Lesson 16 - Turtles Flashcards
turtles
- Phylogeny has been a mess
- Was a lot of uncertainty
- Turtles are a sister group to the archosauria
- Turtles are anapsid
——They come from an ancestral stock that was anapsids
——-Or they are diapsids and have lost the feature
Molecular data + a diapsid skull
—–Conforms their diapsid condition in the phbylogeny
We now have fossils of very ancient turles that are diapsid
Shell itself is not bone
- Skeleton is beneath the shell
- Ribs form the underlying of the shell
- Ribs are external to the girdles
———Not true for another vertebrates
——–Ours are medial to the pectoral and pevlic girls
——Ribs are fused
——Intercostal ventilation requires the ribs to be flexible
^^^^ how do they breath
——–Lungs are attached ventrally
———Viscera is moved upward by the contraction of the ()
———-Whole different set of muscle axton for ventilating the lungs
————Some turtles (aquatic) exchange gas through their cloaca
turtle heart
- Lacks a ventricular septum
- The blood flow coming in is a mixture of oxygenated and deoxygenated blood that is partially kept separate due to the pressure changes, but not by that much
aquatic taurus
-Spend a long time underwater
- Efficient to send blood to lungs
- They shunt the blood when they dive
——-Normally blood flows right through pulmonary artery
——-But when turtle is in dive mode – it shuts it directly to the aortic arch
——–Saves energy by rerouting it to a lung that is not in use
ancient turtles
- Very similar to derived turtles
- High arched shell
- Boney plastron
- Presence of a trochlear process – (((unique))))
- Function of this is how we differ
^^ acts as a pulley
cryptodires
retract head by bending vertebae straight back - horizontally
pleurodires
- retract by bending vertebra vertically
differnt morpholody from 12 thousand years ago
- ## height of dome affects the ecological behavior
ecology and behavior of turtles – temperature regulation
- Ectotherms
- Bask in sun
- Some bask to remove leeches
- Thermal inertia
- Marine species of turtles have countercurrent heat exchange in their flippers
social behavior
- Stripes on head determine species recognition
- Some would use fecal pellets as markers for their territory
- Some — raising head signals dominance
Males smaller??
sex determination
- Instead of chromosomes determining sex → many if not most have temperature sex determination → the temp at which the egg incubators determines sex
- In nature you’re not gonna get a perfectly constant temp → why the cycles are important to demonstrate
- Because you would expect the eggs to experience the same environment → nests tend to be exclusively male and exclusively female
mechanism for sex determination
- Reared turtles at different concentrations of estrogens ( know that there would be different levels as different temperatureS)
Measured the estrogen dosage (measured 3 of them) - At very low injected levels, there were almost no females produced
- At only .05 g of estriol – huge increase in female population
- In the other groups – mostly all females
- Probably a higher temperature drove in those turtles an increase in estrogen
what does the turtle experiment suggest
– Effects of what temperature has on their own estrogen levels affects the sex
—-When hormones are biosynthetically produced → enzymes are temperature dependant
— Aromatase catalyzes the reaction from testosterone to estrogen
—-Higher temperatures cause higher activity levels of aromatase → giving rise to the female numbers
Loman research
Loggerhead sea turtles
Mass emergence helps survival of majority of turtles
navigation of migration
- Role of visual cues
- First turtle has to emerge from ocean and make its way to the ocean
- Then have a many year migration in the caribbean and south atlanti
- How do they navigate?
