Animals

Types of sharks: how many there are and species

Commonly known as sharks or sharks, cartilaginous fish belonging to the superorder selachymorphs are one of the most surprising animals studied by the scientific community, both for their predatory abilities and for their high cognitive capacity. In this broad group represented by 8 orders at present, it initially included another 7 orders of species that have become extinct throughout the evolution of life on Earth, both due to natural and anthropic causes.

Sharks classification

When it comes to knowing the classification of sharks, we must take into account the complete classification of these animals with respect to their location within the complex evolution of the rest of living beings with which they share a common evolutionary history, something that is possible to know starting from your taxonomy:

  1. Kingdom Animalia .
  2. Corded edge.
  3. Class Chondrichthyans.
  4. Subclass Elasmobranchs.
  5. Superorder Selakylomorphs.
  6. Orders: Squaliformes, Squantiformes, Carcharhiniformes, Heterodontiformes, Orectolobiformes, Pristiophoriformes and Lamniformes.

In the next sections we will see the most representative characteristics and species of each type of shark, differentiating them according to the 8 different orders previously described in the taxonomy of sharks , discovering the most surprising characteristics of the most curious large sharks and small sharks.

Knowing exactly how many species of sharks exist in the world is a question still unresolved by experts. The search for new species of sharks in the vast oceans is vast and complex, requiring time and effort to catalog all the physical and genetic characteristics of the species already described and those that may be new.

However, current estimates suggest that there could be between 450 and 500 species of sharks navigating the world’s sea and ocean depths, a much higher figure compared to how many species of sharks have been discovered today, which is situated in 400 species of sharks.

Squaliform sharks

Squaliforms are one of the types of sharks that arouse the greatest mystery and curiosity, due to the bioluminescence that many of the species of this order are capable of producing when they live mainly in the depths of temperate and tropical waters of the different oceans of the planet. Physically they are characterized by the presence of two dorsal fins, lacking an anal fin. They also have a total of 5 gill openings and spiracles.

Among the most representative species of this type of sharks, the one commonly known as the Pacific sleeper shark ( Somniosus pacificus ) stands out, a medium-sized species (4 meters) that inhabits the temperate waters of the Pacific at a maximum depth of 2000 meters.

More examples of squaliform species include:

  • Mielga
  • Lantern sharks
  • Cigarette tiburones
  • Sea pigs
  • I lift raspa

The most prominent characteristic of squantiniform sharks is undoubtedly their dorsoventrally flattened body, a characteristic that makes them very similar to stingrays, their closest evolutionary relatives.

The most representative species of this type or order of sharks is the Angelshark ( Squatina squatina , like the one in the image below), one of the types of sharks in Spain that have a stable population unique to Europe. Its size is less than 2 meters, and its distribution extends from the Northeast Atlantic to the Black Sea, passing through the Mediterranean Sea.

More examples of squantiform species include:

  • Angelote thorny
  • Angelfish
  • Japanese angelfish
  • Angelote africano
  • Mexican Angelfish
Carcharhiniform sharks

The most outstanding characteristic of this type of sharks is the presence of a nictitating membrane in their eyes. Their bodies are not cylindrical but rather stylized dorsoventrally, widening at the front of the head, where the snout is relatively longer than conical. Species of this order are very abundant in tropical waters , generally shallow.

Among the most representative species of the carcharhiniform type of sharks, the emblematic hammerhead shark stands out (Sphyrna mokarran, like the one in the photograph below), whose strange nose gives it one of the most surprising aspects of marine fauna. This extravagant head structure makes them one of the most advanced shark species in evolutionary terms, increasing the sensory and hydrodynamic efficiency of this species, since the brain of hammerhead sharks is more complex and sophisticated than that of other sharks. thanks to the lateral cephalic expansions that are located inside the hammer-shaped structure.

More examples of carcharhiniform species of sharks include:

  • Milbert’s shark
  • Dry Cleaners
  • Scyliorhinus
  • Musolón
  • Reaper weasel
Heterodontiform sharks

The curious order of heterodontiform sharks is characterized by being the only type of shark that does not have spines on its dorsal fins while having an anal fin at the same time, since the rest of the orders of sharks do not share these two characteristics at the same time. They are commonly known as horned sharks and are small in size, as they do not reach 2 meters in wingspan. Its distribution does not include the Atlantic Ocean, being present only in tropical waters of the Indian and Pacific Oceans.

With these interesting morphological characteristics, the Port Jackson horned shark ( Heterodontus portusjacksoni , as seen in the image below) stands out as one of the most representative species of the order. This surprising species has been the object of study in numerous scientific analyzes given their high cognitive capacity and memory, being able to learn very quickly and retain the information from the conditioning test for 40 days.

More examples of heterodontiform shark species include:

  • Suño carebado
  • Zebra horned shark
  • Galápagos horned shark
  • Japanese horned shark
  • Mexican horned shark
Hexanchiform sharks

In the order of hexanchiform sharks, we find the most primitive species of sharks , that is, those that appeared on the face of the Earth longer ago and that, therefore, present morphological and phylogenetic characteristics of greater antiquity. That is why the structure of this order of sharks is simpler, having only one dorsal fin.

