Parrotfishes

Parrotfish got their name from having a fused-beak structure– like a parrot!
A parrotfish’s diet is primarily algae. To eat, they use their beak to pulverize coral to reach the algae-filled polyps hiding in the coral reefs.
Whether they feed on coral, rock or seagrasses, the substrate is ground up between the pharyngeal teeth.
Sand is ground-up, undigested remains of coral.
So, thanks to parrotfish we are able to have sand on the seafloor, sand bars, and amazing beaches all around Cozumel.

There are approximately 95 different species of parrotfish.
They are normally quite colorful fish and can be commonly seen in blues or greens, with accents of pink, purple, yellow and red.
Most species of this fish range from 25 to 50 cm in length, but they can be anywhere from 12 cm long to well over  1.2 meters and weigh up to 20 kg!

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Habitat and Distribution

Parrotfish prefer living in shallow seas, because coral grows best in areas with lots of light. They can be found in both tropical and subtropical habitats.
Their favorite ecosystems are coral reefs, but they also live among seagrass beds and rocky coastlines.
Various species of this fish can be found in tropical and subtropical oceans worldwide. These fish are found commonly in the Atlantic, Pacific, and Indian oceans.
The highest species variety is found in the Indo-Pacific ocean regions.es are found primarily in tropical waters throughout the Atlantic

Parrotfishes are found primarily in tropical waters throughout the AtlanticParrotfishes are found primarily in tropical waters throughout the Atlant

Behavior

Some parrotfish species secrete a mucus cocoon at night.
Prior to going to sleep, some species extrude mucus from their cheeks, forming a protective cocoon that envelops the fish, presumably hiding its scent from potential predators.
This mucus envelope may also act as an early warning system, allowing the parrotfish to flee when it detects predators such as moray eels disturbing the membrane.
The skin itself is covered in another mucous substance which may have antioxidant properties helpful in repairing bodily damage or repelling parasites.

Parrotfishes are most well known for their complex social structures. Most are organized into male-dominated harems but others breed cooperatively or in pairs.
Some parrotfishes are highly territorial while others are mainly nomadic, with the home range increasing as the size of the fish increases.
Large foraging groups of up to 500 individuals form for spawning and to deter predators while feeding.
Parrotfishes feed continuously throughout the day and seek shelter in reefs at night.

Diet

Parrotfishes are primarily herbivorous, grazing intensively on dead, algae-coated coral, vegetable material, and in some species sea grasses, sponges and coral polyps.
Key to the success of parrotfishes is their ability to take up plant material, detritus and calcareous sediment and process it through the action of the pharyngeal jaw.
This chewing mechanism grinds ingested material into fine grain sand and breaks down algal cells, releasing the cellular material for digestion. 

Life Cycle

Parrotfishes utilize some of the most complex and unusual reproduction systems known to fishes. Males can be either primary, i.e. born male, or secondary, i.e. females that have undergone sex change.
In some species there are no secondary males while in others all individuals are born female (monandric) and change sex when necessary. In the most complex systems, species are diandric – both primary and secondary males exist in the population.
In these species, individuals proceed through three distinct phases, marked by color differences.
In fact, the color differences are so pronounced that for over 200 years researchers regarded some phases as distinct species.
Sexually immature and drab colored juveniles represent the first phase.
The second, known as the initial, phase (IP) can include sexually mature males or females, which are impossible to tell apart without internal examination or observation during spawning.
The terminal phase (TP) includes only mature males, which display brilliant colors. TP males usually dominate reproductive activity through a harem-based social system.
The death of a TP male serves as a social cue for an IP female to change sex and behavior.
The morphology and behavior of IP males may also change in response to the death of a TP male. In some cases IP males attempt to infiltrate a TP male’s harem by masquerading as a female. In the so called “sneak spawning” attempt IP males follow spawning pairs into the water column and release a large cloud of gametes at peak spawning in an attempt to overwhelm fertilization by the TP male. IP males are well equipped to perform “sneak spawning” as they have larger testes and so are able to produce more gametes, while TP males have smaller testes and rely on aggression to deter other males.

Reproduction

Parrotfishes spawn year-round, usually at dusk. However, peak spawning occurs in summer for many species and there is evidence that some species have defined non-spawning periods.
Many species migrate to the outer edges of the reef to spawn but some spawn within defined territories.
There is evidence that some scarids respond to the lunar cycle during spawning, but in others, spawning correlates closely with high tide, regardless of the time of the lunar month.
In species that spawn several times during the day, the tidal cycle is followed closely since this is the optimal time for egg dispersal.

Ecosystem Roles

Parrotfishes have a major impact on coral reefs through intensive grazing and associated bioerosion.
The grazing patterns of large schools of parrotfish have the effect of selecting for certain species of corals and algae, and preventing algae from choking out corals.
Many parrotfishes feed on calcareous algae (algae that are high in mineral calcium) growing on dead, exposed coral by biting off chunks and turning them into a fine paste.
This type of grazing contributes significantly to the process of bioerosion and the creation of sediment on reefs and beaches.
It has been calculated that a single large Rainbow Parrotfish consumes over one cubic meter of coral skeletons per year, and turns it into fine sediment.

Their feeding activity is important for the production and distribution of coral sands in the reef biome, and can prevent algal overgrowth of the reef structure.