Turtles 'communicate with each other before hatching'

Scientists believe baby turtles can communicate with each other before they hatch and can arrange to emerge from their eggs at the same time.

A study of Australia's Murray short-necked turtle found the embryos synchronised their hatching to prevent smaller turtles emerging alone and being attacked by predators such as goannas and foxes.

It is believed the unhatched turtles, which lie enclosed in a tight nest, may be able to sense each other's heart vibrations or may detect gases emitted from the breath of other turtles. In this way, more developed turtles can send signals on their growth status to less developed ones to encourage them to increase their growth rates.

"I am pretty sure they're not sitting there chatting to each other but no one really knows," said Dr Ricky Spencer, a co-author of the new study.

The researchers, from the University of Western Study, said that embryos positioned at the bottom of the nest – where temperatures are lower – have a "catch-up mechanism" which enables them to overcome their longer incubation periods. However, the precise nature of the mechanism remains unknown.

"They might be cueing in on heart rates," Dr Spencer told ABC Radio. "They are all touching each other within the nests so there might be vibrations there. A nest environment is pretty much an enclosed cavity where gas exchange might be a cue as well ... They breathe, so if you get increases in carbon dioxide within a nest they might be cueing on in that."

The researchers studied the turtles by dividing a clutch of eggs into two and incubating them at different temperature levels. They then united the eggs after a week and analysed the embryonic heart rates and metabolic rates. During the last third of the incubation period, the cooler embryos had sped up their heart rate and metabolism and hatched within a couple of days of the warmer ones.

"They increased their developmental rate essentially independent of temperature [and] that allowed them to hatch earlier," Dr Spencer said.

http://www.telegraph.co.uk/news/newstopics/howaboutthat/8925107/Turtles-communicate-with-each-other-before-hatching.html