How Great White Sharks Hide in Plain Water | Motherboard
A group led by UM assistant professor Dr. Neil Hammerschlag studied the techniques employed by the great whites in their hunting of Cape fur seals in False Bay, South Africa. The study helps confirm a notion, long held by surfers whose silhouettes look somewhat like a seal’s, that great whites always stalk their prey from below. While that in itself isn’t surprising, Hammerschlag’s research, published in Marine Biology Research, showed that the sharks camouflage themselves by taking advantage of water’s light-scattering properties. In low light conditions, when sunlight is hitting the water at a sharp angle, light does not penetrate deep into the water, and what light does is heavily distorted, essentially hiding the shark in otherwise clear water.
New Study Illustrates the Physics Behind Great White Shark Attacks on Seals | The Rosenstiel School of Marine and Atmospheric Science at the University of Miami
Scientists use basic principles of underwater optics, physics to understand predator-prey interactions
Sharks typically search, stalk and strike their prey from below. The vast majority of predatory strikes by sharks and Cape fur seals occur against small groups of young-of-the-year seals. Predatory activity by sharks is most intense within two hours of sunrise and quickly decreases as light penetration in the water column increases.
“Stealth and ambush are key elements in the white shark's predatory strategy,” said Hammerschlag.
Cape fur seals also have unique techniques to detect, avoid, outmaneuver and in some cases injure the white shark in order to avoid predation by sharks.
According to the authors, if a seal is not disabled during the shark’s initial shark, the small seal can use its highly maneuverable body to leap away from the shark’s jaws to evade a second strike.
Taylor & Francis Online :: Marine predator–prey contests: Ambush and speed versus vigilance and agility - Marine Biology Research - Volume 8, Issue 1
Differences in relative strengths and weaknesses between predators and prey under tactical contexts result in complex and dynamic contests between them. These contests are often brief and difficult to observe in marine systems. Here, we employ basic principles of underwater optics and physics to provide a conceptual understanding of mechanisms underlying predator–prey interactions between white sharks (Carcharodon carcharias) and Cape fur seals (Arctocephalus pusillus pusillus) that have been previously described at Seal Island in False Bay, South Africa.
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