Shark

Sharks are known especially by a cartilaginous skeleton.

Sharks make up a family of elasmobranch fishes. They also have about five to seven slits at the side of their head for their gills. Their pectoral fins are not fused to their heads.

Experts believe that there are about 400 species that form about 14 to 30 shark families. Some of the common species include the salmon, tiger, great white, whale, and bull sharks.

Incredible Shark Facts!

• Boneless creatures: Sharks are fish that do not have any bones at all. Instead, their body is primarily made of cartilage instead, which is the same material that the human nose and ears are made from.
• Good eyesight: They have pretty good eyesight which means that they can also see clearly in dim-lighted areas.
• Sandpaper texture: The skin of these fishes often feels like sandpaper. This is because their skin has small teeth-like structures.
• Immobility trance: These fishes can become immobile when flipped upside down.
• Ancient fishes: Sharks are ancient fish and scientists believe that these fishes have been around for more than 450 million years ago.
• Land sharks: One species of shark — the epaulette shark — has evolved the ability to walk on land over small distances!
• Sixth Sense: Sharks have long been thought to have a sixth sense.

Shark Classification and Scientific Name

These fishes go by the scientific name Selachimorpha. These fishes belong to the kingdom Animalia and phylum Chordata. Their class is on Chondrichthyes.

Selachimorpha comes from a combination of Ancient Greek words – sélakhos and the suffix -morpha. Sélakhos means “cartilaginous fish.” However, the word can be broken down even further to the root “sélas,” which means “light” or “glow.” These pre-Greek origins are likely due to the phosphorescent light that some of these sharks have.

Beneath the Selachimorpha superorder, there are 8 orders that are still alive, which include squatiniformes, pristiophoriformes, squaliformes, carcharhiniformes, lamniformes, orectolobiformes, heterodontiformes, and hexanchiformes. Four orders of these fishes have gone extinct, but there are still over 470 different species alive today.

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Shark Species

With over 470 living species of sharks, the scientific name for this superorder is Selachimorpha. Even with four different orders extinct, the fish still manages to have quite a few variations. Some of these species have no anal fin, while others do. Everything from the positioning of the mouth to the length of their snout can differentiate between other species.

Some of the most notable types of sharks include:

• Great white shark: Perhaps the most popular and well-known, the Great White is the largest species in the ocean, and it can reach lengths of about 20 feet. Plus, these fish can reside in the ocean for 30 years, swimming along coastal waters.
• Cookiecutter Shark: The cookiecutter shark takes its name because it leaves a cookie-shaped bite hole in its predators. These sharks have the largest teeth of any shark species at any location. Like all sharks, it loses its teeth and grows new ones throughout its life.
• Ragged tooth shark: These sharks stand out for an interesting reason – it gulps air. Much like a mammal would, this species will hold onto the air in its stomach so that it can stay in the same place. Their dagger-like teeth are lined along two rows on both their top and bottom jaw, though they actually lose up to three teeth daily. Even with their ferocious appearance, they are fairly harmless if left alone.
• Bull shark: Primarily residing in freshwater areas, the bull shark will seek out shallow areas. They have special glands that provide them with the salt that their body needs, allowing them to journey where they need to go for food.
• Tiger shark: These sharks can grow as long as 18 feet, and they are pretty easy to identify with their vertical stripes and spots. They will live in both shallow and deep waters, and their jaws are powerful enough to break apart the shell of a sea turtle.
• Salmon shark: Salmon sharks can be very dangerous to humans. At about 6.5 feet long (at their shortest), they typically live in the northern region of the Pacific Ocean. They are able to regulate their own stomach temperature, though this feature is rare amongst sharks in general.
• Nurse Shark: These sharks don’t pose any threat to humans unless they are disturbed. In fact, many people swim right by these sharks without ever knowing they were there.
• Horn Shark: The horn shark moves by pushing itself along the bottom with its strong fins. This shark is very sensitive to light. It spends almost all its life hidden in crevices, shadows, or dark waters.
• Goblin Shark: The Goblin Shark, which is sometimes referred to as a living fossil, is a type of shark that is found in the deep sea. This unique-looking shark is easily identified by its long snout, protruding jaws, and semitranslucent skin. Goblin Sharks have been found in all three of the major oceans. Because they live so deep under the water, there are still a lot of unknowns about this creature.
• Greenland Shark: This shark has the longest lifespan of any vertebrate. The Greenland shark, called eqalussuaq by the Inuit people is famous for living to a great age. Biologists believe that this large, slow fish can live to be half a millennia old. Its longevity probably has something to do with the fact that it does everything slowly. It swims slowly. It reproduces slowly. It catches prey by sneaking up on them when they’re asleep then attacking.
• Grey Reef Shark: Grey reef sharks are voracious marine predators that prefer shallow waters and are among the most common sharks found in coral reef habitats throughout the Indo-Pacific region.
• Basking Shark: These sharks tend to swim with their big mouth hanging wide open, which can be intimidating to divers who don’t know better.
• Hammerhead Shark: Hammerhead sharks are best known for their long, rectangular heads. They tend to swim at an angle to decrease drag and increase their swimming efficiency.
• Frilled Shark: Frilled Sharks got their name from the six rows of gills on their throat that look like ruffled collars.

