Since i was once 1m away from a big raggie during a dive, something i will never ever forget, i think it is appropriate to give some info on them
This large coastal species of shark occur in most subtropical and temperate oceans.
They are also known as the Sandtiger shark and the Grey Nurse although the different populations never meet up due to geographical distribution.
They are generally coastal, usually found from the surf zone down to depths of around 25m.
However, they may also occasionally be found in shallow bays, around coral reefs and, very rarely, to depths of around 200m on the continental shelf.
They usually live near the bottom, but may also be found throughout the water column.
They swim slowly with their mouths open, exposing a permanent toothy grin that reveals dagger-like, narrow double-edged teeth making it appear ferocious (
trust me it does!!!)
In most sharks the teeth are only exposed when the shark opens its mouth.
Despite their menacing looks raggies, as they are affectionately known in South Africa, are considered docile.
No human remains have ever been found in a ragged tooth shark and there is also no scientific evidence that they will attack humans unless provoked.
Instead they feed on a wide range of fish, smaller sharks, squids, rays and lobster.
They have a number of characteristics and behavioural patterns which make them markedly different to other sharks.
In particular, schools of ragged tooth sharks (which can number up to 80 off the South African coast) have been observed to feed cooperatively, marine scientists report rare sightings of watching raggies work together to bunch up food and then eat it collectively.
The teeth of the ragged tooth shark are very different to those of the white shark.
Raggies' teeth are sharp, round and curved and are designed to hold their prey while they swallow it whole. The white shark, on the other hand, has sharp, heavy, triangular teeth for cutting their prey, such as seals, firstly to kill them and then to reduce the carcass to manageable pieces.
Raggies cannot swallow whole fish tail first as the fish's dorsal fins catch in the shark's throat.
Therefore, when a raggie catches a fish from the tail end it must work it around in its mouth until it can safely be swallowed head first.
This is done using a series of quick snapping movements as the raggie dare not drop its prize for fear of it being grabbed by another prowling raggie.
While doing this, the raggie's jaws are extended forward with their teeth protruding, a very scary sight when you are only centimetres from the action.
Most large sharks are committed to a life of perpetual motion so that oxygenated water passes over the gills.
The raggie is one of the few large sharks capable of remaining stationary and actively pumping water over the gills.
This is how come 40% survive the shark nets.
If left too long however they too drown.
The ability they have to pump water over their gills reduces the energy spent in swimming and enables the shark to remain motionless in the water column.
This in itself gives rise to another problem: sharks are negatively buoyant and lack the swim bladder found in bony fish that helps to maintain position.
The raggie has a neat answer to the problem; it ventures to the surface to swallow air that is then retained in the stomach thereby simulating a swim bladder.