A Description of the Great White Shark behaviour at Seal Island
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(Partial Predatory Ethogram of the Great White Sharks at Seal Island)
Great White Shark ‘Polaris Attack’ – the attacking shark performs a swift, vertical rush; often leaping partially or completely out of the water, with or without a seal in its mouth. If a seal is in the shark’s mouth, it typically shakes its head violently from side-to-side, possibly facilitating death or severe injury via neck trauma caused by the ‘Lateral Head Shake’. This is typically devastating, usually killing or incapacitating the seal in the initial strike. Those seals which are wounded but not killed in this strike typically bear slashing wounds on the posterior abdomen (probably inflicted by the attacking shark’s lower anterior teeth, which form the first point of contact between predator and prey), usually located on the rearmost quarter of the body.
Great White Shark ‘Surface Breach’ – after the initial strike, if the seal is still alive, the attacking shark performs a swift shallow, horizontal breach, typically re-entering water with its jaws over the seal, usually forcing the seal underwater. Seals struck in this way are typically wounded on the posterior quarter of the body. If the seal is in the shark’s mouth, it typically shakes its head violently from side-to-side, possibly facilitating death or severe injury via neck trauma caused by the ‘Lateral Head-Shake’, which is often fatal; and sometimes accompanied by ‘Side Roll’.
Great White Shark ‘Side Roll’ – after the initial strike, if the seal is still alive, the attacking shark performs a moderately fast lateral roll at or near the surface, possibly to keep the floating seal in sight or perhaps an artifact of continued pursuit. One of the shark’s pectoral fins often protrudes from the water.
Great White Shark ‘Lateral Snap’ – when a seal is ‘working a shark’ (performing zig-zag surface maneuvers in an attempt to stay away from a pursuing shark’s jaws), the attacking shark performs a sudden, swift lateral snap of its head, typically grasping the seal with its latero-posterior teeth. Seals grasped in this way are typically grasped mid-body, at roughly the level of the fore-flippers.
Great White Shark ‘Lateral Head-Shake’ – when a seal has been grasped during pursuit or killed, the attacking shark performs violent lateral shakes of the head. This action typically breaks the neck of a seal that has not yet succumbed or, if dead, maximises the cutting efficiency of the shark’s serrated dentition by sawing apart the ribcage, which is usually the only potion of a seal carcass that provides any significant resistance to being sundered by the shark’s teeth.
Great White Shark ‘Killing Bite’ – when a seal has been grasped during pursuit, the attacking shark performs a swift, powerful bite to the seal’s head or neck, efficiently killing the prey prior to feeding upon its carcass. This is often followed by ‘Surface Grasp’.
Great White Shark ‘Surface Grab’ – after the seal is dead or otherwise incapacitated, the attacking shark performs a slow, almost ‘casual’ grasp of the floating seal. The shark typically employs its anterior teeth for doing so, often raising its head partially out of the water. This is often followed by ‘Lateral Head-Shake’ or ‘Subsurface Carry’.
Great White Shark ‘Subsurface Carry’ – after the seal is dead or incapacitated and other sharks (competitors) are in the immediate vicinity (a kill often draws as many as four additional White Sharks), the attacking shark may slowly grasp and carry the seal’s body underwater some distance – typically 5 to 8 metres or so – possibly to assert its ownership of the prey item or to otherwise discourage competitors from stealing it.
Great White Shark ‘Surface Feed’ – after the seal is dead, the attacking shark consumes the prey. Due to its high blubber content, the seal carcass floats at the surface and it is there that the shark calmly but efficiently feeds upon it. Consumption is typically performed in two or three massive bites – often employing ‘Lateral Head-Shake’ to saw apart the carcass’ rib cage – and lasts a duration of less than a minute. The seal’s entrails are rarely consumed by a feeding White Shark (although the Kelp Gulls and other seabirds compete vigorously and noisily for some) and the head is sometimes also abandoned (low quality food item?) to sink out of sight, probably to be picked clean by crabs and other benthic scavengers.
Join Rob Lawrence and the African Shark Eco-Charters team on one of our popular “Airjaws” trips to experience the predatory strategies of the Great White Shark first-hand.
Data collected and observations by R. Aiden Martin of the ReefQuest Centre for Shark Reasearch, as well as Rob Lawrence.
Picture taken by Rob Lawrence
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