Whales coordinate deep dives to evade predators

FEBRUARY 6, 2020

by Nature Publishing Group

Groups of beaked whales reduce predation risk through extreme diving synchronization, according to a study in Scientific Reports. This behaviour has not been observed in other deep diving whales and the underlying reasons have remained unclear.

Natacha Aguilar de Soto, Mark Johnson and Peter Madsen and colleagues analysed data on 26 beaked whales carrying sensors that tracked the depths they swam to, the steepness of their dives, and the sounds they made.

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Turtle power: How hatching together avoids capture

July 5, 2016

New research has found that green turtles hatching en masse from their nests 'swamp' predators, allowing more individuals to reach the safety of the sea.

The study, by the Universidade Federal de Alagoas in Brazil and the University of Bristol in the UK, was carried out on a pristine and remote island near Brazil where there are 3,600 green turtle nests (Chelonia mydas) per year and very little human disturbance.

Researchers observed 33 of these nests every half an hour throughout the night to discover how simultaneously emerging from individual nests helps baby turtles to survival.

The main predator of green turtle hatchlings on the island is the yellow crab (Johngarthia lagostoma), which is not much larger than the hatchlings themselves. This means they have a long 'handling time' while they grapple with their bulky meal, so they were easily observable and remained close to the point of capture.

Findings, published in Proceedings of the Royal Society B today [6 July], show that mass departures of green turtle hatchlings saturates the foraging ability of the yellow crab, particularly as it spends a long time handling each prey item. Individuals emerging from their nests in bigger groups are therefore significantly more likely to survive.

Over 3,000 turtles hatched during the study. Typically 50 turtle hatchlings emerged at a time from a nest. Bigger groups led to decreased predation during the crawl to the sea, indicating that risk was 'diluted' between nest-mates.

Dr Christos Ioannou, a NERC-funded fellow from the School of Biological Sciences at the University of Bristol, said: "The biology of the turtles and crabs helps us rule out other possible ways for bigger groups to avoid predators; for example, the hatchlings don't team up to protect themselves.

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Nyah! Nyah! How Goldfish Eluded Huge Predator for Years

by Tia Ghose, Senior Writer | July 01, 2015 06:29pm ET

Talk about survival instincts.

A goldfish that was meant to be fish food found a hideout and lived in a tank with its predator for seven years, according to Japanese news reports.

The goldfish was tossed into the tank of an arapaima, a massive, predatory fish native to South America. But instead of going quietly to its fate, the plucky goldfish swam into a filtration unit in the tank at Japan's Shima Marineland aquarium. Workers discovered the lurker after a routine cleaning.

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Christmas colors disguise gliding lizards in the rainforest

Date:

December 24, 2014

Source:

University of Melbourne

Summary:

By mimicking the red and green colors of falling leaves, Bornean lizards avoid falling prey to birds whilst gliding, new research has found.

The work suggests that populations of the gliding lizard, Draco cornutus, have evolved extendable gliding membranes, like wings, which closely match the colours of falling leaves to disguise themselves as they glide between trees in the rainforest.

Found throughout South-East Asia, Draco is the only living genus of lizard with extendable gliding membranes -- call patagia -- which allow them to glide between trees in their territories.

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Watch: How turtles outsmart sharks

By Leon Siciliano, and Caters

3:56PM GMT 05 Dec 2014

Footage has emerged showing how a turtle moved its body to evade the jaw of a hungry tiger shark.

The video shows how the clever reptile turns on its side to make itself too big for the prowling predator's mouth.

To help confuse the shark even more, the turtle swims in circles that are too tight for the larger shark to catch it.

The fascinating footage was shot off the Cocos Islands, off Costa Rica, by scientist Randall Arouz.

Randall, from Florida, US, said: "The turtles have to have certain strategies to avoid being eaten.

Read on and watch video ...

Fast Camouflage: How the Goby Changes Color in One Minute

By Laura Geggel, Staff Writer | October 15, 2014 02:00pm ET

The unassuming rock goby, a small fish that can be found in rock pools around the United Kingdom, southern Europe and North Africa, is a master of camouflage, a new study finds.

Within a minute, the rock goby can change its color and brightness to disguise itself from hungry predators, such as birds and fish.

"These small fish that live in rock pools need excellent camouflage to avoid predators, and because they're often seen against many backgrounds, rapid color change enables them to be hidden in many places quickly," said lead researcher Martin Stevens, a senior research fellow in the Centre for Ecology and Conservation at the University of Exeter, in the United Kingdom.

Read on ...

Researchers find selective eaters less likely to be eaten

New research has found that dietary specialization among herbivores, specifically caterpillars, indicates whether or not they are better able to hide themselves from predators such as birds. The research suggests those herbivores who dine on a wide variety of plants face an increased chance of being eaten by birds whereas those with a limited diet are less likely to be eaten.

