5 curiosities about sharks – Among the many animals that populate our seas, one of the most suggestive is certainly the shark . Not everyone knows it, but sharks have lived in marine and ocean waters for 400 million years. They even appeared before the dinosaurs, which they survived. Currently, throughout the globe there are more than 465 species of sharks, although many of these extraordinary predators are now at risk of extinction, due to human action .
Equally diverse are the habitats in which sharks live . Certain specimens find their ideal environments even in fresh water. Behind these animals lie many other peculiarities, in most cases little known. In this article we will learn some curiosities about sharks .
Characteristics of sharks
Sharks are fish with a skeleton made of cartilage. For this reason they are also called cartilaginous fish . Belonging to the group of elasmobranchs , sharks are characterized by a pointed head, a tapered body and a large jaw opening. Most shark species have five gill slits on the sides of their heads. However, some species are characterized by the presence of six or more gill slits.
Sharks live in virtually every type of sea, from tropical to temperate waters. However, these predators prefer cold-water habitats, with temperatures around 11/12 degrees Celsius.
Shark Trivia
1.Sharks don’t sleep
Sharks never go into a deep sleep phase like other vertebrates. They keep their eyes open, moving more slowly but still swimming. In this particular phase, they manage to keep part of their brain at rest.
2. Sharks have predators too
Although sharks occupy a privileged position in the food chain, being at the top of it, they also have predators. Some sharks, in fact, are only about ten centimeters long. They can therefore be easily hunted by other larger fish. One example is the cat shark , a species found in temperate and tropical seas throughout the world.
Even the largest species can sometimes be preyed upon. For example, there have been documented cases of white sharks being killed by killer whales. But the “predator” par excellence of sharks remains man, mainly due to intensive fishing practices .
3. Some sharks change 30,000 teeth in their lifetime
Sharks have special teeth. They are not attached to the bone but only to the gums. Throughout their lives, sharks continue to grow rows of new teeth behind the main one, resulting in constant replacement.
A shark’s tooth lasts an average of one week before falling out. When this happens, the tooth immediately behind it moves forward to replace it. A tooth can be replaced in less than twenty-four hours. The speed with which this entire process occurs is such that some shark species can change up to 30,000 teeth in their lifetime.
4. Not all sharks are carnivores
Not all shark species are carnivorous. In fact, there are several specimens that feed exclusively on plankton to survive . These species are therefore completely harmless to other marine animals and, of course, also to humans.
5. Sharks don’t have scales
Shark skin is characterized by its hardness. It is covered with dermal denticles that in turn have an enamel very similar to that of teeth. This particular skin allows sharks to optimize their movement in water, ensuring extraordinary hydrodynamics .
Sharks: Why They Are in Danger
It is estimated that the global shark population has decreased by more than 70 percent. The decline is so high that it is now close to the “point of no return”. In addition to climate change and pollution, including noise, one of the main threats to sharks, as for the rest of marine fauna, is intensive fishing . Sharks are hunted for their liver oil, for their meat and especially for their fins, an ingredient in a soup that is very popular in Asia.
It is estimated that every year, 100 million sharks are killed or fall victim to accidental fishing. A real massacre that risks making these predators disappear, causing a series of consequences in marine habitats .
Among the most dangerous places on the planet for sharks is the Mediterranean . In the Mediterranean basin, direct consumption of shark meat is high, especially in Italy, which is among the main consumers. Very often this happens without people being aware of it. Many consumers do not know that behind common names such as dogfish , porbeagle and blue shark there are actually shark species. In many cases, people are instead victims of food fraud . For example, the fraud that sees shark slices passed off as swordfish is very common.
The overall picture has led to alarming data. In fact, 50% of the shark species present in the waters of the Mare Nostrum are at risk of extinction .
Shark Curiosities: Apps to Protect Them
On July 14, 2020, on the occasion of Shark Day , the World Shark Day , the WWF launched the Sharkulator App . The application aims to discourage as many people as possible from consuming shark fin soup. The particular initiative is based on scientific data regarding the mortality of sharks fished in an unsustainable way.
Another example of an App designed to protect sharks can be found in SharkApp . This is a Citizen Science project , curated by researchers at the Stazione Zoologica Anton Dohrn in Naples , to actively involve fishermen and sea enthusiasts in the protection of these exceptional animals.
The application, available for both iOS and Android devices, invites users to report sharks encountered by chance by sending a photo and the location where the sighting occurred. The data collected constitutes an extremely valuable source for researchers who, thanks to the mapping , have the possibility of carrying out targeted interventions to protect sharks.