For this reason, being primitive animals makes them consider living fossils , both by the scientific community regarding their genetics, and by society because of the strange and similar appearance to a living saurian that characterizes them. Fulfilling these characteristics of a primitive shark, the surprising eel shark ( Chlamydoselachus anguineus , like the example in the image below) stands out , whose strange dentition and strong jaws allow them to feed on animals as elusive as squids.

More examples of hexanchiform shark species include:

  • South African eel shark
  • Seven-gill shark
  • Snub-nosed cow shark
  • Short-nosed shark
  • Big-eyed cow shark
Orectolobiform sharks

Sharks of the order orectolobiformes are characterized by having their eyes located behind the mouth , having 5 pairs of gill slits and two spineless dorsal fins. Their snouts are short and their mouths small compared to other orders of sharks.

This order includes species with different sizes and physical morphologies, although always complying with the anatomical features common to the order described above. Among the orectolobiformes we find such well-known species as the strange catfish (genus Parascyllidae ) and the gigantic herbivorous whale shark (genus Rhincodontidae , which you can see in the image below), the latter being the largest shark in existence! Which also makes it the largest fish in the world.

More examples of orectolobiform shark species include:

  • Tiburón nodriza
  • Carpet shark
  • Zebra shark
  • Redfish
  • Blind shark
Pristiophoriform sharks

The presence of the very long saw-shaped snout is undoubtedly the defining feature of sharks of the order Pristiophoriformes, they are unmistakable! This curious characteristic gives their face / snout the appearance of a saw, which is serrated and very elongated, useful for finding and trapping their prey on the sandy bottoms of the deep sea where they live.

Among them, the long- nosed saw shark ( Pristiophorus cirratus , which you can see in this image) is one of the most representative species of the order, complying with the morphological characteristics described above, whose teeth inside the saw-shaped snout alternate in size between large and small teeth, being able to hunt both fish and mollusks.

More examples of pristiophoriform shark species include:

  • Six-gill saw shark
  • Sawtooth Shark
  • Japanese saw shark
  • Bahamian saw shark
Laminiform sharks

The most outstanding characteristic of the lamniforms is the lack of a nictitating membrane in the eyes, which are also curiously located in front of the mouth. On the other hand, the cylindrical body stands out with moderately long to very long gill slits, as well as its conical head with a short snout.

Fulfilling all these anatomical characteristics, you probably already have in mind one of the world’s best-known sharks: the fearsome white shark ( Carcharodon carcharias , like the one in this image) , whose common name is due to the white color of the shark’s ventral area. , thanks to which it camouflages itself by blending itself with the clarity of light that comes from the surfaces, taking advantage of it to surprise and quickly attack its prey. At present it is difficult to determine how many great white sharks there are in the world , since the world number is variable although a common theory is maintained: the number of white sharks population continues to decline.

More examples of lamniform shark species include:

  • Peregrine Shark
  • Marrajo
  • Zorro negro
  • Goblin shark
  • Broadmouth shark
  • Crocodile shark
Curiosities about the types of sharks

Now that we have seen in detail the main characteristics and most relevant species that belong to each of the different orders of sharks that live today, let’s see some of the most surprising curiosities of these marine animals to test how much we know about sharks .

What type of shark is the most dangerous?

Due to their skills as predators, some dangerous shark species are world famous for their attacks sometimes even on people, highlighting among them the bull shark as the most dangerous shark, because it lives in shallow waters of areas highly populated by humans, so attacks on people can be caused more frequently compared to attacks caused by other species, such as white sharks and tiger sharks, known for their aggressiveness as well. However, it should be remembered that people are not part of the diet of sharks and that attacks occur mainly, although they are not the only reasons, due to confusion, believing that they are seals or other animals that do enter their diet , or because they consider themselves in danger and seek to defend themselves.

Here you can meet the most dangerous marine animals in the world .

What is the most endangered shark?

Unfortunately, today, three-quarters of all shark species that inhabit the planet’s seas and oceans are in danger of extinction. Topping the list are such astonishing species as the oceanic whitetip shark ( Carcharhinus longimanus ) and the giant hammerhead shark ( Sphyrna mokarran ), classified as Critically Endangered species, the category of greatest threat within the list of the International Union for the Conservation of Nature (IUCN).

What famous shark names do you know?

Without a doubt, white sharks are the great stars of the cinema, appearing in such well-known films as “Jaws” and “Deep Blue Sea” , among many others. Likewise, the Submarine shark is a real white shark that is also known worldwide and there is a documentary about its history.

Types of prehistoric sharks

What were the ocean giants like millions of years ago? As we might imagine, the first sharks to inhabit the Earth were characterized by colossal size, as they competed with dinosaurs for hunting prey. Among them, the gigantic megalodon ( Carcharocles megalodon ) has been frequently studied thanks to the fossil remains found, surprising scientists with its enormous jaws and size, characteristics that it shared with other large prehistoric sharks such as the Stethacanthus Ischyrhiza

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