The research titled, Herbivore diet breadth mediates the cascading effects of carnivores in food webs, and published recently in the Proceedings of the National Academy of Sciences, shows the far-reaching effects of herbivore dietary specialization on the ecological and evolutionary dynamics of carnivore–herbivore–plant interactions.

The research was led by Mike Singer, associate professor of biology and associate professor of environmental studies, at Wesleyan University. The collaboration included UNM Department of Biology Associate Professor Kenneth Whitney and four others.

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Frogs with vivid colour markings to ward off predators can also appear invisible - via Herp Digest

June 23rd, 2014 (Phys.org) —Frogs that rely on their vivid colour markings to ward off predators can also appear invisible, Deakin University scientists have discovered.

Researchers from Deakin University's Centre for Integrated Ecology found the anomaly among a species of frog in which some individuals use their rainbow hues to warn they are poisonous or toxic while others rely on their colourings to make them difficult to detect.

Centre for Integrated Ecology evolutionary biologist Professor John Endler and his Ph.D. student and co-author studied poison dart frogs in the wild and identified the reason behind the paradoxical observation that the amphibian's colourful markings varied between each animal.

Studying the vibrant blue and yellow poison dart frogs (Dendrobates tinctorius) in their natural habitat in French Guiana, Deakin researcher Bibiana Rojas found that one group of frogs exhibited bold or elongated patterns, the other demonstrated mottled and more variable markings.

The paradox was that the more variable the frog's markings, the less likely were predators to learn to recognise the danger. But if different colour patterns accompanied different behaviour, then pattern variation can be an advantage instead of a disadvantage.

"We found that some frogs move frequently in the same direction while others moved randomly, and that this movement behaviour variation corresponded to the colour patterns," Professor Endler said.

"The frogs with elongated patterns moved continuously in the same direction to create an illusion of static pattern, or a pattern travelling at a slower speed, to thwart predators attempting to track their trajectory.

"But frogs which moved randomly and changed directions frequently, rely on interrupted colour patterns that appear visually disruptive and hard to see at a distance, giving them an advantage in predator detection rather than tracking.

"These findings are quite exciting as we believe they might have application in the human world for defence camouflage," Professor Endler said.

"Alternatively, taxis, police cars, and ambulances could be painted with horizontal stripes to make them more easily seen when they are going past."

Professor Endler has been studying aposematic animals for many years - species that use colour in the wild to either attract a mate or ward off predation.

In Australia, Blue-ringed octopus and redback spiders, and the introduced Monarch Butterfly are among a variety of animal species instantly recognised for their chromatic colours that warn of their danger to would-be predators.

Black, red, yellow and white are among the bold colour schemes employed in nature to warn of danger.

The researcher's report, "Paradox lost: variable colour-pattern geometry is associated with differences in movement of aposematic frogs", has been published in the latest copy of the prestigious Royal Society Journal Biology Letters.

More information: Bibiana Rojas, Jennifer Devillechabrolle, and John A. Endler. "Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs." Biol. Lett.. 2014 10 6 20140193; DOI: 10.1098/rsbl.2014.0193 (published 18 June 2014) 1744-957X

Provided by Deakin University

Do butterfly wing patterns really mimic predator eyes?

23 July 2014 Last updated at 05:32

By Ella Davies

Science writer

A bumper crop of spikey black caterpillars have appeared on the nation's nettles this summer.

Clad in velvet coats peppered with white dots, the creatures have been sunning themselves and munching through the weeds in remarkable numbers prompting a flurry of enquiries and reports to the charity Butterfly Conservation.

They might not be so familiar in this form but the insects will grow up to be arguably Britain's most colourful and recognisable butterfly - the peacock.

As they prepare for their annual Big Butterfly Count, experts at the charity are predicting a bonanza of the butterflies.

Last year, the species surged to third position in the survey which asks the public to record how many butterflies they see in 15 minutes of sunny weather.

Following on from this success, peacocks emerged in good numbers after their winter hibernation according to Butterfly Conservation's Surveys Manager Richard Fox. The warm, dry weather since the spring has provided ideal conditions for breeding, egg-laying and the development of caterpillars.

read on

Scientists unravel the genetic secrets of nature's master of mimicry

Scientists investigating how one of the greatest shape shifters in the natural world is able to trick predators to avoid being eaten have identified the gene behind the fascinating feat.

The African Swallowtail butterfly, also known as the 'Mocker Swallowtail' or the 'Flying Handkerchief,' can appear to change both colour and shape.

Males of the species fly boldly around the tree tops, their rapid flight making them look like shaking handkerchiefs, however females lurk in the bushes and pretend to be examples of Monarch butterflies that are nasty to eat.

