20 - Reptiles Flashcards
Are birds reptile?
Yes
How do you get away from water?
- More efficient heart
- Amniotic egg (so it doesn’t dry out)
- Better excretory system (nitrogenous waste)
3 major groups in reptilia?
- Lepidosauria (lizards, snakes)
- Testudinia (turtles)
- Crocodilia
Characteristics that make reptiles truly terrestrial?
- More efficient heart
- Breath via lungs only
- Must conserve water (skin waterproofed by keratin, produce special nitrogenous waste - uric acid)
- reproduce + develop on land (internal fertilization + amniotic egg)
Reptilian hearts are more … than amphibians’
Separated
Birds and mammals have …… pulmonary and systemic systems
Completely separated
What is the amniotic egg?
An egg surrounded by extra-embryonic membrane
Characteristics of the external shell of the amniotic egg?
- Leathery or brittle (CaCO3)
- Permeable to gases (O2 & CO2)
- Fairly impermeable to water
- Not present in therian mammals
Consequences of a terrestrial egg?
1) internal fertilization (sperm cannot penetrate egg shel - shell & albumen added to fertilized egg in female’s oviduct)
2) Non-toxic nitrogen waste product required (= uric acid)
Excretory products?
- Salts, ions (by skin, gills, kidneys, glands)
- Water
- Fecal matter
- Nitrogenous wastes (product of protein & DNA metabolism, released by excretory organs - kidneys - and skins and gills)
Nitrogenous wastes come from…
- Carbohydrates
- Fats
- Proteins
- Nucleic acid
Nitrogenous wastes become…
- Ammonia
- Urea
- Uric acid
Who has ammonia as nitrogenous waste?
- Ray-finned fish
- Aquatic inverts
- Larval amphibias
Characteristics of ammonia
- Very soluble in water
- Very toxic
- Needs to be diluted and disposed of quickly (or converted to less toxic form - urea or uric acid)
Who has urea as nitrogenous wastes?
- Cartilaginous fish
- Most adult amphibians
- Mammals
