Editing Reptile (section)

====Turtles and tortoises====
[[File:Tortue de Floride Amiens.jpg|thumb|[[Red-eared slider]] taking a gulp of air]]

How [[turtle]]s breathe has been the subject of much study. To date, only a few species have been studied thoroughly enough to get an idea of how those turtles [[Breathing|breathe]]. The varied results indicate that turtles have found a variety of solutions to this problem.

The difficulty is that most [[turtle shell]]s are rigid and do not allow for the type of expansion and contraction that other amniotes use to ventilate their lungs. Some turtles, such as the Indian flapshell (''[[Indian flapshell turtle|Lissemys punctata]]''), have a sheet of muscle that envelops the lungs. When it contracts, the turtle can exhale. When at rest, the turtle can retract the limbs into the body cavity and force air out of the lungs. When the turtle protracts its limbs, the pressure inside the lungs is reduced, and the turtle can suck air in. Turtle lungs are attached to the inside of the top of the shell (carapace), with the bottom of the lungs attached (via connective tissue) to the rest of the viscera. By using a series of special muscles (roughly equivalent to a [[thoracic diaphragm|diaphragm]]), turtles are capable of pushing their viscera up and down, resulting in effective respiration, since many of these muscles have attachment points in conjunction with their forelimbs (indeed, many of the muscles expand into the limb pockets during contraction).<ref>{{cite journal |first1=Tyler R. |last1=Lyson |first2=Emma R. |last2=Schachner |first3=Jennifer |last3=Botha-Brink |first4=Torsten M. |last4=Scheyer |first5=Markus |last5=Lambertz |first6=G.S. |last6=Bever |first7=Bruce S. |last7=Rubidge |first8=Kevin |last8=de Queiroz |year=2014|title=Origin of the unique ventilatory apparatus of turtles |journal=Nature Communications |volume=5 |number=5211 |page=5211 |doi=10.1038/ncomms6211 |doi-access=free |pmid=25376734 |bibcode=2014NatCo...5.5211L |url=http://www.zora.uzh.ch/id/eprint/100716/7/LysonEtAl_NatCommun2014_Vol5_OriginVentilationApparatusTurtles_Supplem_s1.pdf}}{{open access}}</ref>

Breathing during locomotion has been studied in three species, and they show different patterns. Adult female green sea turtles do not breathe as they crutch along their nesting beaches. They hold their breath during terrestrial locomotion and breathe in bouts as they rest. North American box turtles breathe continuously during locomotion, and the ventilation cycle is not coordinated with the limb movements.<ref name=Landberg>{{cite journal | last=Landberg | first=Tobias |author2=Mailhot, Jeffrey |author3=Brainerd, Elizabeth | title=Lung ventilation during treadmill locomotion in a terrestrial turtle, ''Terrapene carolina'' | journal=Journal of Experimental Biology | volume=206 | issue=19 | year=2003 | pages=3391–3404| doi=10.1242/jeb.00553| pmid=12939371| doi-access=free | bibcode=2003JExpB.206.3391L }}</ref> This is because they use their abdominal muscles to breathe during locomotion. The last species to have been studied is the red-eared slider, which also breathes during locomotion, but takes smaller breaths during locomotion than during small pauses between locomotor bouts, indicating that there may be mechanical interference between the limb movements and the breathing apparatus. Box turtles have also been observed to breathe while completely sealed up inside their shells.<ref name=Landberg/>