The females mimic different Monarchs in different parts of Africa and how they do this has long been a mystery. In an international collaboration involving scientists from the Natural History Museum, Imperial College London, the University of Cambridge and researchers in Nairobi, Paris and Jena in Germany, The University of Exeter's Professor Richard ffrench-Constant (correct spelling) has helped solve the genetic switch that allows female swallowtails to look like different Monarch butterflies and thus avoid being eaten.

Read more at: 

Spiders Pose as Bird Poop to Evade Predators

By Tanya Lewis, Staff Writer | May 29, 2014 11:57am ET

Many animals camouflage themselves to avoid being eaten by predators, but few are as strange as a spider that disguises itself as bird poop.

The orb-web spider's silver body and the white, silken, disclike decoration on its web give it an uncanny resemblance to bird droppings. The spiders may use this disguise to avoid being captured by predatory wasps, researchers say.

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How Legless, Leaping Fish Living On Land Avoids Predators

Dec. 2, 2013 — One of the world's strangest animals -- a legless, leaping fish that lives on land -- uses camouflage to avoid attacks by predators such as birds, lizards and crabs, new research shows.

UNSW researchers, Dr Terry Ord and Courtney Morgans, of the Evolution and Ecology Research Centre, studied the unique fish -- Pacific leaping blennies -- in their natural habitat on the tropical island of Guam.

Their study will be published in the journal Animal Behaviour.

"This terrestrial fish spends all of its adult life living on the rocks in the splash zone, hopping around defending its territory, feeding and courting mates. They offer a unique opportunity to discover in a living animal how the transition from water to the land has taken place," says Dr Ord, of the UNSW School of Biological, Earth and Environmental Sciences.

Read on

Stressed-Out Tadpoles Grow Larger Tails to Escape Predators

Mar. 5, 2013 — When people or animals are thrust into threatening situations such as combat or attack by a predator, stress hormones are released to help prepare the organism to defend itself or to rapidly escape from danger -- the so-called fight-or-flight response.

Now University of Michigan researchers have demonstrated for the first time that stress hormones are also responsible for altering the body shape of developing animals, in this case the humble tadpole, so they are better equipped to survive predator attacks.

Through a series of experiments conducted at field sites and in the laboratory, U-M researchers demonstrated that prolonged exposure to a stress hormone enabled tadpoles to increase the size of their tails, which improved their ability to avoid lethal predator attacks.

"This is the first clear demonstration that a stress hormone produced by the animal can actually cause a morphological change, a change in body shape, that improves their survival in the presence of lethal predators. It's a survival response," said Robert Denver, a professor of molecular, cellular and developmental biology and of ecology and evolutionary biology.

Continued:  http://www.sciencedaily.com/releases/2013/03/130305200204.htm

Shark embryos 'freeze' to evade predators

Bamboo shark embryos developing in egg cases stay still to evade predators, scientists say.

Australian researchers found that the embryos could identify electric fields simulating a nearby predator, despite being confined to a tiny egg case.

On sensing danger, they "froze" and temporarily stopped breathing to avoid being detected.

Sharks use jelly-filled pores on their heads called electroreceptors to recognise other animals.

These highly sensitive receptors enable sharks to locate prey, predators or potential mates from minute bioelectric fields.
The study, by scientists from the University of Western Australia, Crawley, near Perth, suggests brownbanded bamboo shark (Chiloscyllium punctatum) embryos are able to employ similar methods to detect predators.

"Embryonic sharks are able to recognise dangerous stimuli and react with an innate avoidance response," explained Ryan Kempster, a shark biologist and member of the research team.

The team's findings are published in the journal PLoS ONE.

Brownbanded bamboo sharks grow up to 1.2m (3.9ft) in length and are found in the Indo-West Pacific region as well as coastal areas of northern Australia and southern New Guinea.

Continued: http://www.bbc.co.uk/nature/20945543

Fawns use 'escape plan' to evade predators

Fawns often bypass the nearest "escape cover" to seek out better habitats for shaking off predators, new research has found.

Baby deer are more likely to survive if they use this selective technique rather than simply fleeing to the closest refuge.

The study in the journal Animal Behaviour, followed white-tailed deer fawns in the Great Plains of the US.

The fawns' behaviour was a surprise to the research team, they said.

"We expected them to look for cover as soon as possible and try to take that cover… (but) they actually went to a better cover rather than the first available," says Jonathan Jenks, distinguished professor of wildlife and fisheries sciences at South Dakota State University.

Fawns selecting grassland and wetland habitats to conceal themselves in were found to be more likely to evade predators such as coyotes, even if it meant them running greater distances to reach these terrains, the study said.

But those choosing forest sand wheat fields were more likely to be captured.

Read on:  http://www.bbc.co.uk/nature/18040372