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Information about Sharks

[Phylum: Chordata] [Class: Chondrichthyes] [Subfamily: Elasmobranchii] [Clade: Selachimorpha]

According to the IFAW, over 500 species of sharks are currently swimming in the oceans and we can separate them into ten individual orders.

This section contains fun facts and interesting information about shark phylum, acknowledged as being the biggest predator among all fishes.

Shark Phylum and Class Explained in Detail

There are some dumb fish names in existence. But, the field of science used to classify and name this particular species is "shark taxonomy".

As such, taxonomic classification is the bedrock for shark conservation groups and in wildlife conservation.

Plus, understanding shark characteristics and behaviour is easier when there is a worldwide naming system to follow.

It's a format that marine biologists use to track how species are related and how they fit into aquatic ecosystems.

As a consequence, the methodology invented by Swedish scientist 'Carl Linneaus' in the 1600s, removes many of the previous complexities used when they named and standardised plant and animal species.

Taxonomy of a Shark

Kingdom

The grouping of all organisms consists of two major categories, animals (Kingdom Animalia) and plants (Kingdom Plantae). All shark species are animals, so they belong with the Kingdom Animalia.

Phylum

The first division of the two Kingdoms creates several smaller groupings that share similar characteristics. Sharks have a spinal cord, a notochord, and a backbone (aka vertebrae), so they belong to the phylum Chordata and the subphylum Vertebrata.

Class

Scientists classify marine vertebrates into one of the common animal groups (e.g. amphibians, birds, mammals, fish, and reptiles).

All fishes that have a skeleton made of cartilage, including sharks, belong to the Class Chondrichthyes. But, further divisions create two more subclasses, Elasmobranchii (e.g. rays, skates, and sharks) and Holocephali, soft-bodied Chimaera (e.g. ghost sharks, rat fish, and spookfish).

Order

The subclass Elasmobranchii divides into two (2) superorders for extra identification purposes. Today, we only use ten orders to identify modern sharks:

Family

Species that have close relations with other similar members of the animal Kingdom are grouped in families. So, a typical example is the Family Primates that includes apes, monkeys, and human beings.

A good example in fish is mackerel sharks. The seven families in the order Lamniformes contain the basking shark (Cetorhinidae), but there is only one (1) species. Whereas, the thresher shark (Alopiiidae), with its scythe-shaped tail, has three (3) different species.

Genus

In marine biology terminology, genus refers to the first word of the scientific name for each species. Hence, two or more species sharing the same genus shows they have some close relationship with each other.

Species

Groups of plants and animals that have the capability of producing fertile offspring, such as whale sharks with the scientific name Carcharodon carcharias, belong with that particular name for the species.

All Types of Sharks

Carcharhiniformes (ground sharks)

Atlantic Sharpnose Shark (Rhizoprionodon terraenovae)

The Atlantic sharpnose shark inhabits the subtropical waters of the western Atlantic Ocean. These requiem sharks are most common in shallow coastal zones, from New Brunswick in the north and down to the Gulf of Mexico in the south.

Common sightings occur near beaches, estuaries, and sandy bays, especially if they're swimming close to the surface above sandy and muddy bottoms.

Size, Weight, and Colour

Pups are about 30 centimetres long at birth. Even so, it's rare for adult Atlantic sharpnose sharks to grow much bigger than one metre long (4 feet) and weigh about nine (9) kilograms (20 pounds).

The identifiable feature is the slender body and a long, pointed snout. They also have distinguishing white spots scattered along the flanks.

A gray brown dorsal side slowly fades to a white underside. This kind of "countershading" provides these small sharks with some camouflage from their natural predators - larger sharks, seals, and orcas.

Eating Habits and Reproduction

Atlantic sharpnose sharks are opportunistic hunters that feed on small fish (especially menhaden), mullet, anchovies, crustaceans, and cephalopods.

Their reproductive strategies are typical of viviparous animals, meaning the young develop inside the mother and get their nourishment from a placental connection.

The gestation period usually lasts for ten months and the female typically produces between three (3) and seven (7) pups per litter.

Pro Tip: The IUCN Red List considers the conservation status of the Atlantic sharpnose shark as "Least Concern" (LC).


