You asked for it so here it is: a FOTD on the sandtiger shark!
Sandtiger sharks go by many names including the ragged-tooth shark and the gray nurse shark. When unprovoked, these sharks are fairly docile, despite their frightening appearance.
Female sandtiger sharks give birth to two live pups, one from each of their two uteri. Because of the relatively small litter size, sandtiger shark populations have a particularly slow growth rate and it takes them a long time to recover from population decreases.
When the shark pups emerge, they are about a meter in length and will grow to more than three meters by adulthood.
Sharks are negatively buoyant, which means they would sink if it weren’t for their large oil-filled livers and their constant swimming. But unlike most other sharks, sandtiger sharks often surface for air. No, they aren’t going up to breathe like marine mammals, but they swallow the air in order to better control their buoyancy in the water. Sandtiger sharks are so good at controlling their buoyancy that they can remain almost entirely motionless in the water.