your gills, dead skin on your belly and need a bit of sprucing up? Why of course, you'd head for the nearest cleaning station.
Actually, many species of fish, sea turtles - even hippos - visit these areas. They know where to go and who to look for.
Cleaning stations are specific areas most often associated with coral reefs and seamounts (underwater mountains). They might be found under large clusters of seaweed or in a river or lagoon. The cleaners are species of fish including wrasses, gobies and cleaner shrimp that feed on parasites, algae and other materials that can be harmful.
Gills, vents and other body parts need to be kept free of foreign material for proper breathing, hunting, swimming, eating and mating.
Cleaning stations are amazingly business-like. Studies have indicated that many of the cleaner fish may move in a particular way and have colorful markings, usually stripes, which help them advertise their services. Visitors behave in a proper manner.
A fish swims in and strikes a pose. Species may have different positions that indicate they are ready to be cleaned. A shark, for example, assumes a heads-up standing position, paddling with its caudal fin. Sometimes it exhibits a twirling motion.
In order to maintain this cleaning position in a current, the shark may have to swim out and then back again. The cleaners continually retreat and regroup.
Manta rays stay very still.
Cleaning times vary with clientele. It may take several hours to clean a manta.
For the fish that's shy, territorial or that doesn't get out much, there are cleaner species that travel - not all house calls are things of the past.
When a fish is being cleaned, its gills are flared and its mouth open, but not enough to suggest feeding. The cleaners swarm around the body, even in and out of the gills and mouth (where they pick food bits from the teeth). They're apparently unconcerned about the potential for becoming dinner. Fish species that are normally aggressive don't attack the cleaners at a cleaning station. It's not a buffet except for proper cleaners.
There may be an occasional rotten apple in the area - alas, that's life. An unscrupulous fish that mimics the appearance or behavior of cleaners may chomp on a visitor, but this is an exception.
A researcher at a particular cleaning station at the Great Barrier Reef watched more than 1,000 sharks and observed no feeding or chasing behavior. This is a wonderful example of a type of symbiosis called mutualism - where each individual benefits from a biological interaction.
These areas can be very helpful to biologists studying species populations and looking for signs of potential problems.
Divers and snorkelers can see spectacular numbers and species at a cleaning station. Another wow feature in our natural world.
Judie Farnsworth is a longtime volunteer at the Texas Zoo specializing in educational programs.