Monday, 24 April 2017

Tarantulas use their lateral eyes to calculate distance

Date: April 20, 2017
Source: FECYT - Spanish Foundation for Science and Technology
 
The tarantula species Lycosa tarantula ambushes its prey and lives in burrows around 20 cm deep topped by a structure, a kind of turret which the tarantula build from twigs, leaves and small stones, fastened with the spider's silk. From the turret, the tarantula surprises its prey and runs to pursue it, subsequently returning to the burrow from distances between 30 and 40 cm.

L. tarantula uses path integration to return to its burrow. With this mechanism, it does not follow the same path back to its burrow; instead, it moves as though it had followed the sides of a right-angle triangle, returning along the hypotenuse.

In 1999, a research team from the Autonomous University of Madrid discovered that these animals used polarised light from the sky to know their position with respect to their nest. In the new research, the scientists wanted to go beyond this, and have analysed the role of each pair of the tarantula's eyes (they have four pairs in total) in the process of distance measurement, or odometry.

"To calculate the distance it has travelled, the animal needs an odometer that registers the route, its location with respect to the finish point, which would be the burrow, and a 'compass' to track the direction of travel," according to Joaquin Ortega Escobar, lead author of a paper published in the Journal of Experimental Biology on the function of each eye in these processes.

The 'compass' would correspond to polarised light, which the median eyes use to measure the angle; direction is detected by the anterior lateral eyes. Through this research, the scientists have learned that it is principally the anterior lateral eyes (which until now had not been analysed), and to a lesser extent the posterior lateral eyes, that help tarantulas measures the distance to their nest.

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Recovering species must be celebrated or we risk reversing progress


Date: April 20, 2017

Source: University of Cambridge
 

A failure to celebrate conservation successes means we miss vital opportunities to convince the public of "real and practical solutions" they can engage with, says a leading conservationist.

Writing in the journal Oryx, Andrew Balmford, Professor of Conservation Science at the University of Cambridge, argues that any progress risks being reversed if we "let drift the many gains that the conservation movement is making."

Progress redefines what we consider normal, he says, as in the case of the smoking ban or rights for women. Such "positive shifting baselines" even extend to the green shoots of nature's recovery through conservation -- from birdlife in the UK's Avalon marshes to monkeys in Brazilian forests.

However, Balmford says conservation improvements can quickly get taken for granted. When combined with the seemingly endless torrent of bad news about nature, he believes the overall effect can render people hopeless.

"If we forget where we've come from, we risk allowing things to slip backwards," he writes, pointing to examples in the UK and US where early species recoveries have already led to official sanctioning of hunting and culling of partially restored populations.

In an effort to shift the balance towards celebrating and reinforcing success, Balmford and colleagues from the Cambridge Conservation Initiative are organising Cambridge University's contribution to a day of global action. #EarthOptimism will promote a much more positive outlook on the future of the natural world.



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Genetic evidence points to nocturnal early mammals

Date: April 20, 2017
Source: Stanford University


Our earliest mammalian ancestors likely skulked through the dark, using their powerful night-time vision to find food and avoid reptilian predators that hunted by day. This conclusion, published by Stanford researchers April 21 in Scientific Reports, used genetic data to support existing fossil evidence suggesting that our distant relatives may have adapted to life in the dark.

The team, led by Liz Hadly, professor of biology and senior author on the paper, examined genes involved in night vision in animals throughout the evolutionary tree, looking for places where those genes became enhanced.

"This method is like using the genome as a fossil record, and with it we've shown when genes involved in night vision appear," Hadly said. "It's a very powerful way of corroborating a story that has been, up to now, only hypothesized."



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Sea Urchins Launch Their Weird Mobile Jaws to Scare Predators

By Stephanie Pappas, Live Science Contributor | April 24, 2017 07:08am ET

A common and colorful sea urchin has some truly bizarre appendages that seem to move independently from its body, and now scientists know why: It shoots these tiny, venomous jaws into the water to deter predators.

These teensy, toothy jaws are called pedicellariae, and when scientists discovered them in the early 1800s, they thought the jaws were parasites because they seemed to move independently from the urchin. Now, researchers find that urchins use their pedicellariae not only to defend themselves when attacked, but also as a warning to fish and other sea creatures to "stay away!"

Tripneustes gratilla, otherwise known as the collector urchin, is a widespread species found in shallow waters in the Bahamas, the Indo-Pacific region and even the Red Sea.



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Sunday, 23 April 2017

Hunt Kicks Off for 'Teddy Bear' Marsupial and Other 'Lost' Species

By Stephanie Pappas, Live Science Contributor | April 21, 2017 12:05pm ET

A duck with a pink head, a tree-climbing crab, and a monkey with red thighs are among the targets of a new global hunt for "lost" species.

Global Wildlife Conservation (GWC), an organization based in Austin, Texas, with a focus on biodiversity and wildland preservation, has launched a new initiative to search for 25 species that have not been seen for years or decades — or, in the case of the Fernandina Galapagos tortoise, more than a century. The goal is to see if any of the species still survive and, if so, save them.

"While we're not sure how many of our target species we'll be able to find, for many of these forgotten species, this is likely their last chance to be saved from extinction," GWC spokesperson Robin Moore said in a statement.

The group is focusing on species that have not been seen since at least 2007. Collaborating with the International Union for Conservation of Nature (IUCN), GWC actually came up with a list of 1,200 "lost" species but chose the charismatic creatures with decent chances of being saved, if they can be found.

On the list is the Syr-darya shovelnose sturgeon (Pseudoscaphirhynchus fedtschenkoi), a fish once found only in the Syr Darya river of Kazakhstan, Tajikistan and Uzbekistan that has not been seen since the 1960s. Both the silvery Zug's monitor (Varanus zugorum) and the Wallace's giant bee (Megachile pluto), the latter of which is considered the world's largest bee, have been missing from Indonesia since the early 1980s. Another lost denizen of Indonesia is the Wondiwoi tree kangaroo (Dendrolagus mayri), a teddy-bear-faced marsupial missing since 1928.



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