Showing posts with label hunting technique. Show all posts
Showing posts with label hunting technique. Show all posts

Thursday, June 10, 2010

Pelagic Predators & Math: study finds hunting patterns not just random

Do pelagic predators hunt in random patterns or with some more organized approach that actually has some mathematical significance? Underwater Times picked up on an article in ScienceNews, about a study showing that fish like tuna, billfish, and some sharks exhibit a mathematical logic in their movements, called a Lévy walk or flight.

In tracking various ocean predators, the researchers noted foraging patterns that were not random - moving here and there without any particular method to their movements - but more deliberate, punctuated with long movements and demonstrating evidence of mathematical fractals.

A fractal is a mathematical pattern that is used to describe the shapes of many things, from snowflakes to the shapes of leaves. No, snowflakes and leaves don't have intelligence, at least not intelligence that necessarily demonstrates free will. But in analyzing the foraging patterns of their test subjects, the researchers detected a level of mathematical thinking or intelligence that was not purely random-based, which was the prevailing theory in the past.

"Many of the animals displayed Lévy behavior at least some of the time, researcher David Sims and his colleagues report — 'the strongest evidence yet that these Lévy patterns are exhibited by wild animals,' he says. Lévy behavior showed up more often in waters where plankton, fish and other food was scarce. In regions with plentiful food, random motion dominated. This observation, says theoretical physicist Gandhimohan Viswanathan, fits with earlier suggestions that 'animals may use a Lévy flight motion to improve their chances of finding prey.'”

This kind of research can provide more insight into migration and other feeding patterns based on availability of food. Perhaps in the future we can better understand or anticipate the actions or movements of some species or their ability to adapt when environmental conditions change.

Read ScienceNews article.

Tuesday, May 18, 2010

A Thresher's Tale (Tail): video footage solves a shark's mystery

One of the ocean's most unusual sharks, the thresher shark, has carried with it a great mystery: why the elongated upper caudal (or tail) fin? Suspicions were that it was used to strike and stun its prey. However, there wasn't any definitive documentation (ie: video or motion picture footage) to confirm it. Until now. . .

According to the BBC News, Dr. Chugey Sepulveda of the Pfleger Institute of Environmental Research in Oceanside, California, captured some brief images of a thresher shark swatting several smaller fish and stunning or outright injuring them, making them easy prey.

The water visibility is a bit murky and it all happens in a blink of an eye, but the video slows it down to half speed and you can clearly see the shark's unique hunting ability. The BBC doesn't allow for embedding a video, so click on the image below to link to the BBC and view the footage.

Followers of great white sharks at Isla Guadalupe are very familiar with the Pfleger Institute as they were one of the first organizations to do an exhaustive picture cataloging of the island's population of white sharks that migrate there every fall.

Kudos to the Dr. Sepulveda. These are very special sharks - all three species of thresher sharks are listed as "vulnerable to extinction" by the International Union for Conservation of Nature (IUCN).