Tadpoles hatch in seconds to escape predator

Date: June 16, 2016

Source: Smithsonian Tropical Research Institute

Although red-eyed tree frog embryos appear helpless within their jelly-coated eggs, they can hatch up to two days ahead of schedule, reacting within seconds to attacks by egg thieves. At the Smithsonian Tropical Research Institute (STRI) in Panama, scientists used high-speed video to uncover their rapid-hatching secret.

"Most people think of embryos as fairly passive," said Karen Warkentin, STRI research associate and professor at Boston University. "But evidence keeps accumulating that embryos of many species are actively engaged with their world, not only receiving information but also using it to do things that help them survive."

This is particularly true of the embryos of red-eyed tree frogs (Agalychnis callidryas). Native to Neotropical rainforests, adult frogs live in trees and lay clusters of 40 or so eggs on leaves, branches or other structures that overhang ponds or streams. Left undisturbed, tadpoles hatch after a week's development inside the gooey egg mass and drop into the water below. But the eggs are often attacked by hungry snakes or wasps and are also vulnerable to sudden environmental events like floods or heavy downpours. Developing embryos are able to assess the level of threat and have evolved a quick-release mechanism to escape the egg prematurely.

Continued … 

Fish Migrate to Escape Predators

Mar. 1, 2013 — By individually tagging fish in a lake and following their movements, a research team has shown that migration is a very effective defence against being eaten.

Each year billions of animals make annual migrations to escape adverse environmental conditions. Migration is a spectacular and important biological phenomenon, but studying what drives animals to make these arduous journeys is extremely difficult. Food and climate are classic explanations for animal migration, but the idea that animals migrate to escape predators is less well studied. Senior scientist Christian Skov, DTU Aqua and colleagues from Lund University, Sweden and Eawag, Switzerland now present direct evidence that migrants benefit by evading predators.

The biologists tagged more than 2000 individual fish (roach, Rutilus rutilus) in two Danish lakes over 4 years and monitored migratory behaviour using passive telemetry. Next, they calculated the predation vulnerability of fish with differing migration strategies, by recovering data from passive integrated transponder tags of fish eaten by cormorants (Phalacrocorax carbo spp.) at communal roosts close to the lakes. The results are published in Biology Letters.

Continued:  http://www.sciencedaily.com/releases/2013/03/130301034605.htm

'Scar free healing' in mice may give clues to human skin repair, says study

Mice with brittle skin, which tears off in order to escape predators, may offer clues to healing wounds without scarring, according to US researchers.

Some African spiny mice lost up to 60% of the skin from their backs, says the study published in the journal Nature.

Unlike wounds in other mammals, the skin then rapidly healed and regrew hairs rather than forming a scar.

Scientists want to figure out how the healing takes place and if it could apply to people.

Salamanders, some of which can regrow entire limbs, are famed for their regenerative abilities. It has made them the focus of many researchers hoping to figure out how to produce the same effect in people.

Mammals, however, have very limited ability to regrow lost organs. Normally a scar forms to seal the wound.
Continued: http://www.bbc.co.uk/news/health-19727622