Bignose Shark (Carcharhinus altimus)

The bignose shark is one of the large-sized requiem sharks found in tropical and warm-temperate waters around the world.

Carcharhinus altimus flourish better along continental and insular shelves, often close to the upper continental slopes at depths ranging between 90 and 430 metres.

They are found in the deep waters near West Africa, the Mediterranean Sea, India (especially the Maldives), Australia, and Hawaii.

Size and Colouring

Even though various types of sharks have large eyes, this one also has a broad, rounded snout and elongated gill slits.

The well built and streamlined body of the adults can reach lengths close to three (3) metres, which tends to accentuate the tall first dorsal fin. They also have a smaller second dorsal positioned above the anal fin.

Bignose sharks (Carcharhinus altimus) are mostly a gray colour with a hint of bronze on the upper body. A pale underside also helps with countershading camouflage - based on a view from above or below.

Eating Habits and Reproduction

Despite being a slow-swimmer, they are a powerful predator that feeds on cephalopods (squids and octopus) and a variety of bony fishes.

Like many sharks in the family Carcharhinidae, they are viviparous. The embryos develop inside the body of the mother and get nourishment through a placental connection.

A typical litter is likely to contain between 3 and 15 pups, each one measuring around seventy (70) centimetres at birth.

Conservation Status

Its deep-water habitat generally means the bignose shark is not dangerous to humans. Still, they are sometimes caught in commercial longline fisheries for its meat, fins, and liver oil.

Pro Tip: In 2020, the International Union for Conservation of Nature listed Carcharhinus altimus as "Near Threatened" with a "Decreasing" population trend.


Blacknose Shark (Carcharhinus acronotus)

The blacknose shark (Carcharhinus acronotus) is one of the small, fast-swimming requiem sharks that inhabit the warm waters of the western Atlantic.

There is no interdorsal ridge, but they are easily recognised by the dark coloured blotch on the tip of the snout and they're often kept in large public aquariums.


Blacktip Reef Shark (Carcharhinus melanopterus)

The distinguishing features of the shark genus Carcharhinus melanopterus are the short rounded snout and the prominent black tips on the dorsal and caudal fin.

This guide contains fun and interesting facts about black tip reef sharks, including where they still exist, what they eat, and how this black-finned shark reproduces.


Blacktip Shark (Carcharhinus limbatus)


Blue Shark (Prionace glauca)

Generally they're not aggressive towards humans. But this open ocean predator shark is best known for its slender body and ultramarine blue colouring on its back.

This section contains a collection of interesting facts about blue sharks (Prionace glauca), including what they eat, where they live, and how they reproduce.


Bronze Whaler Shark (Carcharhinus brachyurus)


Brown Shyshark (Haploblepharus fuscus)


Bull Shark (Carcharhinus leucas)

In fact, the bull shark is a marine animal that is also found in brackish waters - such as the Amazon River - thousands of miles from the sea.


Caribbean Reef Shark (Carcharhinus perezi)


Catsharks (Scyliorhinidae)

There are more than 160 species of catsharks (Scyliorhinidae). They are small bottom-dwellers that belong to the largest family of sharks.

Despite being known as dogfish in some regions, the common name 'catshark' comes from the long, cat-like eyes and the slender, fusiform body shape.


Daggernose Shark (Isogomphodon oxyrhynchus)

The severe downturn in population trend is one of the primary reasons why these unique requiem sharks need our attention and better protection.

The link takes you to some essential facts about daggernose sharks (Isogomphodon oxyrhynchus), such as where they still exist, what they eat, and how they reproduce.


Dusky Shark (Carcharhinus obscurus)


Finetooth Shark (Carcharhinus isodon)


Galapagos Shark (Carcharhinus galapagensis)


Ganges Shark (Glyphis gangeticus)

Irrawaddy River Shark (Glyphis siamensis)


Great Hammerhead (Sphyrna mokarran)

Compared with other shark species, one of the genus is instantly recognised by the unconventional shape of its head - shaped like a hammer!

This segment contains fun and interesting facts about hammerhead sharks (Sphyrnidae), including where you can find them, what they eat, and how they reproduce.


