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Science/Tech See other Science/Tech Articles Title: Turtle telepathy ADELAIDE: River Murray Turtle embryos can adjust their developmental rate so that all the eggs in a clutch can hatch around the same time, a new study has found. Young turtles face many challenges when they hatch and venture into the world. Synchronous hatching increases their survival chances, as predators are swamped by high numbers of prey. As a large group, hatchlings can also work together to dig their way out of the nest more easily. Scientists investigated incubation and group hatching in the River Murray Turtle, which is a species restricted to the Murray-Darling River system in southeastern Australia. Although the temperature of the nest affects the developmental rate of eggs, researchers discovered another factor that influences their growth rate ― embryo to embryo communication. "Turtle embryos are somehow communicating their developmental rates to each other so that they can emerge as a group," said Ricky-John Spencer, zoologist from the University of Western Sydney, and co-author of the study published in Proceedings of the Royal Society today. Importance of temperature for the embryo For many reptiles, temperature plays a key role in the development of eggs. Warm temperatures speed up embryonic development and shorten the incubation period. However, temperatures in different parts of a turtle nest can vary by several degrees. River Murray Turtles lay large numbers of eggs (up to 30 in one clutch). Eggs near the top of the nest are exposed to warmer temperatures and develop faster than those in the bottom layers. Surprisingly though, all the eggs still hatch at a similar time. In order for synchronous hatching to occur, biologists previously thought that the cooler eggs hatch prematurely, resulting in turtles with underdeveloped muscular and nervous systems. For example, in a freshwater turtle species in North America, eggs that were exposed to lower temperatures and hatched prematurely produced turtles with reduced motor skills in the first nine months of life. However, in this study, researchers found that River Murray Turtle eggs in the cooler patches of the nest can adjust their metabolic rates and increase their development, allowing them to catch up to their more advanced siblings. During the experiment, scientists exposed half an egg clutch to a different temperature for a week. Then they returned the eggs to one pile for the rest of the incubation period. Eggs are porous structures that take up oxygen and release carbon dioxide. So researchers were able to monitor metabolic rates by measuring gas exchange in and out of the eggs. They also measured embryo heart rates. Speeding up development "In the last third of incubation, eggs that were in the presence of more advanced eggs started to increase their metabolic rates and heart rates," said Spencer. In the nest there is some type of signalling between the unborn siblings that enables all eggs to develop fully and hatch together, regardless of the temperature differences. However, scientists are unsure exactly how this phenomenon works. They suspect that carbon dioxide levels or heart rates may be cues for increased metabolism, but further studies are needed to investigate these factors. Unlike the North American species, the River Murray Turtle displayed no negative effects from speeding up their development in the last phase of incubation. After hatching, their nervous and muscular systems functioned normally. This is important for the young critters as a decreased ability to run, swim and escape may make them easy targets for predators. "This paper shows that the mechanism for synchronising emergence within a clutch is not actually determined by temperature, which is what we normally use for determining incubation duration," commented marine biologist Michael Guinea from Charles Darwin University in the Northern Territory, who specialises in sea turtle research. Guinea also said that it would be interesting to compare other turtle species with these freshwater ones. This may shed some light on whether these embryonic responses are common among other species or are unique to the River Murray Turtle. Follow COSMOSmagazine on TwitterJoin COSMOSmagazine on Facebook Post Comment Private Reply Ignore Thread Top • Page Up • Full Thread • Page Down • Bottom/Latest Begin Trace Mode for Comment # 1.
#1. To: abraxas (#0)
Turdle Ping.
#2. To: Original_Intent, abraxas (#1)
Turtles are wonderful, but greyhounds are ugly, smelly, retarded dogs.
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