Vertebrates 3 - Reptiles

3 ways reptiles got out of water

• more efficient heart/circulatory system

• amniontic egg

• excretory system

type of phylogentic group of reptiles

paraphyletic

skin evolution

waterproof b-keratin skin

helps them conserve water so they can live in hot dry environments like deserts

Reptile Circulatory System

‘4 chambered heart’ with an alternative circuit

blood can be shunted to the respritory surfaces (lungs) for when pressursized blood is needed (out of water)

OR if not needed…that valve closed and blood is just pumped to body for when they go back underwater

Turtles/Snakes/Lizards vs Crocodillian circulatory system

partially divded ventricle vs fully divided

External Shell of Amniotic Egg

• made up of extra embryotic membranes

• leathery and brittle (CaCO2)

• permeable to gases (O2 and CO2)

• fairly impermeable to water but can’t be layed submerged in water forever

• not present in therian mammals (humans)

Reproduction

**bc terrestrial egg, sperm can penetrate

• internal fert…the shell and albumen are formed in females oviduct

nitrogenous wastes

product of protien and DNA metabolism

• ammonia, urea, uric acid

Ammonia NH3

very soluable in water, very toxic

need to be diluted or disposed of quickly or converted to less toxic form

used by rayfinned fish, aquatic inverts, larval amphibians

Urea

soluable in water, medium toxicitiy, needs less water for disposal

used by cartilagenous fish, adult amphibians, and mammals (humans)

Uric Acid

• insoluable in water *hard for cleaning car

• non toxic

• little water needed for disposal

*all traits perfect for amniotic egg

used by insects, birds, and reptiles

Kidney Func and Process

regulate levels of water and dissolved solutes in blood and filter to form urine

squeeze everything out (to bowmans capsule) and then reabsorb what you still need

Testudinia (Turtles and Tortoises)

changed very little over evolutionary time

dorsal shell is expansion of ribs

mostly aquatic (some terrestrial)

humans exploit result in pop declines

Crocodillia

spend much time in water

build nests on land or floating piles of veg

Lepidosauria who and traits

include tuatara and squamates

horny scales

gas exchange only through lungs

Tuatara

resemble lizards…only 2 species survived

found in NZ only

have no external ears, nocturnal, well developed third parietal eye (light sensitive - help w carcadian rhythm)

Squamates

mostly lizards and highly diverse

32 events where some lost legs and became snakes!

Snakes 

no limbs

200+ vertebrates

highly kinetic skull

vomeronasal organ (smelling tongue)