Grey Reef Shark (Carcharhinus amblyrhynchos)


Houndsharks (Triakidae)

Indonesian Houndshark (Hemitriakis indroyonoi)

Ocellate Topeshark (Hemitriakis complicofasciata)

School Shark (Galeorhinus galeus)

Starry Smooth-hound (Mustelus asterias)

Striped Smooth-hound (Mustelus fasciatus)


Lemon Shark (Negaprion brevirostris)


Milk Shark (Rhizoprionodon acutus)


Nervous Shark (Carcharhinus cautus)


Oceanic Whitetip Sharks (Carcharhinus longimanus)


Pacific Sharpnose Shark (Rhizoprionodon longurio)


Pondicherry Shark (Carcharhinus hemiodon)


Puffadder Shyshark (Haploblepharus edwardsii)


Pyjama Shark (Poroderma africanum)


Sandbar Shark (Carcharhinus plumbeus)


Sand Tiger Shark (Carcharias taurus)


Scalloped Hammerhead Shark (Sphyrna lewini)


Sharptooth Lemon Shark (Negaprion acutidens)


Silky Shark (Carcharhinus falciformis)


Silvertip Shark (Carcharhinus albimarginatus)


Smooth Hammerhead (Sphyrna zygaena)


Smoothhound (Mustelus mustelus)


Sofa Shark (Pseudotriakis microdon)


Spinner Shark (Carcharhinus brevipinna)


Swell Shark (Cephaloscyllium ventriosum)


Tiger Shark (Galeocerdo cuvier)


Whitefin Swellshark (Cephaloscyllium albipinnum)


Whitetip Reef Shark (Triaenodon obesus)

It is fair to say the most distinguishing characteristics of the genus Triaenodon obesus are the grey slender body and the white-tipped dorsal and caudal fins.

Check out these fun and interesting facts about whitetip reef sharks, including where they still exist, what they eat, and how they reproduce.



Heterodontiformes (bullhead sharks)

Crested Bullhead Shark (Heterodontus galeatus)


Horn Shark (Heterodontus francisci)

Some Heterodontus francisci species actually have horns that contain venom. But, the horn shark is mostly a harmless and solitary creature that hunts at night.

The horn shark facts and information section explains where the Heterodontidae species thrive best, how their behaviour links with bullhead sharks, what they eat, and how they reproduce.



Hexanchiformes (cow sharks)

Bluntnose Sixgill Shark (Hexanchus griseus)


Broadnose Sevengill Shark (Notorynchus cepedianus)


Frilled Shark (Chlamydoselachus anguineus)


Sharpnose Sevengill Shark (Heptranchias perlo)



Lamniformes (mackerel sharks)

Basking Shark (Cetorhinus maximus)

With an open mouth measuring up to one metre wide, it's fair to say the second largest fish species might appear somewhat menacing to the uninformed.

This section contains a collection of interesting things about basking sharks (Cetorhinus maximus), such as what they eat, where they live, and how they reproduce.


Bigeye Thresher Shark (Alopias superciliosus)


Crocodile Shark (Pseudocarcharias kamoharai)


Goblin Shark (Mitsukurina owstoni)


Great White Shark (Carcharodon carcharias)


Longfin Mako Shark (Isurus paucus)


Megamouth Shark (Megachasma pelagios)


Porbeagle Shark (Lamna nasus)


Salmon Shark (Lamna ditropis)


Shortfin Mako Shark (Isurus oxyrinchus)


White Shark (Carcharodon carcharias)



Orectolobiformes (carpet sharks)

Bamboo Sharks (Hemiscylliidae)

The short pointed sensory organs (called barbels) hanging from each nostril and high set eyes are the principle biological differences that differentiate longtail carpet sharks from many of their close relatives.

Check out another section containing facts and information about bamboo sharks (Hemiscylliidae), such as where they live, what they eat, and how they reproduce.


Bluegrey Carpetshark (Geteroscyllium colcloughi)


Epaulette Shark (Hemiscyllium ocellatus)


Leopard Shark (Triakis semifasciata)

A leopard shark is instantly recognised by its leopard-like spots. The shark's yellow-brown skin tone is covered with dark brown spots.


