Sand tiger shark

Sand tiger sharks have a couple different names, including ragged-tooth, and gray nurse shark. These creatures are some of the fiercest looking animals in the world, with their four rows of extremely sharp teeth, and pointed snout. They have been spotted all over the world, eating mainly smaller fish, and at times, smaller sharks. The sand tiger reproduces sexually, giving birth to only two pups at a time. They are usually pretty shy creatures, and rarely attack humans. In fact, there have only been 31 sand tiger attacks from 1554 to 1996.

Anatomy
Sand tigers are one of the most vicious looking sharks in the ocean with their protruding snout and a mouth full of razor sharp teeth. The teeth will shed periodically over a two week period. The mouth can extend all the way back behind the eyes which resemble that of a cat. Contrary to the feline species, these sharks tend to have poor eye sight. Instead, they have to rely on their keen sense of smell to both navigate and find prey. Along with most sharks, they are grey colored on the dorsal side, so as when viewed from the top they will blend in with the water below. On their ventral side, they are a shade of white, so when viewed from the bottom, they will blend in with the light shining through the ocean surface. The fins give the shark a hydro-dynamic (like aerodynamic, only for the water) lift, because they are quite large and have a "fleshy" texture to them. The two dorsal fins are fairly close to each other and are about the same size. Sand tigers have a long, arching tail with a hook at the very tip. The sand tiger can attain a length of over ten feet. The interesting thing, is that they have varying personalities. Meaning that in some parts of the world they are more aggressive and are considered to be highly dangerous. While in other places they tend to be more docile and therefore are not greatly feared. 

Reproduction
Sand tigers reproduce sexually and are ovoviviparous. Meaning that they lay eggs internally (the eggs will hatch inside the mother and are then born) with live birth. They have an unusual variation of ovoviviparity which is called intrauterine cannibalism. The first of the young to reach 60 millimeters, will tear open its egg, and will swim to and start to feed on its siblings embryos. This takes place in both of the mother's two oviducts. When the pups reach about three feet long, the nine foot mother gives birth. Being this large at birth greatly increases their chances of survival, because they are already much larger than most of their potential predators. 

Ecology
Sand tiger sharks are found basically all over the world. They have been seen off the coast of Maine down to the Gulf of Mexico. They do not dwell in Caribbean waters, but are at times seen around the Bahamas. Other places include the Mediterranean, the Canary Islands, Bermuda, Argentina to Southern Brazil. These creatures' prey consists of herring, eels, mackerels, snappers, and other fish. In some unusual circumstances, they will even feed on some smaller shark species. Like most large fish in the ocean, they will undertake long migrations during certain times of the year. This is some of the reason as to why they are spotted all over the world. They will appear seasonally, within a a range of a few weeks, at the same places. These creatures are mainly nocturnal, and usually only go about 200 meters deep. This shark has a unique way of maintaining its buoyancy. It will swim to the surface and swallow air, which allows it move freely at any desired depth. These fish due somewhat to their size, are extremely strong and powerful. However they appear most often to be lethargic and slow moving. 

Social Behavior and Encounters with Humans
These creatures are usually found in large groups. They gather like this in order to mate or hunt. Research has shown that they display an obvious social behavior. They will often stay underneath overhangs of cliffs for long periods of time, due to the help of swallowed air. Even though, they have a very fearsome appearance, they are rarely dangerous. Divers will often get close to them without having to worry about being attacked. If a person approaches them too quickly, or closely they will swim about six to nine feet away and then stop. Their populations can decimate rapidly due to their shyness. People used to kill them because they looked so fierce, but today they are under protection of the law.