Angler fish . monster from the deep

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.