Washington: A new study has shown that some shark species are able to navigate to specific locations up to 50km away.
Re-analysing tracking data from tagged sharks, ecologists found that while some species such as blacktip reef sharks swim in a pattern known as a "random walk", others such as tiger sharks can at times hunt for prey or mates by using "directed walks", accurately navigating long distances across open ocean, often at night.
To maximise lifetime fitness, animals should optimise search patterns for finding food, mates and safety. In new and unfamiliar locations, animals use different types of random walk. However, many animals occupy large home ranges where they will develop mental maps of the locations of resources and use directed walks (movements to known goals) to move between these locations. Few studies have quantified directed walks in animals.
The data show that tiger sharks not only know where they are going but can find their way to a feature at least 6-8 km ahead of them, although how they do this remains a mystery.
"Many people could walk to a known destination 6-8km away, but imagine doing it in deep water and at night. As anyone who dives knows, finding your way around underwater without a compass is very difficult, but this is what we found tiger sharks could do," said lead author Yannis Papastamatiou of the Florida Museum of Natural History.
Sharks have impressive sensory abilities. They have good hearing, vision and smell, can detect certain chemicals at very low concentrations and low frequency sounds at least several hundred hundred metres away. An increasing amount of evidence also suggests they may navigate by using the Earth``s magnetic field.
The new study has been published in the British Ecological Society``s Journal of Animal Ecology.