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Commonly known as sharks or shark, 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 large 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.
Continue reading this complete and interesting article by Ecologist Verde in which you will learn in detail all about the types of sharks, how many there are and species.
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 from starting from your taxonomy:
- Animalia Kingdom.
- Chordate Edge.
- Class Chondrichthyans.
- Subclass Elasmobranchs.
- Selakylomorphs superorder.
- 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 described previously in the shark taxonomy, discovering the most surprising characteristics of the most curious large sharks and small sharks.
How many species of sharks are there
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 in the sea and ocean depths of the world, a much higher figure compared to how many species of sharks have been discovered today, which stands at 400 species of sharks.
Squaliform sharks
Squaliformes are one of the types of sharks that arouses the greatest mystery and curiosity, due to bioluminescence that many of the species of this order are capable of producing by living 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 Pacific sleeper shark (Somniosus pacificus), 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:
- Honeydew (Squalus acanthias)
- Lantern sharks (Fam. Etmopteridae)
- Cigar sharks (Gen. Isistius)
- Sea pigs (Fam. Oxynotidae, like the one in the image below)
- Tollo raspa (Etmopterus princeps)
Squatiniform sharks
The most prominent feature of squantiniform sharks is undoubtedly their flattened body dorsoventrally, 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 Angelfish (Squatina squatina, like the one in the image below), one of the types of sharks in Spain that have a stable population unique in 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:
- Spiny angelfish (Squatina aculeata)
- Angel fish (Squatina oculata)
- Japanese angelfish (Squatina japonica)
- African angelfish (African squatina)
- Mexican angelfish (Mexican squatina)
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. The 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 (Sphyrna mokarran, like the one in the photo 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 shark species include:
- Milberto's Jaquetón (Carcharhinus plumbeus)
- Tintoreras (Prionace glauca)
- Scyliorhinus canicula)
- Musolon (Pseudotriakis microdon)
- Reaper weaselHemigaleus microstom)
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 they are small, since 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.
Counting on these interesting morphological characteristics, the port jackson horned shark (Heterodontus portusjacksoni, like those seen in the image below) as one of the most representative species of the order. This surprising species has been the object of study in numerous scientific analyzes given its 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 cabado (Heterodontus galeatu)
- Zebra horned shark (Heterodontus zebra)
- Galápagos horned shark (Heterodontus quoy)
- Japanese horned shark (Heterodontus japonicus)
- Mexican horned shark (Heterodontus mexicanus)
Hexanchiform sharks
In the order of the hexanquiform sharks we find the more primitive shark species, that is to say, those that appeared on the face of the Earth more time 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.
Therefore, being primitive animals makes them consider living fossils, both on the part of the scientific community regarding their genetics, and on the part of society because of the strange and similar appearance to a living saurian that characterizes them. Fulfilling these characteristics of primitive shark highlights the surprising eel shark (Chlamydoselachus anguineus, like the example in the image below), whose strange teeth and strong jaws allow them to feed on animals as elusive as squid.
More examples of hexanchiform shark species include:
- South African eel shark (Chlamydoselachus africana)
- Seven-gilled shark (Heptranchias pearl)
- Snub-nosed cow sharkHexanchus griseus)
- Short-nosed shark (Notorynchus cepedianus)
- Big-eyed cow sharkHexanchus nakamurai)
Orectolobiform sharks
Sharks of the order orectolobiformes are characterized by having the eyes behind the mouth, with 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 (gender Parascyllidae) and the gigantic herbivore whale shark (gender Rhincodontidae, which you can see in the image below), the latter being the larger shark that exists! Which also makes it the largest fish in the world.
More examples of orectolobiform shark species include:
- Nurse shark (Ginglymostoma cirratum)
- Carpet shark (genus Orectolobidae)
- Zebra shark (genus Stegostomatidae)
- Redfish (genus Hemiscylliidae)
- Blind shark (genus Brachaeluridae)
Pristiophoriform sharks
The presence of very long saw-shaped snout It 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 toothed and very elongated, useful for finding and catching their prey on the sandy bottoms of the deep sea in which they inhabit.
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 nose alternate in size between large and small teeth, being capable of hunting both fish like mollusks.
More examples of pristiophoriform shark species include:
- Six-gill saw shark (Pliotrema warreni)
- Tromputed saw shark (Pristiophorus cirratus)
- Japanese saw shark (Pristiophorus japonicus)
- Bahamian saw shark (Pristiophorus schroederi)
Image: Ezyjack
Lamniform sharks
The most outstanding characteristic of the lamniformes 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 best known sharks in the world: the fearsome White shark (Carcharodon carcharias, like the one in this picture), whose common name is due to the white color of the shark's ventral area, thanks to which it camouflages itself, blending itself with the clarity of light that comes from the surfaces, taking advantage of it to surprise and quickly attack its prey. It is currently difficult to determine how many white sharks are there in the worldSince the world number is variable, although a common theory is maintained: the number of the white shark population continues to decline.
More examples of lamniform shark species include:
- Basking shark (Cetorhinus maximus)
- Shark (Isurus oxyrinchus)
- Black fox (Alopias superciliosus)
- Goblin sharkMitsukurina owstoni)
- Broadmouth sharkMegachasma pelagios)
- Crocodile shark (Pseudocarcharias kamoharai)
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 species of sharks 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 in 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, at present, three quarters of all the species of sharks that inhabit the seas and oceans of the planet are in danger of extinction. Topping the list are such amazing 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 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. Also, the underwater shark It is a real white shark that is also world famous and there is a documentary about its history.
Types of prehistoric sharks
What were the ocean giants of 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 studied frequently 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. You can learn more by reading this other post about Why the megalodon shark became extinct.
If these animals fascinate you as much as we do, keep learning about them with this other post. Do sharks sleep?
If you want to read more articles similar to Types of sharks: how many there are and species, we recommend that you enter our Wild Animals category.
Bibliography- Guisande, C., Pascual, P., Baro, J., Granado, C., Acuña, A., Manjarrés, A. & Pelayo, P. (2013) Sharks, rays, chimeras, lampreys and mixinids of the Atlantic coast of the Iberian Peninsula and the Canary Islands. DiasdeSantos editions, pp: 12-30.
- Del Moral, L. F. & Pérez, G. (2013) Sharks, rays and chimeras of Mexico. CONABIO. Biodiversitas (111), 1-16.
- Drafting Team (2022). How much do you know about sharks? National Geographic Spain: Nature. Recovered from: https://www.nationalgeographic.com.es/naturaleza/cuanto-sabes-sobre-tiburones
