testudines
turtles, latin for tortoise (shell)
sister lineage to archosauria
361 extant species
14 families
turtle skeleton structure
beta keratin forms outer layer of horny scutes
inside is lateral extensions of ribs
limbs inside ribs
extant groups of turtles
cryptodires and pleurodires
cryptodires
“hidden neck”
1 of 2 extant groups of turtles
11 families and 262 species
widely distributed
pleurodires
“side neck”
1 of 2 extant groups of turtles
3 fmailies and 99 species
S hemisphere
turtle respiration differences between other amniotes
not able to ventilate with same mechanism as other basal amniotes (ex. movement of rib cage to draw air into lungs - ribs are fused to shell)
lungs attach to the carapace dorsally and laterally
how do turtles respire?
contract muscles to increase vol of visceral cavity, expands lungs and air moves in
contract other muscles to decrease volume, compress lungs and air move out
cloacal respiration in turtles
in at least one species, the cloaca is lined with sacs with highly vascularized lining. turtles pump water into and out of cloacal sacs
adaptations of respiration in turtles
lung resp is complemented by pharyngeal and cloacal resp
pharyngeal respiration of turtles
when confined underwater, they draw water into mouth/pharynx. have flat topped highly vascularized papillae
how does blood flow occur in turtles
incomplete septum between ventricles, flow of blood is controlled partly by relative resistance to flow in each circuit
how do turtles regulate temperature
endothermy and ectothermy
reproduction in turtles
all oviparous, internal fertilization
temperature dependent sex determination
little parental care
