Variation in male, female turtle shells provides advantage when facing predators
Released: 11/15/2011 2:00 PM EST
Source: Allen Press Publishing Services
News Release
FOR IMMEDIATE RELEASE
Newswise - Herpetologica - One way to tell a male turtle from a female turtle is a difference in the shape of their shells. While this pattern of sexual dimorphism is common among turtle species, it could have other effects on turtle biology. The differing shell designs may exhibit different strengths in standing up to the attack of a predator, and therefore the survival rate of one sex over the other.
The current issue of the journal Herpetologica reports on the mechanical implications of shell shape differences between two species of male and female turtles. The Painted Turtle (Chrysemys picta) is an aquatic species, and the Wood Turtle (Glyptemys insculpta) is a terrestrial species.
Females turtles tend to have larger, domed shells, which may indicate the ability to hold large clutches of eggs. Males, on the other hand, typically have flatter shells and larger openings for their limbs, allowing them greater movement. This improves their success in courtship and mating.
To test the strength of these varying shells, researchers created digital models of the shells for finite element analysis. This computer model uses simple geometric shapes to create a complex structure-the turtle shell in this case. It then calculates the response of those elemental shapes to create the response of the shell as a whole. Twelve load conditions, representing the bite of a predator at different locations, were applied.
The females of both species fared better than the males, although male and female Wood Turtles were more evenly matched. Female shells showed less stress than male shells. The concave shape of the plastron, or underside, of the male Wood Turtle's shell in particular exhibited significantly increased stress, indicating it would be more easily punctured by a predator.
These differences between sexes may stem from selection based on other factors besides predation. Currently, there are no data showing that females are more likely to encounter predators, for instance, and that therefore their shells have become better able to withstand such attacks. However, these variations can have an effect on turtles' lives and offer important implications for turtle conservation efforts.
Full text of the article "Dimorphism in Shell Shape and Strength in Two Species of Emydid Turtle," Herpetologica, Volume 67, Issue 4, November 2011, is available at: http://www.hljournals.org/
Showing posts with label wood turtles. Show all posts
Showing posts with label wood turtles. Show all posts
Saturday, November 19, 2011
Saturday, November 6, 2010
New Culvert Bids An Cost Savings (for wood turtles)
November 01, 2010, By LORI STABILE
PALMER - The discovery of wood turtles, a state-protected species, near a damaged culvert on Quaboag Street in Three Rivers forced a redesign of the culvert's replacement, but it turned out to be less expensive for the town in the end.
Acting Town Manager Patricia A. Kennedy said out of 10 bids submitted on Wednesday, Hammond Construction, of North Oxford, was the low bidder with $38,053.
The first time the project was advertised, the low bid was $49,000, she said.
The Town Council recently appropriated $62,000 from the stabilization fund to repair the culvert, which is near the Quaboag River. The culvert collapsed after a summer rainstorm, resulting in erosion and encroachment on a neighboring shed.While the area was stabilized with hay bales, that was only a temporary fix.
Said Acting Public Works Department Superintendent Richard P. Kaczmarczyk, "Hopefully we'll get it going in the next few weeks."
The first bid was rejected after the issues with the wood turtle were discovered by the state's natural heritage program during the review process, Kennedy said.
She said this wasn't the first time the wood turtle altered a project in the village of Three Rivers, noting the recent Springfield Street reconstruction.
A "special walkway" under Springfield Street, by the pond near the blueberry farm, was made for them so they could cross the road without getting crushed by cars.
From: HerpDigest Volume # 10 Issue # 47 11/5/10 (A Not-for-Profit Publication)
PALMER - The discovery of wood turtles, a state-protected species, near a damaged culvert on Quaboag Street in Three Rivers forced a redesign of the culvert's replacement, but it turned out to be less expensive for the town in the end.
Acting Town Manager Patricia A. Kennedy said out of 10 bids submitted on Wednesday, Hammond Construction, of North Oxford, was the low bidder with $38,053.
The first time the project was advertised, the low bid was $49,000, she said.
The Town Council recently appropriated $62,000 from the stabilization fund to repair the culvert, which is near the Quaboag River. The culvert collapsed after a summer rainstorm, resulting in erosion and encroachment on a neighboring shed.While the area was stabilized with hay bales, that was only a temporary fix.
Said Acting Public Works Department Superintendent Richard P. Kaczmarczyk, "Hopefully we'll get it going in the next few weeks."
The first bid was rejected after the issues with the wood turtle were discovered by the state's natural heritage program during the review process, Kennedy said.
She said this wasn't the first time the wood turtle altered a project in the village of Three Rivers, noting the recent Springfield Street reconstruction.
A "special walkway" under Springfield Street, by the pond near the blueberry farm, was made for them so they could cross the road without getting crushed by cars.
From: HerpDigest Volume # 10 Issue # 47 11/5/10 (A Not-for-Profit Publication)
New Culvert Bids An Cost Savings (for wood turtles)
November 01, 2010, By LORI STABILE
PALMER - The discovery of wood turtles, a state-protected species, near a damaged culvert on Quaboag Street in Three Rivers forced a redesign of the culvert's replacement, but it turned out to be less expensive for the town in the end.
Acting Town Manager Patricia A. Kennedy said out of 10 bids submitted on Wednesday, Hammond Construction, of North Oxford, was the low bidder with $38,053.
The first time the project was advertised, the low bid was $49,000, she said.
The Town Council recently appropriated $62,000 from the stabilization fund to repair the culvert, which is near the Quaboag River. The culvert collapsed after a summer rainstorm, resulting in erosion and encroachment on a neighboring shed.While the area was stabilized with hay bales, that was only a temporary fix.
Said Acting Public Works Department Superintendent Richard P. Kaczmarczyk, "Hopefully we'll get it going in the next few weeks."
The first bid was rejected after the issues with the wood turtle were discovered by the state's natural heritage program during the review process, Kennedy said.
She said this wasn't the first time the wood turtle altered a project in the village of Three Rivers, noting the recent Springfield Street reconstruction.
A "special walkway" under Springfield Street, by the pond near the blueberry farm, was made for them so they could cross the road without getting crushed by cars.
From: HerpDigest Volume # 10 Issue # 47 11/5/10 (A Not-for-Profit Publication)
PALMER - The discovery of wood turtles, a state-protected species, near a damaged culvert on Quaboag Street in Three Rivers forced a redesign of the culvert's replacement, but it turned out to be less expensive for the town in the end.
Acting Town Manager Patricia A. Kennedy said out of 10 bids submitted on Wednesday, Hammond Construction, of North Oxford, was the low bidder with $38,053.
The first time the project was advertised, the low bid was $49,000, she said.
The Town Council recently appropriated $62,000 from the stabilization fund to repair the culvert, which is near the Quaboag River. The culvert collapsed after a summer rainstorm, resulting in erosion and encroachment on a neighboring shed.While the area was stabilized with hay bales, that was only a temporary fix.
Said Acting Public Works Department Superintendent Richard P. Kaczmarczyk, "Hopefully we'll get it going in the next few weeks."
The first bid was rejected after the issues with the wood turtle were discovered by the state's natural heritage program during the review process, Kennedy said.
She said this wasn't the first time the wood turtle altered a project in the village of Three Rivers, noting the recent Springfield Street reconstruction.
A "special walkway" under Springfield Street, by the pond near the blueberry farm, was made for them so they could cross the road without getting crushed by cars.
From: HerpDigest Volume # 10 Issue # 47 11/5/10 (A Not-for-Profit Publication)
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