Parrotfishes and wrasses are small-size dwellers of the shallow waters in the Indian, Atlantic and Pacific Ocean, mainly found in reef areas. The two families used to be regarded as distinct and separate groups, but nowadays scientists consider the almost one hundred species of parrotfishes to be a subfamily of the much larger category of wrasses. The reason why the classification has been modified is that wrasses and parrotfishes share numerous features and not only in terms of habitat choice and physical appearance, but also in terms of behavior.
Both parrotfishes and wrasses are very diverse groups – the family of wrasses called Labridae includes more than 600 different species, with parrotfishes making up more than 15% of them. Most subspecies are small, usually reaching lengths under 20 cm, though there are a few species, such as the humphead wrasse, that can grow up to 2.5 m in length. Both groups are characterized by having strangely shaped mouths, and yet the mouth shape is also the feature that distinguishes wrasses and parrotfish. The teeth of parrotfish are placed on the exterior of their jaws, making the mouth of the fish look like the beak of a parrot – hence the name – while wrasses have two bony jaws with teeth pointing outwards and thick lips.
Parrotfishes and wrasses are slightly different in terms of feeding behavior as well. While wrasses are mainly carnivores, feeding on the small invertebrates left behind by larger fish as well as on coral polyps, parrotfish are predominantly herbivorous, occasionally consuming microscopic organisms they find among corals such as algae.
One of the factors that make the identification of parrotfishes and wrasses problematic is the frequent changes they undergo during their lifecycle. They both change colors several times during their lifetime, what’s more, some species even change shape, in some cases to mimic other fish and to find shelter, in other cases to attract fish of the opposite sex and many species are known to be able to change their sex, too. Sex change is usually from female to male, with larger fish that start their life as females transforming into males over time.
The two groups are different when it comes to how they take care of their young. Parrotfish release their eggs into the water, with the eggs floating freely until they find a suitable place to settle for hatching. Wrasses, on the hand, exhibit some sort of parental care after spawning – the males build nests for the eggs, ventilate the eggs and protect the nests against predators.
Some parrotfish species, especially the ones that live in the Caribbean, are known to feed on sponges, thus contributing to the protection of reef building corals. They also feed by biting off small pieces of rock which they process to extract edible materials and then eliminate the rest, being among the most important producers and distributors of sand on reefs. Some wrasse species, such as cleaning wrasses feed on the dead skin tissue and the parasites that accumulate on larger fishes, forming large cleaning stations frequently visited by “clients” such as whales and sharks.