The hammer shark is a very
particular animal, with a morphology that is far from that of the other
sharks and some behaviors that are decidedly different and they
constitute still today a mystery. Known in the first centuries later
Christ, was considered a real beast, to fear and to avoid. The meeting
in sea with the hammer shark was considered cause of great adversity and
its particular morphology gave birth to numerous legends..
The hammer shark is present also in the Mediterranean Sea, some samples would have been signalled in the western Mediterranean, near the Spanish coasts, Moroccan and Algerian. In Italy there would have been sightings in the waters of the Ligurian Sea and in Sicily.
The hammer shark owes its name
to the particular form of the head, flattened and lengthened to the
sides, that form two side expansions, which are sustained by important
changes of the inside skeleton. The form and the length of the hammer
change in base to the different kinds.
The hammer, being flattened,
increases the surface of the anterior part of the shark and it opposes
downward the push of the body during the swimming. Perhaps not by
chance, among all the sharks, the hammer shark is the most agile and
rapid and during the hunting becomes an infallible raider.
The nostrils, set to the
extremities of the flattened head, are of greater dimensions in
comparison to those sharks of other kinds and they would clearly give a
superior olfactive ability. (Sense of smell: the sharks nostrils, always
well visible on the inferior part of the face, are constituted by two
channels to blind fund, at the end there are cells that analyze the
presence of fragrant substances dissolved in water. The sensibilitynof
the sharks is very developed, it is thought that a shark can
individualize 1 part of blood in 100 million parts of water)
Also the eyes are found to the
extremities of the hammer and this greater distance would favor the
stereoscopic sight with a superior ability to understand the distances
and the positions in water.
The side line, organ with
which the sharks and the bony fishes perceive the waves of pressure,
that races along the sides of the animal, continuous in the hammer shark
in the region of the head and also in this case it would result more
Finally also the "sixth sense"
of the sharks, what allows them to perceive the elettro-magnetic field
of the living organisms, would result strengthened as these sensorial
cells, the Ampullae Lorenzinii, are diffused in the area of the head and
therefore mostly present in this fish.
During the hunting the use of
the hammer as real tool has been found besides for stunning and to
immobilize the prey before being devoured.
The documented attacks to
scuba divers or skin-divers are very little and also in presence of
baits the hammer shark doesn't show him particularly aggressive; a
dangerous kind remains however potentially because of the dimensions and
of the mighty teeth.
Is certain instead that the hammer shark shows to be an excellent raider, to the vertexes of the food chain, perfectly evolved and suited for the environment in which alive and able of advanced relationships with exemplary of the same kind. It is not therefore a beast or a monster to be feared and on which to create legends but a marvelous inhabitant of the submarine world..
Marco Angelozzi - www.prionace.it
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