Shark Attacks - Man-eating Sharks » Oceans and Environment
As with any other article on shark attacks I’ll start by mentioning the statistical improbability of ever being attacked by a shark. Over recent years there have been an average of 60 shark attacks a year ,a number which is declining annually. Out of these only about 15-20% proved fatal. So in short there is more likelihood of being killed by lightning or the family dog.
However, it is a primeval fear that sharks strike into the hearts of many. The idea of being eaten alive by a monster fish has few equals in the21st century World. This has been exacerbated by a number of films and the media feeding frenzy (excuse the pun!) around any shark attack that happens.
There are around 400 species of shark in the World’s oceans yet it is only a tiny fraction of these that are considered dangerous to man. Below are some details on the most infamous and commonly implicated of these oceanic predators.
Great White Shark (Carcharodon carcharias)
More fatal shark attacks have been attributed to the great white than most other species added together. The white shark is indeed a fearsome predator reaching over 6 metres (20 feet) in length and weighing up to 1,900 Kg (4,200 lb).
Great whites are actually warm blooded which allows them to inhabit cooler waters than was previously thought and they can indeed be found far and wide. With this adaptation comes a huge appetite and common prey includes seals, porpoises, tuna and even other sharks. Humans are not however a meal of choice. There is some debate over why great whites attack humans. Some sources suggest mistaken identity with the shark believing the silhouette it sees on the surface is a seal. Another possibility is ‘test-biting’ in which the shark mouths an object to determine what it is.
Either way it is probably of little consolation to the victim that great whites don’t actually seem to like humans as a meal! In most attacks the victim has been left uneaten and the cause of death has been blood loss. It is thought us humans are too boney and without enough meat for the great white’s palate.
Great white shark attacks on surfers »
Tiger Shark (Galeocerdo cuvier)
Sometimes referred to as the garbage can of the ocean due to their indiscriminate appetite the tiger shark is second only to the great white in numbers of attacks. Tiger sharks can reach up to 4.25m (14 ft) and weight up to 909 kg (2000 lb) and are found throughout the tropical and temperate regions of the World’s oceans. Combine these factors with the shark’s aggressive nature and the fact that it coexists in close proximity to many populous areas and you can figure out how the tiger earned its reputation.
Tiger sharks often hunt at night or in murky waters using low frequency pressure receptors although they also have excellent vision and an acute sense of smell. They are also known to feed around rivermouths.
Unlike white sharks, tigers are likely to consume all their prey during the attack and worry about what it is later! Objects such as number plates, tin cans, tires and baseballs have all been found in the digestive tracts of tiger sharks
Tiger shark attacks on surfers »
Bull Shark (Carcharhinus leucas)
Coming in third place in the fatal shark attack stakes is the Bull shark. This common shark is known by various names around the World including the Zambezi, Ganges, Nicaragua, river, Swan River Whaler, cub, shovelnose, bull whaler, Fitzroy Creek whaler, square-nose, and Van Rooyen’s to mention a few.
As you may have guessed from this list the bull shark can tolerate fresh water. They can travel thousands of miles up rivers and have been responsible for many attacks far from the sea. There are several populations of Bull sharks in freshwater lakes around the world
The sharks are named after their short snout which is wider than it is long. They can grow to 3.5 metres (11 ft) in length and weigh up to 318 kg (700 lb) with the female about twice the size of the male. They are highly territorial and will attack other species that encroach on their territory, including humans. This aggression towards humans has been recorded in clear conditions and when the sharks have not previously been agitated
Bull shark attacks on surfers »
Oceanic Whitetip Shark (Carcharhinus longimanus)
The oceanic whitetip is a deep water shark which has been responsible for more attacks on humans than all the other species put together. The reason for this is has often preyed on the survivors of oceanic shipwrecks and downed aircraft. It is therefore of little danger to the average surfer and just in the list for interest’s sake.
The whitetip grows up to around 4 metres (13ft) and weighs up to 170Kg (370lbs). It has large rounded fins with white tips and slowly cruises the open ocean on the lookout for food. Although generally slow, the whitetip is capable of bursts of speed and can be highly aggressive - often manifesting itself in feeding frenzies.
Oceanic whitetip numbers are in decline. Pressure from fishing and the fact that its large fins are highly valued as the chief ingredient of shark fin soup has put the shark on the vulnerable species list
Hammerhead Shark (Sphyrna mokarran)
Statistically speaking the hammerhead is the 7th most dangerous shark although this only equates to 33 non-fatal attacks in 500 years. There are nine species of hammerhead so called because of their distinctive head shape. There is some degree of doubt over which particular species has been responsible for the attacks as they are relatively hard to tell apart. Therefore as the biggest of the bunch (up to 6 metres / 20ft) the great hammerhead shark (Sphyrna mokarran) has been attributed the blame!
The strangely shaped head was originally thought to aid in maneuverability but it is now though to aid in sensing prey by creating larger nasal tracts and also spacing the sensory organs further apart to improve directional detection.
Other strange facts about hammerheads is they are able to reproduce asexually and they are one of the few animals that can get a sun tan!
