Lecture 22 Reptiles Flashcards
3 major innovations in reptiles to live on land
- More efficient heart
- Amniotic egg
- Better excretory system
Describe reptiles terrestrial chara.
- More efficient heart
- Breathe via lungs only
- Must conserve water
- skin is waterproofed by ß-”keratin”
- produce a special nitrogenous waste (uric acid)
- Reproduce & develop on land
- internal fertilization
- amniotic egg
- Of course, some spend almost all of their time in the water (e.g., sea snake)
Comparison of CS btw fish, amphibians and reptiles (exlude birds)
Compare heart of heart btw reptiles and mammals
-human fetuses also have a series of “shunts”
-similar “shunts” are sometimes present after birth and need to be corrected surgically
Describe innovation of amniotic egg in Reptalia
Consequence
* internal fertilization
– sperm cannot penetrate egg shell
– shell & albumen are added to the fertilized egg in the female’s oviduct
* non-toxic nitrogen waste product is required = uric acid
Describe excretory products
Describe 3 types of nitrogenous wastes
- ammonia (NH3)
* very soluble in water
* very toxic
* needs to be diluted & disposed of quickly or converted to a less toxic form
Who? ray-finned fish (marine & fresh), aquatic inverts (marine & fresh), larval amphibians - urea
* soluble in water
* medium toxicity
* less water needed for disposal relative to ammonia
Who? cartilaginous fish, most adult amphibians, mammals - uric acid
* insoluble in water
* not toxic
* little water needed for disposal
Who? insects, reptiles, birds
Vertebrate excretory organ = kidney
function = to regulate levels of water & dissolved solutes in blood (“filter the blood”) & to form urine
Describe excretory organ and its function
Vertebrate excretory organ = kidney
function = to regulate levels of water & dissolved solutes in blood (“filter the blood”) & to form urine
Describe non-avian reptiles (Testudinia Archosaurs Lepidosauria)
- ~ 6,000 species
- mostly terrestrial
- carnivores, herbivores, omnivores
- dry skin, scales
- first amniotes
– arose during Carboniferous~300mya
Describe Testudinia (turtles and tortoises)
- have changed very little in the past 250 million yrs.
- The dorsal and ventral bony plates form a shell. Dorsal shell is an expansion of the ribs.
- Most are aquatic, some terrestrial. Sea turtles come ashore to lay eggs.
- Human exploitation has resulted in declining populations—all are now endangered
Describe Crocodilia (aka Archosaurs)
Crocodilians = crocodiles, caimans, gharials, and alligators spend much of their time in water. They build their nest on land or floating piles of vegetation. All are carnivorous.
Describe Lepidosauria (Lizards, snakes, Tuataras, Amphisbaenia)
Squamates: incl. lizards and snakes
Tuataras – resemble lizards have several different characters; only two species survive.
All have skin covered with horny scales.
Gas exchange is only through the lungs.
Describe Tuataras
- NZ only – endangered
- no external ears
- nocturnal
- well-developed parietal eye (also found in other groups)
Describe lizards
- Highly diverse
- Some have lost their legs (~32 separate events) - a few of many cases in squamates
- Komodo dragon gets to 3 m long
Describe Amphisbaenia
- limb girdles much reduced.
– no legs except in Bipes - eyes are reduced, no ear opening
- scales fused into rings (annuli) encircling the body
