BUTTERFLIES
The butterflyfish are a group of conspicuous tropical
marine fish of the family Chaetodontidae. Found mostly on
the reefs of the Atlantic, Indian and Pacific Oceans,
butterflyfish are fairly small, most from 12-22 centimetres in
length. The largest species, the lined butterflyfish
(Chaetodon lineolatus) grows to 30 cm. There are
approximately 127 species in eleven genera. They should
not be confused with the freshwater butterflyfish of the
family Pantodontidae.
Butterflyfish are named for their brightly coloured and
strikingly patterned bodies in shades of black, white, blue,
red, orange and yellow (though some species are dull in
colour). Many have eyespots on their flanks and dark
bands across their eyes, not unlike the patterns seen on
butterfly wings. Their deep, laterally compressed bodies
are easily noticed through the profusion of reef life, leading
most to believe the conspicuous coloration of butterflyfish
is intended for interspecies communication. Butterflyfish
have uninterrupted dorsal fins with tail fins that may be
rounded or truncated, but are never forked.
The family name Chaetodontidae derives from the Greek
words chaite meaning "hair" and odontos meaning
"tooth." This is an allusion to the rows of brush-like teeth
found in their small, protrusile mouths. Butterflyfish closely
resemble the Angelfish of the family Pomacanthidae but
are distinguished from the latter by their lack of preopercle
spines (part of the gill covers).
Their coloration also makes butterflyfish popular in the
aquaria hobby. However, most species feed on coral
polyps (corallivores) and sea anemones; this poses a
problem in most reef tanks where a delicate balance is to
be maintained. Species kept in the hobby are therefore the
few generalists and specialist zooplankton feeders.
Generally diurnal and frequenting shallow waters of less
than 18 metres (some species found to 180 metres),
butterflyfish stick to particular home ranges. The
corallivores are especially territorial, forming mated pairs
and staking claim to their own head of coral. Contrastingly,
the zooplankton feeders will form large conspecific
groups. By night butterflyfish hide amongst the crevices of
the reef and exhibit markedly different coloration than they
do by day.
Butterflyfish are pelagic spawners; that is, they release
many buoyant eggs into the water which then become part
of the plankton, floating with the currents until hatching.
The fry go through what is known as a tholichthys stage,
wherein the body of the postlarval fish is covered in large
bony plates extending from the head. This curious
armoured stage is seen in only one other family of fish; the
Scatophagidae (scats). The fish lose their bony plates as
they mature.
From Wikipedia, the free encyclopedia