Nurse Shark

Despite being generally harmless to humans, one of the large bottom-dwelling predatory sharks has a wide curved mouth and makes a sucking sound when it searches for food in the sand.

Check out the segment that contains fun and interesting facts about nurse sharks (Ginglymostoma cirratum), such as what they eat, where they live, and how they reproduce.

Short-tail Nurse Shark (Pseudoginglymostoma brevicaudatum)


Spotted Wobbegong (Orectolobus maculatus)


Tawny Nurse Shark (Nebrius ferrugineus)


Whale Shark (Rhincodon typus)

Whale sharks are unmistakably the largest living fish in the animal kingdom. In fact, each individual can weigh 20 metric tons and grow up to eighteen (18) metres long (60 feet).

This guide contains interesting and fun facts about whale shark species (Rhincodon typus), including where they still exist, what they eat, and how they reproduce.


Zebra Shark (Stegostoma tigrinum)



Pristiophoriformes (saw sharks)

Sawsharks (Pristiophoridae)

They are often confused with sawfish (Pristidae), which are a type of large ray fish, but sawsharks actually belong to the order Pristiophoriformes.

This section contains information about the 10 recognised sawshark species, including where they are found, what they eat, and how they reproduce.



Squaliformes (dogfish sharks)

Bramble Shark (Echinorhinus brucus)


Cookiecutter Shark (Isistius brasiliensis)


Genie's Dogfish (Squalus clarkae)


Great Lanternshark (Etmopterus princeps)


Greenland Shark (Somniosus microcephalus)


Gulper Shark (Centrophorus granulosus)

Seychelles Gulper Shark (Centrophorus seychellorum)


Japanese Roughshark (Oxynotus japonicus)


Kitefin Shark (Dalatias licha)


Ninja Lanternshark (Etmopterus benchleyi)


Pacific Sleeper Shark (Somniosus pacificus)


Pocket Shark (Mollisquama parini)


Pygmy Shark (Euprotomicrus bispinatus)


Sailfin Roughshark (Oxynotus paradoxus)


Spiny Dogfish (Squalus acanthias)


Velvet Belly Lanternshark (Etmopterus spinax)


Viper Dogfish (Trigonognathus kabeyai)

It is one of the rarest species of shark that is rarely seen by humans, but the viper dogfish actually exists - and so does its extendable jaw with razor sharp teeth.

Check out some interesting facts about viper sharks (Trigonognathus kabeyai), including where they live, what they eat, and how they reproduce.



Squatiniformes (angelsharks)

Angel Shark (Squatina squatina)

Several biological differences and unique predatory habits differentiate the common angel shark (Squatina squatina) from most other sharks.

This guide contains information and fun facts about angelsharks, including where they live, what they eat, and why some species are critically endangered.


Eastern Angelshark (Squatina albipunctata)


Japanese Angelshark (Squatina japonica)


Longnose Velvet Dogfish (Centroselachus crepidater)


Pacific Angelshark (Squatina californica)



100 Interesting Facts about Sharks

Habitat and Geographical Range

Around five hundred different shark species are still in existence today. The majority prefer to live in warm water environments, such as whale sharks.

Whereas, others thrive much better in cooler water, such as the great white shark, even at depths of 2,000 metres.

Then there are some species of shark, particularly the bull shark (Carcharhinus leucas) that are capable of living in saltwater and freshwater environments.

Whitetip Reef SharkIn general, every shark species will live in one of the following marine habitats:

  • Coral reef
  • Deep ocean
  • Estuary
  • Pelagic zone (open ocean)
  • Sandy plain

Only a few species actually fulfill their perceived role of being a solitary hunter. But in fact, most sharks live sedentary lifestyles and socialise in large schools during the mating season.

They respond to close approaches and high threat levels (e.g. when freediving with sharks) using a display of exaggerated thrashing and swim movements.

It is not unusual for pelagic sharks to roam the oceans and cover more than 1,000 miles each year. Recent reviews suggest their complex migratory patterns are similar to those in birds.

Pro Tip: Researchers and shark conservationists often use man made artificial reefs to study how nature restores itself and how new coral formations grow on the structures.