Shark Appearance

These fish have a cylindrical shape and have tapered edges. This body structure allows them to smoothly sail through deep waters in search of their prey. However, the length of their body and even their snout can be different from species to species.

Sharks are usually 5.8 to 7 meters long – which is at least 3 times the height of the average human. While the smallest species are less than 20 centimeters long, the largest one is about 12 meters. Sharks usually have a bodyweight of around 1500 to 4000 pounds. However, some can also weigh about 5500 pounds.

These fish are naturally colored to be able to camouflage and blend with their surroundings – typically to catch the prey easily. The dorsal side of their body is darker than the ventricle side. Therefore, when seen from above, the body of the shark would usually blend with the dark atmosphere of the ocean.

Shark Distribution, Population, and Habitat

Sharks, along with their sister group of rays have, over millions of years, adapted to living in a wide range of habitats. While some of them live in shallow and coastal regions, others live in deep waters. Some others are further found in the open oceans or the ocean floors.

Even though these large fishes are found in several places around the world, they are mostly and most commonly found in the USA and Australia. There are only a few species (i.e., the bull shark and the river shark) that live in freshwater areas, but the highest number are found in the waters of New South Wales in Australia. They can also be found in the Indian Ocean, near Brazil, and even as local as North Carolina.

According to experts, there are more than 400 living species of these fish around the world – all of which are divided into 14 to 30 different shark families.

Shark Predators and Prey

As big as these fish may be, most people believe that this fish has no natural predators, but they would be incorrect. Both killer whales and sperm whales will consume smaller shark breeds as their nourishment, but they consume their fair share of animals in the sea as well.

What Sharks Eat

Sharks have no qualms consuming their relatives, as larger sharks will consume other species as well. All of them are carnivores, which means that they will only eat other animals as their nourishment. Most sharks enjoy a balanced diet of dolphins, seals, turtles, and even seagulls. They seek out other fish and sea mammals as well.

What Eats Sharks

As stated above, these fish have the threat of other sharks coming after them as food. Apart from their own species, the amount of fat and protein that they offer make them ideal for the diet of an orca whale or a sperm whale. In fact, these orcas, also known as killer whales, are apex predators, and even the largest sharks cannot hunt them.

Shark Reproduction and Lifespan

These fish do not reproduce like the other fishes. They use internal reproduction as a method to produce babies, much in the same way that mammals do. The male has two organs that are attached to their anal fins for the purpose of reproduction.

When mating, the males insert one of them into the female’s cloaca. During the insertion, the sperm is transferred from the male to the female. The sperm then fertilizes the egg inside the female.

Though the exact amount might vary by the species, this fish is famous for its long pregnancy, which lasts for an average of a year. However, some sharks have as little as a 5-month gestation period, while others may gestate for three long years.

The lifespan of sharks is about 20 to 30 years.

Shark in Fishing and Cooking

Most of these fishes are fished out for commercial purposes. They are cooked widely, especially in the United States. Due to their body weight, they are a good meat source for humans.

People love eating shark steaks which are prepared using a wide variety of spices and are later cooked in oil before being savored by several humans.

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