A pink shark with blue fins that swims up to 1000 m of depth?
It is not imagination but
reality, that describes a particular animal, known for the first time in
1898 and that takes the name of goblin shark (Mitsukurina owstoni).
The goblin shark has lengthened
and flattened face, to form of blade, with small eyes without nictitant
membrane. (Note 1)
The fins have a bluish coloration, the pectoral fins are short and wide, the two dorsal fins rounded off and smaller than the ventral ones and of the anal fin, also this rounded off. The spiracles are present and they are of small dimensions. (Note 2)
From the first descriptive
elements we can be realize that the goblin shark probably is not a great
swimmer, as other belonging sharks to the order Lamniformes (es: white
shark, Carcharodon carcharias and mako shark, Isurus
The anterior teeth of the goblin shark are long, smooth and thin while those back teeth are stronger. This disposition suggests that its preys are constituted above all by soft small fishes, cefalopods and shellfishes, preys captured and held back by the anterior teeth and then shattered by back teeth.
The goblin shark seems to be
helped in the search and capture of the preys by its lengthened face,
that can contain an elevated number of Ampullae Lorenzinii
3), and from a system of extreme jaw protrusion.
The mechanism of jaw protrusion
is filmed for the first time in 2008: in the video, that is here
proposed, a small goblin shark is stimulated to bite the forearm of a
scuba diver to put in prominence the complete jaw movements.
The goblin shark is present in
some areas of the Atlantic ocean, in the waters that bathe South Africa,
Portugal and France, in the Pacific ocean, from Japan to Australia up to
the New Zelanda. The boglin shark is a abysmal creature, swimming in
depth among 270-950 m, reaching 1300 m. Rarely has been sighted swimming
in low depths.
Goblin shark (Mitsukurina owstoni) distribution
Note 3: in the abysmal depths, where the goblin shark swims, brightness is practically absent and in fact the small eyes make to understand that this sight of is not the winning weapon to find preys. Ampullae Lorenzinii are very important to find preys, present in the ample surface of the lengthened face. We remember that the Ampullae Lorenzinii are organs that take contact with the outside through small and numerous holes, present especially in the region of the head, full of a gelatinous conductor substance, in communication with nervous terminations. In this way the shark has the ability to perceive the electric fields produced by the animals (therefore to also individualize preys under the sand or in absence of light) and probably to recognize its own position in comparison to the Earth magnetic field. After having also individualized the prey with the help of the Ampullae Lorenzinii, the goblin shark tries to capture it with the fast movement of extension (protrusion) of the jaw, as already described.
Note 1: the nictitant membrane is an eyelid that is closed above the eye. The sharks that don't possess it can rotate back the eyes. (es: white shark Carcharodon carcharias and mako sahrk Isurus oxyrinchus)
Note 2: the spiracle a small hole set behind the eye of these animals whose open/close is connected to the action of an unintentional muscle.
Note 4: the 30% of the sharks has a oviparous reproduction, that is when the female deposes outside the eggs; around 50% has a aplacental viviparous reproduction, that is when the female produces the eggs that develope inside her body and the small sharks go outside completely formed; the remained 20% has a placental viviparous reproduction, that is when the embryo is in contact with her mother through a primitive placenta
Middle dimension: 200-300 cm
Bibliography: "Sharks & Rays, Elasmobranch
Guide Of The World". Ralf M. Hennemann,
Marco Angelozzi -