What Makes Sharks So Interesting
Sharks have a reputation for being fierce, mindless killing machines – primitive, efficient and perfectly suited to hunt in the oceans of our planet.
There is a lot of truth in this. Sharks have been around for a long while and haven't changed too much in the last few million years. The shark way of living and eating has been hugely successful, and major change has been unnecessary.
A major factor in this evolutionary success story is the array of senses that help sharks find their next meal. They can detect movements in the water at a great distance, they see well and they have a great sense of smell. Some, especially hammerhead sharks, are experts at using the electricity all living things generate to work out what is happening nearby, even in total darkness.
A shark's streamlined shape and powerful musculature mean these fish are fast, too – bad news if you are a tasty fish. . . .
So this page explores a group of fish that are both primeval and sophisticated, as well as fearsome and fascinating.
The Shark List
There are well over 400 types of sharks that are usually assigned to eight separate groups. The scientific name is given in brackets:
- Mackerel Sharks (Lamniformes)
- Ground Sharks (Carcharhiniformes)
- Carpet Sharks (Orectolobiformes)
- Bullhead Sharks (Heterodontiformes)
- Angel Sharks (Squatiniformes)
- Saw Sharks (Pristiophoriformes)
- The group that includes Dogfish, Rough Sharks and Bramble Sharks (Squaliformes)
- A group of very primitive and rare sharks, such as the Frilled Shark (Hexanchiformes)
Mackerel Sharks (Lamniformes)
There are 16 kinds of Mackerel Shark in all, and they can be found in both shallow seas and deep oceans. The two things that they all have in common are large mouths and the fact they give birth to live offspring (ovoviviparous reproduction). Many other kinds of sharks lay eggs.
This group includes the notorious Great White Shark (pictured above) that occasionally terrorizes surfers along ocean coasts. Mostly, though, it preys on seals, fish, and seabirds. Its oldest fossils are around 16 million years old, so it has been a very successful animal.
The largest present-day Mackerel Shark is the basking shark which grows up to 10 meters. It is a harmless animal that filters plankton (small animals and plants) from the water.
The largest shark to ever exist was a Mackerel Shark called Megalodon. It could swallow most whales in its huge mouth. There is a size comparison drawing to the right.
A little more on Mackerel Sharks: sharkzone.com/shark-orders/lamniformes
Ground Sharks (Carcharhiniformes)
This group includes many sharks people are familiar with from movies and books. They are often reef dwellers and include the Blue Shark, Tiger Shark, Grey Reef Shark and Blacktip Reef Shark.
These Reef Shark all represent a moderate danger to swimmers and divers who are not familiar with shark habits and behavior.
There are oceanic sharks in this group, too, such as the Whitetip Sharks. Whitetip Sharks are just about the last animal you want to meet in open waters after a boat or plane wreck. They are slow-moving but very aggressive and large enough to tackle any survivors.
The very distinctive Hammerhead Sharks are also Ground Sharks. Many species like to live along coastlines.
Carpet Sharks (Orectolobiformes)
The carpet sharks include the largest known fish, the massive Whale Shark. This can be as long as 10 meters. Fortunately, it is a peaceful animal that filters tiny plants and animals from seawater as it swims along with its mouth wide open.
Other carpet sharks include the very beautiful Wobbegong (pictured above), which are popular in large aquariums.
More on the biology of Carpet Sharks: elasmo-research.org orectolobiformes.htm
Bullhead or Horned Sharks (Heterodontiformes)
This order is a group of sharks that have adapted to living off crustaceans, sea urchins and mollusks on reefs in warm oceans.
They have big heads and large brows. The groove that runs from nostrils to mouth makes them look surprisingly cow-like. They can seem clumsy and even comical when compared to other groups of sharks, but they are successful animals.
Angel Sharks (Squatiniformes)
This group has species that are flattened like rays or plaice. This is an ideal adaptation for living on the bottom of the sea in sandy places. It is easy for a Carpet Shark to bury itself in sand and wait for a good meal to come along. Then, in a flash, the fish can throw off the sand and grab its prey.
