The Nurse Shark

  For many a species that would hold little interest, there is in fact far more to the nurse shark than meets the eye.

  Most people dismiss the nurse shark because of its evident lack of aggression. It is only to be expected, of course, that the more volatile sharks are the ones people find the most interesting. Yet those who study nurse sharks and delve into the secrets of the species find that they hold a great many surprising secrets beneath their dull exterior.

  Found in most warm waters, such as the Mediterranean Sea and West Atlantic Ocean, the nurse shark is a common sight for divers. A slow swimmer, few divers would have bargained on the nurse shark being as aggressive as it is towards humans. Although no fatalities have been recorded, this shark has perpetrated numerous unprovoked attacks to supplement the multitudes of provoked ones. Since many divers abhorrently abuse these creatures, perceiving them as weak and passive, it is most likely that those who have been attacked by nurse sharks have not recorded the occurrences for fear of persecution and humiliation. Surprisingly, nurse sharks are responsible for the most shark bites recorded.

Because of their docile nature, nurse sharks are commonly exhibited in aquariums.

  With thick skin prized above most others' as leather, nurse sharks are hunted in many areas for both their tough hide and also their liver oil, which is used in medicine. Because of its widespread population, biologists are uncertain as to the numbers of nurse sharks, although they do not believe them to be at threat of extinction.

  Feeding mostly on shellfish and crabs, nurse sharks have flat, molar-like teeth used to crush through the tough shells of their prey. For tougher-shelled creatures, however, they have a different technique: creating a vacuum with their mouths, nurse sharks are able to suck a shellfish from its casing -  rendering it defenceless and easy to eat.

  Growing up to three metres long, nurse sharks are, like the vast majority of reef dwelling sharks, nocturnal, spending most of the day resting in caves. Like many other reef sharks, nurse sharks are able to breathe without moving, by pumping water over their gills as they sit on the sand. Social creatures, nurse sharks have been known to sleep in conglomerations of up to forty specimens.

Nurse sharks normally live for about twenty five human years.

Silvertip Shark

  The silvertip shark is a magestic and sometimes scary member of the shark family. Commonly found in Northern Australia, Eastern Africa and Madagascar, the Carribean and Central American coasts, Saudi Arabia and China, it can be very territoreial and will fight to the death to keep other sharks and large, imposing sea creatures away from its territory. When it comes to hunting, however, the silvertip will not eat fish that are in its territory, but will venture from the coral reefs where they live into the open ocean which supplies them with larger, more substantial food. Silvertips are opertunistic and will take fish from fishing lines or drag them out of deep sea trawler nets by their tails.
  Although fatal shark attacks are rare, a silvertip mother will attack a human visciously if she feels they are threatening her litter, which will stay in their mother's territory until they are half-a-year old, or herself. If a human approaches a lone silvertip too quickly, the shark will become stressed and may attack. As of 2008, four provoked, and none unprovoked, silvertip attacks on humans have been confirmed-none of which were fatal-each was registered by the International Shark Attack File.
  A silvertip shark can be recognised by its distinctive silver dorsal fin tip. It is important for divers to register this when diving near one of these sharks-all but one of the attacks mentioned above were caused by the diver approaching a small silvertip under the impression it was a sluggish, harmless whitetip reef shark- the tail tips also have the silver markings.

A silvertip shark, warily guarding its territory from
competitors.