A lure at both ends: Puff adders leave nothing to chance

Date: February 1, 2017

Source: University of the Witwatersrand

The Puff Adder (Bitis arietans) is one of Africa's deadliest snake species, not only due to its deadly venom, but also because of its stealthy behaviour in the way that it hunts by ambushing prey.

It has now emerged, however, that it has another deadly weapon in its arsenal, as it not only lies in wait for prey, but that it actively lures prey into striking range.

By capturing and analysing thousands of hours of video footage of puff adders hunting in the wild, Wits University researchers, Xavier Glaudas and Graham Alexander, have shown that puff adders use what is termed "lingual luring" to attract amphibian prey closer, and increase the odds of catching it.

"A puff adder's strike is typically no longer than one or two head lengths (5-10cm) in distance, so it needs a strategy to attract potential prey to come within that striking range in order to catch it," says Glaudas, a herpetologist and Post Doctorate Fellow at the Alexander Herpetology Laboratory at Wits University. "We have found that puff adders use their tongues that resemble an invertebrate that frogs feed on to increase prey capture rate."

Funded by the National Geographic Committee for Research and Exploration, Glaudas and Alexander tracked 86 puff adders over three years at the Dinokeng Game Reserve, about 100km north of Johannesburg in South Africa. Glaudas captured wild snakes and tracked them by surgically implanting radio transmitters into the snakes and releasing them at their place of capture.

"We really wanted to have a closer look into the secretive lives of these fascinating animals, and specifically study their foraging ecology," says Glaudas.

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Study of mountain lion energetics shows the power of the pounce

Date:

October 2, 2014

Source:

University of California - Santa Cruz

Summary:

High-tech collars enabled scientists to record the energetics of mountain lion hunting behavior, showing why cats use "stalk and pounce" and how they overpower large prey.

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Eyes On the Prey: Researchers Analyse the Hunting Behaviour of Fish Larvae in Virtual Reality

May 22, 2013 — Moving objects attract greater attention -- a fact exploited by video screens in public spaces and animated advertising banners on the Internet. For most animal species, moving objects also play a major role in the processing of sensory impressions in the brain, as they often signal the presence of a welcome prey or an imminent threat. This is also true of the zebrafish larva, which has to react to the movements of its prey. Scientists at the Max Planck Institute for Medical Research in Heidelberg have investigated how the brain uses the information from the visual system for the execution of quicker movements. The animals' visual system records the movements of the prey so that the brain can redirect the animals' movements through targeted swim bouts in a matter of milliseconds. Two hitherto unknown types of neurons in the mid-brain are involved in the processing of movement stimuli.

In principle, the visual system of zebrafish larvae resembles that of other vertebrates. Moreover, its genome has been decoded, it is a small organism, and it has transparent skin, which is easily penetrated by light in the fluorescent microscope. Therefore, these animals are very suitable for studying visual motion perception. They also display very clear prey capture behaviour. With the help of their finely-tuned visual system, they pursue and catch small ciliates. To do this, they execute a series of swimming manoeuvres in a matter of one or two seconds, during which they repeatedly verify the direction and distance of the prey so that they can adapt their subsequent movement steps. The larva's brain must, therefore, filter and evaluate visual information extremely rapidly so that it can select appropriate motor patterns.

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