The Angel Shark pictured above has a skin coloring that provides excellent camouflage. It would not even need to bury itself to be very hard to spot.
The Pacific Angel Shark (Squatina californica) is a relatively common Angel Shark living around the kelp forests off the coast of California and eating small fish and squid. It is quite small but can give people a nasty bite if it feels threatened.
Saw Sharks (Pristiophoriformes)
These often have a long snout with plenty of teeth they can use to slash their prey. They can look like fish with a chainsaw attached to their head. Fortunately, they are quite small – usually no more than a meter in length but sometimes close to two meters.
They eat small fish, squid, and crustaceans.
They are at home in the Pacific, the Atlantic, and the Indian Oceans. In cooler regions, they are found in shallow water. In warm water, they venture deeper.
An unusual feature is that they give birth to live young.
There is some additional information here: http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/375935/Sawsharks.pdf
Squaliformes: the Dogfish Sharks, Bramble Sharks, and Rough Sharks
This includes the common but tiny Lantern Shark that sports fishermen often catch. It usually grows to about six inches long.
The group also includes the Dogfish Sharks, which are also common. There are some large species like the Greenland and Pacific sleeper sharks, which can grow to eight meters in length.
In days gone by, sailors used small Dogfish to scrub wooden decks clean. Sharks have very tough skin covered in tiny teeth-like structures called denticles. Apparently, they made excellent abrasive pads.
We hope no one abuses these creatures in this way nowadays!
Bramble Sharks can grow up to three meters. Rough Sharks are generally smaller at less than two meters. Both kinds of sharks tend to live on the bottom of shallow seas and eat invertebrates.
More on Dogfish, Rough Sharks and Bramble Sharks: pbs.org/squaliformes.html
This is a primitive group that has been on this planet since the time of the dinosaurs. The group includes the Cow Sharks and the Frilled Shark.
The Frilled Shark in the video above may not look like the shark in Jaws but certainly has some attitude.
Fishing, Conservation and Sharks
Modern fishing methods are now so effective that large areas of the sea can be swept clean of all fish life by a factory fishing vessel.
Most sharks are not fished for food but are often caught along with other fish. Some sharks are fished only for their fins (shark fins are used in soup in Chinese cooking).
Many kinds of sharks have become rare, and some are threatened with extinction. Find out more here: guardian.conservation.aaas
Genevieve on July 20, 2020:
I love all kinds of sea life!
rahul reddy on January 03, 2020:
amazing picture of shark
Will Apse (author) on November 15, 2019:
You should write an article. Sharks are fascinating creatures.
person on November 14, 2019:
there should be way more sharks then that even i know more sharks like the thresher shark or even the most known the blue shark.
i knew more than all of those
blah blah blah on January 14, 2019:
Really good lots of sharks. If you could add more sharks and info that would be great! ^-^ Thanks!!
angiluo on June 03, 2018:
what shark is very long
Marissa on May 07, 2018:
what is the most dagerouse shark.whitch is the longest shark.Can u put on more sharks?
Stormy on April 13, 2018:
those sharks are sooooooo cool! One question...... which shark is the most dangerous shark thats alive?
peachy from Home Sweet Home on June 01, 2013:
A worth to bite hub! Do you know the name of a shark that eats only plankton, non-meat eater? I saw the information in an encyclopedia once but can't remember the shark's name. Great hub and lots of information, photos that you could form into an e-book!!! Voted up
tom hellert from home on September 26, 2011:
Awesome- but I didn't see a mention of the Bull Shark-the most dangerous shark unless I missed it. but-I might have missed it-great job either way...
Will Apse (author) on September 23, 2011:
Thanks, Beast! I actually like to know that there at least a few species of animals living lives undisturbed by human beings. It would be nice to take peek at them, though.
thebeast02 from Louisiana on September 21, 2011:
Awesome hub! Sharks are so intriguing. The fact that they are still finding some extremely exotic species leads me to believe that there is still so much more to be found in our deep oceans. I just hope that I'm around by the time we can reach those depths.
Dallas W Thompson from Bakersfield, CA on September 16, 2011:
Great photos with lots of information. Thanks for the article! Flag up!