Truly is the turtle an amazing animal

[redbird]

We got to wondering about phylogenetic relationships, and after a while I got to this:

Turtles belong to the reptilian grade of physiological organization. They are ectothermic and have relatively low metabolic rates. Being ectotherms, their body temperature remains close to the temperature of their environment, and they are entirely reliant on external sources of heat. Many turtles bask in the sun to raise their body temperature to a point where bodily functions can operate optimally. One species, the leatherback, can maintain a body temperature above that of its environment, but how this is achieved is yet to be determined. Most turtles cannot be active during very hot or very cold periods. Therefore, hibernation in winter and aestivation in summer is common for members of this group.

Turtles breathe with lungs located inside of a rigid ribcage. They therefore must use a different mechanism for breathing than most vertebrates. Muscles in the region of the leg pockets act to inflate the lungs, muscles on the surface of the lungs dorsally and ventrally deflate them. Many turtles augment gas exchange at the lungs with gas exchange in the throat or in the cloaca.

In addition to providing protection for the turtle, the shell of at least some species has an important physiological function. It acts as a "calcium bank". Calcium and other cations are taken from the carapace and plastron to buffer the blood during hibernation when metabolic acids are likely to build up. In other species, it appears that in reproductively active females, calcium is removed from the shell and incorporated into eggshells forming around follicles in the oviducts.

Comments

[callunav.livejournal.com]

They also can't absorb calcium from their diet without access to UVB light.

Someday, I should introduce you to Freddy. Of course, she's not ever going to use her calcium for egg-laying, because she's male. But she's very nifty.

[klingonlandlady.livejournal.com]

as exchange in the throat or in the cloaca

Am I understanding you to say they can breathe thru their ass?

[redbird]

cattitude asked much the same thing. It appears that some can, though not all.