Tiny Fish Make 'Eyes' at Their Killer

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Small prey fish can grow a bigger 'eye' on their rear fins as a way of distracting predators and dramatically boosting their chances of survival, new scientific research has found.
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39 Researchers from Australia's ARC Centre of Excellence for Coral Reef Studies (CoECRS) have made a world-first discovery that, when constantly threatened with being eaten, small damsel fish not only grow a larger false 'eye spot' near their tail - but also reduce the size of their real eyes.
The result is a fish that looks like it is heading in the opposite direction - potentially confusing predatory fish with plans to gobble them up, says Oona Lönnstedt, a graduate student at CoECRS and James Cook University.

For decades scientists have debated whether false eyespots, or dark circular marks on less vulnerable regions of the bodies of prey animals, played an important role in protecting them from predators - or were simply a fortuitous evolutionary accident.

The CoECRS team has found the first clear evidence that fish can change the size of both the misleading spot and their real eye to maximise their chances of survival when under threat.
"It's an amazing feat of cunning for a tiny fish," Ms Lonnstedt says. "Young damsel fish are pale yellow in colour and have this distinctive black circular 'eye' marking towards their tail, which fades as they mature. We figured it must serve an important purpose when they are young."
"We found that when young damsel fish were placed in a specially built tank where they could see and smell predatory fish without being attacked, they automatically began to grow a bigger eye spot, and their real eye became relatively smaller, compared with damsels exposed only to herbivorous fish, or isolated ones.

Dog Hair Can Be Used to Diagnose Hormonal Problems in Dogs

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        A surprisingly large number of dogs suffer from hyperadrenocorticism. The symptoms are caused by excessive amounts of hormones -- glucocorticoids -- in the body. Unfortunately, though, diagnosis of the disease is complicated by the fact that glucocorticoid levels naturally fluctuate and most methods for measuring the concentration of the hormones in the blood provide only a snapshot of the current situation.

 Recent research at the University of Veterinary Medicine, Vienna has shown that glucocorticoids accumulate in the animals' hair and that analysis of a dog's hair can provide quick and reliable preliminary diagnosis.
Just over a century ago, Harvey Cushing published an account of a young woman who showed unusual symptoms because her glands were making excessive amounts of something. 

Subsequent research has shown that the thing in question is a set of hormones known as glucocorticoids that are produced by the adrenal glands, so "Cushing's disease" is now more commonly known as hyperadrenocorticism, at least by those who can pronounce it. The condition is particularly common in dogs, particularly as the animals grow older. Most cases result from a tumour in the pituitary gland but some relate to tumours in one of the adrenal glands themselves.(http://animalzoon.blogspot.in/)

Life in Antarctica Relies on Shrinking Supply of Krill

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On the Antarctic island of South Georgia, in February, toward the middle of what passes for summer at the bottom of the world, I hurried through the ruined whaling station of Grytviken.

I had an appointment at the British Antarctic Survey station on the opposite side of King Edward Cove. I was to interview a marine ecologist working on krill. I did not want to be late.

The keystone of the South Georgia ecosystem, the secret to the miraculous abundance of wildlife on this stark, cold, windswept island—the foundation, indeed, for almost all vertebrate life in the Antarctic—is krill.

South Georgia and the South Sandwich Islands are administered from the Falkland Islands as a British Overseas Territory, in which the little outpost of Grytviken is the only inhabited spot. The inhabitation is very marginal. In southern winter there are just eight staff members of the British Antarctic Survey, including a doctor, a government officer, and a postal clerk. A handful of visiting scientists augment this skeleton crew in southern summer.

Grytviken is gritty and grim. The name means "Pot Bay," a reference to the cauldrons in which the Norwegian whalers here rendered oil from blubber. It is apt. The rusting vats, boilers, ramps, chimneys, and ramshackle buildings of the long-abandoned whaling station; the wrecks of the catcher boats stranded on the waterfront; and the rows of giant whale-oil tanks upslope are all the apparatus of a genocide, in the literal, Latin sense of the word. The genus was Balaenoptera, the baleen whale.

Shark Familes Not So Nuclear

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Discovery's Shark Week: Aug. 4-10.
Multiple paternity appears to be very common among sharks and has been documented in at least six species so far: leopard sharks, small-spotted catsharks, bonnethead sharks, lemon sharks, nurse sharks and sandbar sharks.

The most widely accepted explanation for multiple paternity is what's known as "convenience polyandry."

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"Basically, the female doesn't have much say about who she mates with," lead author Andrew Nosal of Scripps Institution of Oceanography's Marine Biology Research Division told Discovery News. "If a male encounters her and wants to mate, he will."

"At this point, the female has two options," Nosal continued. "She can attempt to fight and escape, but may incur greater injury in the process. Or she can acquiesce to minimize physical damage to her body...As a matter of convenience, to minimize the chance of injury, the female may just go along with it, even though there appears to be no biological need to mate with more than one male per reproductive cycle."

Nosal and colleagues Eric Lewallen and Ronald Burton focused their study on leopard sharks living off the coast of La Jolla, Calif. The study has been accepted for publication in the Journal of Experimental Marine Biology and Ecology.

To determine the number of shark dads per litter, the researchers took DNA samples from 449 leopard shark pups from 22 litters. The average litter size for this particular shark species is about 20 pups.