Although rare, it is certainly not unheard of for humans to be attacked by aquatic animals. The question is, what marine species of animal is most dangerous to us humans?

Sharks will continuously come up on simple Google searches of deadly marine animals, as well as in books, surveys and documentaries. The chances of being attacked by a shark are one in 1.5 million (ISAF). Even though the odds are very little, the public are lead to believe that the main cause of these rare attacks are mainly because of the Great White Shark (Carcharodon carcharias). This is down to a number of movies about unrealistic shark attacks and a large amount of attention the media gives sharks, such as Shark Week on the Discovery Channel. However, sharks are not the only animals around the coast line that prove to be a threat to humans. In some places around the world, such as Australia, Southeast Asia and eastern India, similar locations to where white sharks are found, there are other active and dangerous animals in the water and around the waters edge, such as the Saltwater Crocodile (Crocodylus porosus), the largest reptile in the world.

An advantage that the Saltwater Crocodile has that the Great White Shark does not is that the Saltwater Crocodile can inhabit the land as well as water, increasing the chances of human interaction. Although not strictly aquatic, the Saltwater Crocodile will spend its time waiting in the shallow waters of rivers and waterholes, waiting for prey to come to the edge. When given the opportune moment, the crocodile will grab its prey from the shoreline and drag it underwater, drowning it. The average size of Saltwater Crocodiles to be recorded is between 3 to 4m  however, individuals have been found to be seven metres long, proving why the Saltwater Crocodile is the largest reptile in the world (Ryan, 1998).

Figure 2. shows a recording of numbers of Saltwater Crocodile attacks in different conditions. The table states that 76.7% of nonfatal attacks were during the day and 23.3% of nonfatal attacks were at night. This would suggest that the crocodiles were more likely to attack during the day, also when most humans are active, leading to an increase of chances of interaction between both. However, Fig.2. also shows that 50% of fatal attacks were during the day and the other 50% during the night. This shows that a Saltwater Crocodile’s behaviour is somewhat unpredictable and would attack unprovoked at any time of day. Although it has to be taken into consideration that some cases shown on Fig.2 are listed as unknown time of day. (Caldicott, 2005). Their unpredictable behaviour allows them to surprise their prey when hunting. It is also this behaviour which leads to attacks on humans and makes them contenders for being one of the most dangerous animals to humans. Similarly, Great white sharks have hunting techniques to surprise their prey, their dark grey colouring on their dorsal side allows them to blend in with the rocks on the seabed, while their white ventral side camouflages them from underneath to blend in with the surface of the water as the light reaches it (Peschak et.al 2006).

Great White sharks, the largest predatory fish, have been recorded to grow to six meters long (Bruce et.al, 2006), smaller than recorded saltwater crocodiles. This alone could intimidate a human due to the average size comparison. Steven Spielbergs’ 1975 film ‘Jaws’ was an interpretation of Peter Benchleys’ novel with the same title published in 1974, a story about a great white shark found to be hunting humans in a popular holiday destination. This has created a misconception about Great White Sharks, that they will prey on every human they come across. Found across the world nearing to warmer climates and the equator, Great White Sharks can be seen closer to the shore rather than out in the ocean in order to find prey (Last & Stevens 2009). This mimics Benchleys’ behaviour of the Great White Shark coming into human civilizations such as shores however, the odds mentioned above conclude that Great White Sharks do not actively prey on humans like in Benchleys’ novel.

Records show that there have been approximately 279 White Shark attacks on humans since 1580, 78 of these attacks have been recorded as fatal (ISAF). This can be seen in Figure 3. This same record, created by the Florida Museum of Natural History, University of Florida, shows that the majority of shark attacks recorded have been from White Sharks. Although, when compared to other species of sharks, the White Shark looks to be the most deadly to humans, the witnesses and victims of the attacks could easily mistake the species of shark, assuming that it is a Great White Shark because of the nature they have been perceived to show.  It is less likely that another species of crocodile would be mistaken for a Saltwater Crocodile when attacking due to the area they populate and their size, making witness appeals and records of attacks more reliable than White Shark attacks.

Both species of animalia, the Great White shark (Carcharodon carcharias) and the Saltwater Crocodile (Crocodylus porosus) are specifically mentioned to be deadly in ‘A Colour Atlas of Dangerous Marine Animals’ (Auerbach et.al, 1990), an illustrated book providing information and records of the species believed to be a danger to humans. The question of which of the two is more dangerous to humans is unclear due to the rarity of attacks however, by looking at evidence such as records of attacks,  (figure 3 and figure 4) and learning the behaviour of both species, it can be assumed that the less known Salt water crocodile tops the Great White Shark as most dangerous marine species out of the two.

References:

Auerbach, P.S, Campbell, D.R, Halstead, B.W (1990). A Colour Atlas of Dangerous Marine Animals. London: Wolfe Medical Publications.

Bruce, B.D, Stevens, J. D,  Malcolm H (2006) Movements and swimming behaviour of white sharks (Carcharodon carcharias) in Australian waters. Volume 150, Number 2.

Caldicott, D.G (2005). Crocodile Attack in Australia: An Analysis of Its Incidence and Review of the Pathology and Management of Crocodilian Attacks in General. Adelaide, Australia: Elsevier. 143–159.

ISAF Statistics on Attacking Species of Shark. Florida Museum of Natural History, University of Florida http://www.flmnh.ufl.edu/fish/sharks/statistics/species3.htm

Last, P.R & Stevens, J.D (2009). Sharks and Rays of Australia. 2nd ed. Melbourne: CSIRO. p176-177. http://www.publish.csiro.au/samples/Sharks%20and%20Rays%20of%20Australia.pdf

Peschak, T.P, Scholl, M.C (2006). South Africa’s Great White Shark. Cape Town: Struik. p19.

Ryan, C (1998) Saltwater Crocodiles as Tourist Attractions, Journal of Sustainable Tourism 6:4, 314-327 – http://www.tandfonline.com/doi/pdf/10.1080/09669589808667319

Shark Week on discovery channel – http://www.discovery.com/tv-shows/shark-week/#!/sun

Pictures:

Figure 1: Great White Shark http://animals.nationalgeographic.com/animals/photos/great-white-sharks/

Figure 1: Saltwater Crocodile http://animals.nationalgeographic.com/animals/reptiles/saltwater-crocodile/

Figure 2: Caldicott, D.G (2005). Crocodile Attack in Australia: An Analysis of Its Incidence and Review of the Pathology and Management of Crocodilian Attacks in General. Adelaide, Australia: Elsevier. 143–159.

Figure 3: ISAF Statistics on Attacking Species of Shark. Florida Museum of Natural History, University of Florida http://www.flmnh.ufl.edu/fish/sharks/statistics/species3.htm

Figure 4: http://theconversation.com/croc-attacks-a-new-website-with-bite-20671