Behaviour and Characteristics

A shark is a fish that we can generally characterise using one of three groupings. The first characteristic is its cartilaginous skeleton, followed by the number of gill slits on each side of its head, and thirdly whether it has pectoral fins fused to its head.

In a process spanning thousands of years, sharks have evolved into the ultimate predators and rank among the most powerful creatures in the Blue Planet (e.g. seas and oceans).

Despite that interesting fact, or because of it, the shark phylum has a critical role to perform in oceanic and freshwater ecosystems.

For example:

Regulating the populations of other large predatory fish, such as groupers, is vital for the long term survival of coral reef habitats and sea grass.

Therefore, the underwater world needs an abundance of herbivores (plant eaters) to feed on macroalgae to stop it overpowering the reef systems.

Size and Description

Sharks are cold-blooded animals (ectothermic) with a skeleton made of cartilage and gills for respiration in water. This is the main reason why sharks are classified as cartilaginous fish (Chondrichthyes).

Excluding two species of shark, sixgill sharks and the broadnose sevengill shark, they all have five external gill slits.

The strength and flexibility of dermal denticle covering improves a shark's fusiform body shape, which also helps it resist parasitic infection.

Here's the thing:

The dwarf lantern shark, midwater shark, the dogfish, and the pygmy ribbontail catshark, are the smallest measuring less than twenty (20) centimetres in length.

Yet, the colossal whale shark is one of the biggest, measuring in at a gigantic twelve (12) metres long and weighing in excess of twenty (20) tons.

Diet and Eating Habits

Shark teeth are not anchored in the jaw, like bony vertebrate fishes, and they are able to replace the ones that fall out. In fact, some Carcharhiniformes can shed around 35,000 teeth in a single lifetime.

Most extant sharks are carnivores, which means they eat large marine animals (especially seals), squids, and sea turtles.

The rest are planktivores (e.g. basking sharks, megamouth sharks) that feed on microscopic plankton and zooplankton.

Interesting Fact: Like most cold-blooded animals, sharks have a slow metabolism and they don't eat big quantities of food (usually less than 10% of its total body weight per week).

Lifespan and Reproduction

The majority of shark species can live up to thirty (30) years of age. But, they have a very low reproductive rate.

In general, the male has external claspers on the underside of the body in front of the caudal fin. Like most vertebrate sea animals, the females tend to be larger than the males.

After mating, the exact period for gestation will depend on the different shark species. But, some females are oviparous (lay eggs), viviparous (give birth to living young), and others are ovoviviparous (eggs hatch inside the parent's body).

Shark Predators and Threats

Contrary to popular belief, sharks are not the deadliest animals to humans, not even close! Yes... There are about thirty (30) shark species that do attack people. But, it usually happens as an accident (e.g. mistaken as food) or while defending their territory.

Even so, the migratory, live-bearing requiem sharks (of the family Carcharhinidae) are involved in many of the attacks on humans. Members in the requiem shark species list include:

Recent studies suggest that about 50% of all shark species are either threatened, or near threatened, with extinction.

So, what is the biggest killer of sharks? In fact, there are many reasons for the present-day decline in most species of shark, including:

  • Commercial fisheries
  • Garbage pollution
  • Human behaviour
  • Loss of habitat
  • Overfishing
  • Slow reproduction rates

It gets even worse! The number of oceanic pelagic sharks has dropped by around 71% during the last fifty years. Official estimates of the sharks killed each year is close to 300 million (over 100 million sharks killed annually in commercial fisheries).

According to the IUCN Red List of Threatened Species, a recent assessment (February 2024) for the whale shark (Rhincodon typus) lists the species as decreasing in numbers and "Largely Depleted" (LD).

The list of endangered sharks includes the basking shark, goblin shark, hammerhead shark, and the tiger shark.

Despite this, many shark conservation groups consider their survival as being unstable and vulnerable, with some shark species being reported as "threatened with extinction".

Sharks Information and Resource Help Guides

Note: The short video [2:25 minutes] presented by "Deep Marine Scenes" contains incredible footage of the biggest fish living in the oceans today - the whale shark (Rhincodon typus).

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