| Phylum Chordata
> Subphylum Vertebrate > fishes |
Filefishes
or
Leatherjackets
Family Monacanthidae
updated
Aug 08
if you
learn only 3 things about them ...
They can change colours and patterns to match the surroundings.
They have a stiff dorsal spine and leathery skin instead
of scales.
Small
ones (2-3cm) are common in seagrasses. Watch your step! |
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Where
seen? These strange-looking fishes are quite commonly seen
on many of our shores, especially in areas with seagrasses and among
coral rubble. They can be quite large but are hard to spot as they
blend in well with their surroundings. Some tiny filefishes are hardly
bigger than a seagrass leaf and are often the same colour as the seagrasses!
So do watch your step to avoid squashing these small fishes.
What are filefishes? Filefishes
belong to Family Monacanthidae. According to FishBase:
the family has 31 genera and 95 species. They are found in the Atlantic,
Indian and Pacific Oceans. They range from small fishes about 2cm
long to giants 1m long!
Features: Adults 10-30cm.
Body flattened sideways and disc-shaped to rectangular. Eyes are high
on the head. The gill openings are just slits.
There is a single long stiff dorsal spine, usually with downward pointing
barbs on the edges. This feature gives it its scientific name: 'mono'
means 'one' and 'canthus' means 'thorn'. The dorsal spine
can be locked upright to wedge in crevices, safe from predators and
from being swept away by currents. When not in use, the spine is folded
away into a groove on the body. Most have a second dorsal spine but
this is usually small.
The scales are small and have prickles on them. So the skin feels
leathery and rough, like sandpaper. These fishes are sometimes also
called leatherjackets. Some have hairy or feathery bits sticking out
of their skin that help break up their body outline.
Filefishes can't swim fast, aside from a short burst of speed to escape
predators by using their tails. Otherwise, they swim slowly by undulating
their other fins. Most rely on camouflage to avoid predators. They
can change colours and patterns to match their surroundings. The flattened
body allows them to slip quietly among seagrass or squeeze into crevices.
These fishes often flatten out against or 'wrap around' sponges, rubble
and other large objects. They are then really hard to spot.
What do they eat? Filefishes eat
small bottom-dwelling animals like small prawns. They also nibble
on seaweed, seagrass and immobile animals like bryozoans and ascidians.
The small mouth at the end of a pointed snout allows them to suck
small prey out of their hiding places, or reach into crevices to nibble
on edible bits. Some have large prominent teeth.
Filefish babies: Many filefishes
lay eggs that settle on the botton, onto a site prepared and guarded
by the male or both parents. Some subtropical species may release
their eggs into open waters.
Human uses: Filefishes are edible
and eaten in some traditional dishes. Unlike most other edible fishes
which are scaled before we eat them, for filefishes, the rough skin
has to be 'peeled' off first.
Status and threats: None of our
filefishes are listed among the threatened animals of Singapore. However,
like other
creatures of the intertidal zone, they are affected by human activities
such as reclamation and pollution. Over-fishing can also have an impact
on local populations. |
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Some are tiny!
Changi, Aug 07
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Family
Monacanthidae recorded for Singapore
from
Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity
in Singapore.
*Lim, Kelvin K. P. & Jeffrey K. Y. Low, 1998. A Guide to the Common
Marine Fishes of Singapore.
**from FishBase
+from our observation
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Filefishes
commonly seen awaiting identification |
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