sharks are fish of the group of chondrichthyes (Chondrichthyes), that is, they are animals included in a group of fish that presents the predominantly cartilaginous skeleton. These animals are generally known for their aggressiveness and for being feared by bathers around the world, however, as we will see below, not all sharks are that dangerous.
Read too: danger of the beaches
→ Shark Characteristics
Sharks are part of a very large group of fish, with several species that are differentiated by body characteristics and eating habits. Some sharks are quite small and others, like the whale shark, can grow to more than 10 meters in length.
In addition, we have species that are large predators, such as the white shark, while other species, such as the whale shark, are filter feeders and feed on plankton. In carnivorous sharks, which is the vast majority of species, it is possible to observe strong jaws and sharp teeth, which allow them to tear and swallow the meat. An interesting fact about sharks is that these animals have teeth arranged in several rows, which move to the front of the mouth when old teeth are lost.
Sharks have a hydrodynamic body, which helps with their movement. To move properly, sharks make powerful movements on their trunk and tail fin. In addition to the caudal fin, sharks have dorsal, pectoral and pelvic fins. The dorsal fins act as stabilizers, while the pectoral and pelvic fins help the animal in the difficult task of performing maneuvers.
Read too: Megalodon, a gigantic species of shark that is already extinct
Like other cartilaginous fish, the shark does not have a swim bladder, a structure related to fluctuation. To ensure buoyancy, these fish have a oil rich liver. To get an idea of the help provided by the fatty liver, it is important to mention that the liver tissue of a shark has a density of 0.95 gm/m, that is, it is lighter than water. As the liver contributes up to 25% of the shark's body mass, we see how this organ helps with the difficult task of flotation.
Despite the help of the liver, this organ alone is not capable of keeping the shark afloat, as, considering the animal as a whole, it is still considered denser than water. To ensure, then, more efficient buoyancy, he needs to swim. When the shark stops swimming, it simply sinks.
These animals have in their body structures capable of detecting their food through a perception of electrical signals that are emitted by prey. These electrical discharges are emitted by muscle contractions in the body of the prey and the shark uses its electrical perception to locate them. In addition to this important structure for capturing electric fields, sharks have keen eyesight and sense of smell. Thus, they can attack animals by sensing their electrical signals and also locate dead prey through smell perception.
When it comes to reproduction, sharks are animals that present internal fertilization. The male has a pair of organs called claspers, which are responsible for transferring sperm to the female's reproductive tract. There are sharks that are oviparous (lay eggs), ovoviviparous (retain eggs in the oviduct) and a few that are viviparous (when the shark develops inside the uterus).
→ White shark
O White shark (Carcharodon carcharias) it is a great predator of the seas and it is the fear of many people. This fear can be attributed, in part, to Steven Spielberg's film in which this animal was described as a bloodthirsty species. This incredible shark feeds on a wide variety of animals, especially fish, molluscs, turtles, penguins and seals. They are often captured, mainly for the removal of their fins, which are used to make soups. This animal is about 6 meters long and lives up to 70 years.
→ Hammer shark
Note the characteristic head of the hammerhead shark.
Hammer sharks are those animals belonging to the genus Sphyrna. These animals feature a characteristic head that helps them in swimming, being this group of sharks more agile to make sharp turns than the species that have heads with the more traditional shape.
In addition, some researchers point out that their head helps them catch food., favors your vision and provides a bigger place for your brain. The size of these sharks varies by species. Individuals of species Sphyrna zygaena, for example, can reach 5 meters in length.
→ Whale shark
O Whale shark(Rhincodon typus) is a species of shark characterized by having a robust body and a broad, flat head. Its body also has a black background, in which several light spots and stripes are observed. This shark stands out for its size, and the largest individual identified was 20 meters and 35 tons. This fish feeds by filtration and suction of planktonic animals (organisms with limited means of locomotion that live floating in water) and small fish.
Read too: Animal Kingdom Records
→ Blue shark
The Blue Shark (Prionace glauca) is a species widely distributed around the world and also heavily captured, and this factor is probably related to its high reproductive rate, when compared to other species. This species reaches a maximum size of 3.8 meters. Blue sharks are migratory and their main food is fish and cephalopods such as squid. These animals are most active at night.
→ shark attacks
Despite the fear of many people, shark attacks are a rare situation. In the United States, for example, research has shown that more people die from dog attacks than from shark attacks. This does not mean, however, that care is not necessary, especially on beaches where the occurrence of these animals has already been observed.
Among the precautions we must take, we can mention:
Do not swim at dusk or at night;
Always swim in a group;
When injured, avoid entering the water;
Avoid swimming in areas where there are many schools or concentration of fishermen.
