(Image credit: Flickr user Gore Fiendus/Jerry Frausto)There are seven known species of sawsharks (Pristiophoriformes) that have long snouts with teeth, but they are not related to sawfish (although sawsharks are fish). They swim along the floor of the ocean and use their snouts exactly as you would imagine: they smack their prey sideways to disable them. Sawsharks eat squid, crustaceans, and small fish. They look much more dangerous than they are.
2. Basking Shark
The basking shark (Cetorhinus maximus) is the second-largest of all living shark species, with only the whale shark growing larger. They normally grow to 20-26 feet long, with the biggest confirmed specimen measuring over 40 feet long! They have mouths up to three feet wide, which they hold open while swimming. That's because they are filter feeders that scoop up plankton, crustaceans, and small fish as they swim.
(Image credit: Flickr user David Biesack)There are eight or nine different species of hammerhead sharks (Sphyrna), named for their unusual shape. The reason behind the peculiar shape of the shark's head was debated for many years. Scientists speculated that the distance between the shark's eye gave it some kind of advantage. Recent research confirms this. Hammerhead sharks can see a range of 360 degrees vertically. They can easy see behind them with a slight turn of the head, and most importantly, their two eyes have a huge overlap of field compared to other sharks, indicating they have excellent binocular vision. Hammerhead sharks are able to judge distances well by sight alone. They also differ from other sharks in that they tend to swim in schools and they can develop a tan when exposed to sunlight.
4. Megamouth Shark
Is there a more descriptive name for any animal than a megamouth shark? The megamouth (Megachasma pelagios) was first discovered in 1976. It is a filter feeder with very small teeth, but swims with its huge mouth open to scoop up jellyfish and plankton. The megamouth shark is a rare creature and is rarely seen. There have been only 41 confirmed sightings, including one last year in which a megamouth was caught and eaten by fishermen in the Philippines. See a video of a live megamouth at YouTube.
5. Thresher Shark
The thresher shark (Alopiidae) is most notable because of its long upper caudal (tail) fin which may account for half the shark's total length. The thresher shark eats small fish, and will sometimes tap the water with its tail to herd schools of fish into tight spots, making them easier to eat. They can also use their tails to stun their prey with a good smack. Thresher sharks are usually 10-15 feet long, and can grow up to 20 feet long -but remember, about half of that length is tail fin.
6. Frilled Shark
The frilled shark (Chlamydoselachus anguineus) comes very close to our image of a sea serpent from ancient lore. These sharks are not particularly large at about six feet long with a slender body, but they are very flexible and can move in a rather un-sharklike way. When the shark flares its neck frill, it can look quite menacing. However, they are rarely seen by humans as they prefer to hunt in deep ocean depths.
7. Cookie Cutter Shark
The cookie cutter shark (Isistius brasiliensis) got that strange name from its habit of biting chunks of flesh from its prey by wrenching its body around in a circular motion after sinking its teeth into a fish too big to eat whole. Ouch! The cookie cutter shark reaches only around twenty inches in length, but has been known to bite into whales, submarines, and people. It has a small bioluminescent patch that fools other creatures into thinking it is a much smaller fish than it really is while the rest of the cookie cutter fish waits in the dark.
8. Goblin Shark
The goblin shark (Mitsukurina owstoni) is a deep water species that is rarely seen by humans. It is believed to be an ancient species even by shark standards. It has an unusually long snout, which you'd think would make it hard for this shark to eat, except that the goblin shark has one strange feature to compensate. It has jaws that can protrude out of its face, like the alien in the movie Alien.
If you think that may give you nightmares, just keep telling yourself that goblin sharks live way too deep to be a threat to humans.
9. Whorl Shark
Shark fossils show that weird sharks are not just a modern development. Although we know little about it, the whorl shark (Helicoprion) is a truly strange fish that lived 280-225 million years ago. The whorl shark's distinction is a spiral of teeth it left behind. Modern sharks continue to grow teeth throughout their lives and shed old teeth. Ancient sharks grew new teeth, but kept the old teeth as well. In some species, old teeth migrated to the face to make room for teeth in the jaw. In the whorl shark, old teeth were just rotated around. But where in the shark were these teeth? Full fossils have not yet been found, so some scientists believe the spiral teeth were in the front of lower jaw as shown here. Others believe the spirals were in the shark's throat like an internal circular saw, as you can see in this recreation.
(Image credit: Flickr user Steve Flamingo)As far as we know, megalodon (Carcharocles megalodon) was the biggest shark that ever existed. It grew up to 60 feet long and consumed over a ton of food every day. The word megalodon means "big tooth", appropriate as the megalodon had a bite more powerful than a T. rex, which it used to eat whales. Megalodon lived 25 to one million years ago, although it survives today in film and in our nightmares.
These weird sharks are listed in no particular order. Which do you think is the weirdest?