Arapaima
Scientific classification
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Osteoglossiformes
Family: Osteoglossidae
Subfamily: Heterotidinae
Genus: Arapaima
Species: A.
gigas
The
arapaima originates from South America. It is a living fossil (Living fossils
are organisms that have remained essentially unchanged from earlier geologic
times and whole close relatives are usually extinct or has none). The tropical
freshwater fish is among the largest freshwater in the world, reaching lengths
of more than 2m and weighing over 100kg.
Arapaima feeds on fish, crustaceans and small animals walking on the
shore, a predatory fish. They prefer hunting close to the surface, as this
allows them to catch the small animals, as well as breathe in air. They have
labyrinth organ, a much-folded suprabranchial accessory breathing organ rich in
blood vessels and open into the fish’s mouth, making it an air-breather too.
This makes them able to survive in the Amazon River (where they live wild)
which has oxygen-deprived water.
Arapaima reproduces by spawning. Their life cycle is hugely affected by
the geographic range that they inhabit in, by the seasonal flooding that
occurs. Arapaima lay their eggs when water levels are low, and build a nest in
muddy bottomed areas. The water rises then eggs hatch, offspring can grow well
during flood season. The male is a mouthbrooder, it keeps the young protected
in its mouth until they are old enough. The female protects the male and the
young by fending off predators.
Arapaima plays an important role to humans. They are often fished as a
food source, as they are huge and have little bone in the meat. Since arapaima
needs to swim up to the surface to breathe air, they are often harpooned and
clubbed dead. With a body meat percentage of more than 50, they can yield up to
70kg of meat per fish. Their meat are said to be delicious, making them widely
fished for. They are also used as aquarium fish, and much special care is
needed as they are gigantic. Large space and resources are needed to keep them.
Their tongue supposedly has medicinal values in South America, and is mixed
with other medicinal products which are able to kill intestinal worms.
However, due to humans over harvesting of arapaima from the wild, their
quantities have dropped severely over the years. It is not endangered, but it
is becoming rare. It is a good thing to see Brazilian government taking actions
by banning commercial fishing, but people still do it illegally. As people
begin to control their excess harvest, we would (hopefully) be able to see them
in the future.
White and Black tipped Reef Shark
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| Black-tipped Reef Shark |
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| White-tipped Reef Shark The white and black tipped reef sharks are easily recognisable due to the tell-tale white and black tips of their dorsal fins. They are relatively small sharks that grow on average not more than 2.0m. They are saltwater sharks and can be found mostly amongst the reefs where they hunt at night. Their hard protective scales provide protection when they squirm in between coral to catch fish hiding inside. They must consistently swim to breathe because by doing so , the movement of water through the gills is the only way through which the shark can breathe. |
African Lungfish
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| Sign in Underwater World, Sentosa Singapore |
The African Lungfish is a species of Lungfish that is found unique to Africa. Their largest species reach to about 200cm in length. Because they live in an environment where oxygenated water is a rarity, lungfishes have developed a unique adaptation to counter that problem. They have developed a 'lung' which is directly connected to the alimentary canal. This 'lung' is used for breathing. It is actually a specialized version of the swim bladder.
The African Lungfish has totally no gill at all and relies solely on its lungs for gaseous exchange.
.JPG) |
| Body of a Lungfish |
The African Lungfish is a carnivorous animal that usually feeds on crustaceans and molluscs.
Goby
Goby, one of the largest family fish, are commonly found in tropical and temperate regions around the world, and commonly on many of Singapore’s shores. They are among the smallest vertebrates in the world, and camouflage well with sand and mud. Being shy creatures, they and hide into holes or rocks at the slightest sign of danger, making them very difficult to spot.
They usually dwell in the bottom of the seas, feeding on very small creatures like planktons, or filter micro-organisms from the sand. Despite being fast when hiding, they are mostly not very fast swimmers, with missing swim bladder and having cylindrical body shape, instead of streamlined body shapes. They also rely on fins to grasp tightly on surfaces, like a suction pad. Great camouflage and large eyes high up on the head help them in spotting and avoiding predators.
Gobies are vital in the good chain, serving as primary (sometimes secondary) consumers. They have been important indicators on whether a marine ecosystem is under threat, as many of them would disappear if an ecosystem is unstable. Also, they make up about half of a marine life, without them other species would be gone soon.
Due to their relatively simple caring and huge quantities, they have been kept as pets in aquariums often.
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| Ikan Ubi or True Goby References: hasnulyakin.blogspot.com |
One interesting symbiotic interaction of a Goby that we witnessed on our trip to Pulau Hantu, was the interaction between the Sand Goby and the Snapping Shrimp. The Snapping Shrimp digs a burrow in the ground where it lives. It 'employs' a Goby to keep watch at its entrance whenever it is at home. Since the Snapping Shrimp is near blind, it requires the Goby as its eyes. Therefore, whenever a predator approaches, the Goby would rush into the burrow dug by the Snapping Shrimp thus giving the shrimp a sign that it too must hide for danger is approaching. It is able to detect the movements of the goby by placing one of its antenna on the goby's body.
Therefore, the Snapping Shrimp gets shelter and the Snapping Shrimp gets protection form oncoming danger.
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| Sorry for sideways picture. Goby is circled out. |
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| Lion Fish at Underwater World Sentosa,Singapore |
Lion Fish
Lion Fishes are easily recognizable by their venomous fins that it shows off to ward away would-be predators. These small fish rarely grow to over half a metre in length. They can mostly be found in reefs in the Altantic Ocean where they may have been unintentionally introduced. Lion fish usually feed on smaller fish although their diet does included molluscs.
hasnulyakin.blogspot.com
http://en.wikipedia.org/wiki/Arapaima
http://en.wikipedia.org/wiki/Protopterus
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