Parrot Fish
Parrotfish
Parrotfish make up a large
group of marine species that inhabit shallow coastal waters in tropical and
subtropical oceans throughout the entire world. They are found in rocky coasts,
coral reefs, and seagrass beds, and play a significant role in bio erosion.
Parrotfish are named for their numerous amount of teeth that are arranged in a
tightly packed mosaic on the external surface of their jaw bones that form a parrot-like
beak, with which they tear from coral and other rocky substrates. Sizes vary
within the parrotfish family with the majority of species reaching 30–50 cm
(12–20 in) in length. A few species can reach lengths in excess of 1 m, and the
green hump head parrotfish can reach up to 1.3 m.
Parrotfish are detritivores
and can eat a wide variety of microscopic organisms living on and within the
substrate. The green hump head parrotfish include coral in their diets. 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. Parrotfish teeth grow continuously, replacing material worn away by
their eating habits. Their pharyngeal teeth grind up the coral and coralline
algae that the fish ingest while eating. After they digest all of the edible
portions from the rock, they excrete it as sand particles, helping to create
small islands and all the sandy beaches throughout the Caribbean ocean. The green
hump head parrotfish can produce up to 200lbs. of sand each year. While
feeding, parrotfish must be aware of predators including their biggest
predator, the lemon shark. On the Caribbean coral reefs, parrotfish are
important consumers of sponges. An indirect effect of parrotfish grazing on
sponges is the protection of reef-building corals that would otherwise be
overgrown by fast-growing sponge species.
The development of
parrotfishes is super complex and followed by a series of changes in color
(polychromatism). Most species begin life as females and then change to males.
Some species develop from male juveniles to female adults. An example is the Mediterranean
parrotfish, where the colorful adults are female and the grey colored
intermediate phase fishes are male. Another example is the stoplight parrotfish
who develop directly to males and don’t start as females. These directly
developing males usually most resemble the initial phase, and often display a
different mating strategy than the terminal phase males of the same species.
The marbled parrotfish is the only species of parrotfishes known to not change
sex. In most parrotfish species, juveniles have a different color pattern from
adults and the juveniles of some tropical species can alter their color
temporarily to mimic other species.
Parrotfish use their mucus
bubble to protect from Gnathiids at night. Gnathiids are a crustacean and their
young feed off of the blood of other fish. The parrotfish will go find cleaner
fish during the day, but at night they are highly vulnerable to these parasites
to attack them. The parrotfish form their mucus bubble at night to create an
insect net type structure to protect themselves from the larval wanting to feed
on them. The mucus cocoon will cover their entire body at night. The secretion
comes out of a large gland in their gills that is under the operculum, and is
composed of small glycoproteins that are cross linked with pyro sulfate bonds.
It takes them less than an hour to cover their bodies at night. This
combination of the two allows small molecules to get through the mucus, but not
the Gnathiid larvae. They think it is a combination of odor and isopods that
makes the other fish stay away from them at night. The energy consumption of
this secretion only uses 2.5% of their daily energy. Other defense mechanisms
that other fish have expend a lot of their energy, but the parrotfish’s method
is much more effective with less energy being spent. Since this uses such
little energy, they can produce a second mucus bubble if they need to during
the night.
There are
a few other theories for why they secrete this mucus net around themselves at
night. There are theories that it can be used as a warning signal from other
fish at night. Another theory is to act as a dust over from sediment collecting
on them at night while they sleep. The cocoon may also have some protection
from the sun’s rays to protect their skin. There is also a study that shows
eels are less likely to eat the mucus covered fish than the ones that are left
unprotected at night, although this theory has not been properly tested to show
actual results. With the mucus covered fish being so well protected, it has
raised questions about how do other fish protect themselves at night from other
predators and parasites. The parrotfish is extremely protected in the cocoon at
night and is almost never attacked by the parasites once in the cocoon.
Great post.
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