Friday, April 29, 2011

Deep sea monsters know as Angler fishs

Anglerfishes are famous for their unusual predatory technique. Their first spine have been developed into a fishing pole with a little bate in the end. The fishing pole is actually named “illicium” and the bate is named “esca”. The esca is a fleshy growth found at the end of the illicium. When a predatory fish notices the esca, it thinks that it is a suitable prey. It swims close to the esca, and is rapidly overtaken by the Anglerfish before it gets a change to swallow the esca.

There are more than 200 known species of Anglerfish in the world, and more might be found in the future since a lot of the Angler fish species inhabit great depths far down in the ocean where humans and their research equipment seldom venture. The Anglefish species are not contained in any special family or genera, they are instead spread out over several different families. They do however belong to the same order; Lophiiformes. (The order of the bony fishes.)  

Angel fish species are famous for their capability to kill and consume prey that is much larger than them selves. The ambush effect makes it possible for Angelfishes to kill large prey and their adaptable body makes it possible for them to swallow the catch. Their jaws can be distended to accommodate huge prey and their thin and flexible bones make their stomach larger. The stomach of an Angler fish is very stretchy.

As mentioned above, a lot of the Anglerfish species dwell far down in the ocean. They inhabit aphotic zones to where the suns’ light can not penetrate. A normal esca is therefore invisible. The deep living Angler fish species have solved this by entering a symbiotic relationship with a certain type of bacteria than produce light. The bacteria colonise the esca and make it glow in the dark, an example of so called bioluminescence. Bioluminescence is a common feature in deep sea living organisms and other predatory fishes in the aphotic zone will therefore assume that the small esca is a suitable prey. The rest of the Angler fish is dark and can not be detected in the aphotic environment. The light from the esca is not strong enough to illuminate the body of the fish, nor is the light from other bioluminescent organisms. The Angler fish can therefore stay completely hidden and ambush the unsuspecting predatory fish.

Deep sea Angler fish have developed an unusual method of reproduction. Once a male Anglerfish finds a female Anglerfish, he will never leave her. He attaches himself to her body using his sharp teeth and produces an enzyme that gradually allows him access to her blood stream. The two fishes will gradually melt together and the male will not hunt, he will get all the nutrition that he needs from the female Anglerfish. When she is ready to ovulate, the hormone levels in her blood will make the male produce sperm than can fertilize the eggs. In order for this method to be successful, the female Anglerfishes are much larger than the male. When the males have attached themselves to a female, they will actually deteriorate even further. One of the largest found female Anglerfishes was bigger than one yard (more than 90 centimeters). Some female Anglerfishes will allow several males to attach themselves to her.

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