The Whitetip Reef Shark

  Predominantly inhabiting the Indian and Pacific Oceans, especially the Great Barrier Reef, where it is one of the most common sharks, whitetip reef sharks could be referred to as the wolves of the sea - dominating the ocean at night and swarming across reefs in their hundreds.

  Small and slow, whitetip reef sharks make for good aquarium exhibits and are a great attraction for divers in the wild. Although they are generally passive, these reef sharks have been known to attack spear-fishermen whilst trying to steal their catch. Numerous divers have been injured in the feeding frenzies that ensue, although these well-publicised events are few and far between.

  Dwelling in caves for the most part of the time, whitetips come to life at night as they prowl their reef-homes in the dark - preying on any unfortunate fish or crustacean they come across. With slender, cartilaginous bodies, they can easily press themselves into crevices or caves in search of food. Scavengers by nature, some whitetip reef sharks - most notably those of Hawaii - have learned to follow seals in order to steal their hard-earned meals. Others have developed the bait of waiting by reef drop-offs and catching the remains of fish,

Whitetip reef sharks rarely grow
to two metres in length.

which float in with the tide.

  A typical behaviour of reef sharks, whitetips often frequent cleaning stations on their reef, where cleaner wrasse and small fish feed on the many parasites sharks are known to suffer from. Copepods often attach themselves to whitetips in order to feed on their flesh.

  Their are, however, some more fearsome predators to the whitetip reef shark. Around America and Mexico, tiger sharks frequently kill whitetips for their meat, while silvertip sharks in Australia will attack any creature in order to defend their territory. Astonishingly, the remains of full grown whitetip reef sharks have been discovered in the stomachs of giant groupers. These gargantuan fish often inhabit the wreckages of boats and aeroplanes near to reefs and are easily capable of swallowing a shark whole. Due to their rarity, however, such an occurrence is not common and has only been witnessed a few times.

  Rarely leaving the reef they were born at, whitetip reef sharks have come to symbolise fidelity to the natives of many Pacific islands. This is generally attributed to their fear of the predators around their reefs, rather than to the sharks being instinctively territorial, as they are social creatures and often rest in large groups during the day.

  Sadly, whitetip numbers have declined in recent years due to the numerous fisheries hunting them for the hide, meat and liver oil. The destruction of their restricted reef-habitat has also played a large role in this, reducing their numbers abhorrently. Slow reproducers, it is quite possible that whitetips will be hunted to extinction in certain areas before they are able to repopulate.

A juvenile whitetip reef shark on the Great Barrier Reef. Note the distinctive
white fin and tail tips.

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.

The Epaulette Shark

  Not to be underestimated on account of its size, nor because of its passive aura, the epaulette shark has adapted perfectly to its environment and is an ideal demonstration of evolutionary genius.

  Exclusively inhabiting the tidal waters of the Great Barrier Reef, the epaulette shark is often seen by reef divers as it stows away in crevices. A small shark even by reef standards, most epaulettes only grow to around one metre in length and would be at the mercy of luck if confronted by the larger blacktip reef and silvertip sharks which prowl its coral-coated home.

  However, whilst it might be a cowering creature whilst the water is deep and dangerous, when the tide is out and the reef reduced to a mere collection of rock pools, this shark transforms into the indisputable overlord of the environment - a merciless, unpredictable hunter.

  Feeding mostly on crabs and small fish, the epaulette is perfectly suited to life among the rock pools. Its small and cartilaginous body allows it to work its way into the smallest of caves and under the lowest of overhangs in search of prey.

  Whilst its prey are unable to escape the pools in which they are enclosed, the shark itself has the abnormal ability to leave the water and move across dry land, using its small, sturdy fins as legs. Most fish die relatively quickly after emerging from their subaqueous empire, but the epaulette shark, on the other hand - or fin, as the case may be - is able to survive without oxygen for sixty hours longer than a human being by shutting down its internal organs. This queer capability gives the epaulette shark a vital advantage as a hunter, especially considering it has so little time to find a meal before the waters flood back in and it must once again return to its life of concealment from its predacious cousins.

  Commonly seen in aquariums, epaulette sharks are not dangerous to humans. Even when handled they are generally passive, although they have been known to ocationally bite provocateurs - a behaviour that can only be considered natural.

One of the epaulette shark's key
defences is its camouflage.

Despite its unimposing nature, the epaulette shark is an
accomplished hunter.

Because its body is soft, the epaulette
shark can easily squeeze through small
gaps.

Apologies

All,

I must apologise for my lack of activity on this blog over the past months. I won't elaborate as to my reasons for this as they were many, however, I promise you that more posts will be coming your way over the coming weeks.

Keep reading and keep learning about sharks.

Daniel Bailey