• Origins of the Shark
• Shark morphology
• Shark classification
• The Tiger Shark
• The Mako Shark
• The White Shark

The Shark has been swimming in the oceans for more than 400 million years , it has survived the most important environmental changes, demonstrating great evolutionary capacities.

Origins of the Shark

Sharks made their appearance in the Devonian period of the Paleozoic (410-360 million years ago) and we could consider them the most ancient fish that swim in the seas of our planet. Their primitive structure, which has remained unchanged over time, has allowed them to survive the geological eras and arrive as they are today.

Shark morphology

Sharks are considered to be very dangerous predatory fish , of great size and strength beyond mankind. Their morphological structure can be divided into 3 parts: caudal , comprising from the pelvic fins to the caudal fin, abdominal , referable from the pectoral fins to the caudal and cephalic region , with muzzle, mouth, nostrils, spiracle and gill slits.

Their size can vary, in general they measure just over a meter, but there are species such as the pygmy shark which measures around 20cm and the whale shark which reaches 18cm in length.

Shark is a cartilaginous fish , biologically defined as ” chondrichthy “: its skeletal structure, in fact, is not made up of bones but of calcified cartilage, a characteristic that makes it lighter and more elastic.

The Shark does not have a swim bladder , an organ designed to modify the diving-flotation attitude, because in the evolutionary history of fish it appeared in later times in fish with a bone structure. To take over this activity, the shark, in addition to being able to count on the lightness and flexibility of its structure, helps itself with the pectoral fins and the tail that provide propulsion to the movements of this giant.

Another fundamental element to control the attitude of the shark in the water is squalene . It is an oil that secretes in the liver and which is of lower density than water; this allows him to swim very easily, despite his size.

The body is then covered with imbricated scales , called placoids, whose tip is turned towards the tail as a sort of hydrodynamic structure that dampens the friction with the water, and favors the rapidity of movements. The curiosity of these placoids is that they cover the dermal surface of the shark up to the mouth and become an additional row of teeth.

But are sharks mammals? There are really many species of sharks and only some behave as viviparous , so the baby is given birth and fed as it happens for mammals. Most sharks, on the other hand, are oviparous (they lay eggs) or ovoviviparous (the egg remains in the mother’s womb, the baby also feeds on the egg and once mature it is given birth).

Shark classification

The world of sharks is complex . There are indeed many species with similar basic characteristics and differentiations that structure their classification.
Kingdom: Animalia ; Phylum: Cordata ; Subphylum: Vertebrata ; Class: Chondrichthyes.  From here opens up a very vast differentiation on the Domains of the different species.

Here are the main and perhaps best known orders:

• Pristiophoriform : Saw shark (six-gilled, long-rostrum, short-snouted).
• Sharks : Cook’s Spiny Shark, Pygmy Shark, Velvety Shark.
• Carcariniformes : Gray reef shark, Brown shark, Tiger shark, Hammerhead shark.
• Lamniformes : Mako Shark, Basking Shark, White Shark.

There are some sharks that are particularly “famous” because they are the protagonists of disturbing films, or renowned because they are typical of some tourist locations beyond coral reefs.

The Tiger Shark

The Tiger Shark can reach considerable dimensions, from 230 cm to 6 meters. It is characterized by a short and wide muzzle. The pectoral fins are proportionally small. The back is gray-brown while the belly is white.

On the sides it shows dark, brindle streaks , in fact. The teeth are particular and typical of the tiger shark: cockscomb with curved cusps on the outside. It feeds on crustaceans and bony fish that it intercepts on the sandy bottoms, and sea birds. Sometimes even small sharks.

The Tiger Shark lives in both the eastern and western coastal areas of the Atlantic, the Pacific Ocean and the Red Sea. In fact, it prefers temperate and tropical waters. It can also make its appearance in shallow waters, at the mouths of rivers, in port areas.
It is a shark considered dangerous, but only because it tends to approach man easily out of curiosity and not aggression, it is its size that makes it fearful. It is advisable not to approach it spontaneously and not to think about feeding it, since the distance would disappear completely with harmful results.

The Mako Shark

This tapered and hydrodynamic shark is considered the “Ferrari of the sea” : it is able to travel for over 3000 km at a speed of 50km / h with shots at 70 km / h to capture prey and is able to leap completely out from the water up to 8 meters high. It is one of the 5 most dangerous sharks for man , it has a considerable size, up to 4 meters in length.

Characterized by a fusiform structure, with small pectoral fins, the back is dark gray or blue and a candid white belly, large dark eyes, and pointed triangular teeth.
The Mako is carnivorous , it feeds on squid and oily fish, but it does not disdain large fish such as swordfish. It does not eat humans, but a bite of it can be easily lethal.
This type of shark prefers to swim in deep water, in temperate and tropical areas. It is also present in the Mediterranean.

The White Shark

The white shark is the predator par excellence , powerful, powerful, direct descendant of the prehistoric megalodon shark. The White Shark is also called shark for its habit of holding its prey firmly between its teeth and wiggling its head to permanently stun it, as dogs usually do.

The White Shark can measure up to 6.5 meters and even weigh 1.5 tons and is the protagonist of the famous film by Steven Spielberg . He has large dark eyes, sometimes blue, the muzzle is conical and prominent. The caudal fin is characterized by a half-moon shape, and the dorsal fin is triangular. The belly is white while the back is generally gray-brown.

This Shark adapts to all seas, from tropical waters to cold waters that it prefers because here among penguins, seals and sea lions, it finds its favorite prey. It also lives in the Mediterranean , an area it prefers to reproduce is south of Sicily. It is possible to identify it in Australia, in South Africa, in California, in the waters of Mexico.

The White Shark enjoys an undeserved fame, it does not attack humans, but it is not recommended to approach and touch it, especially on the pectoral fins. He moves slowly and has a hard time turning fast in tight spaces which could cause him some behavioral stress. Divers must therefore be careful of many factors when crossing this shark so it is always recommended to move away with slow movements.