Zoology Final b Flashcards
types of reptiles
- snakes
- turtles
What made possible the complete conquest to land?
development of an amniotic egg that can be laid away from water - finally severed the ties to aquatic reproduction
characteristics of amniotic egg
- eggshell enclosing series of membranes which include: amnion, allantois, yolk sac, chorion and chorioallantoic
amnion
acts as a “shock absorber” to protect fetus
- creates aquatic environment
allantois
- vascularized
- contains blood vessels
- used for gas exchange and storage of nitrogenous waste
yolk sac
contains food for the embryo
chorion
enclose the other membranes
chorioallantoic
- the membrane of fused chorion and allantois
- membrane functions in gas exchange through porous eggshell
amniotes
- monophyletic group of tetrapods that have amniotic egg
- include: reptiles, birds and mammals
extant reptiles
- crocodilians
- lizards
- snakes
- turtles
- tuataras
extinct reptiles
- dinosaurs
- mesosaurs
- plesiosaurs
- pterosaurs
reptilian skin
have tough, dry clay skin which offers protection against desiccation and physical injury
- waterproof
reptile scales
- reptilian scales are derived from epidermis of skin and formed largely of keratin
- not homologous to fish scales, which are bony, dermal structures
- homologous to scales on legs of birds, and the farther of birds which develop from scale-like structures
reptile jaws
- designed for quick closure but cannot exert much force once prey is captured
- efficiently designed for applying crushing or gripping force to prey
snake and lizard jaw
- kinetic skull with moveable quadrate bone
- enables upper jaw to be raised independently thus increasing the effective closing force of jaw musculature
- enables them to “unhinge” jaw
- considered major factor in diversification and ecological success of these animals
reproduction in reptiles
- have internal fertilization necessitating some form of copulatory organ
- internal fertilization is necessary so that egg is fertilized before the eggshell is added
circulatory system in reptiles
- have higher blood pressure and in general is more efficient
- have incompletely 4-chambered heart (not fully formed septum)
respiratory system in reptiles
- lungs are better developed, no need for cutaneous respiration through skin
- air sucked into lungs rather than pushed
- no true diaphragm
- create negative pressure by expanding rib cage when they breathe
reptilian advances
- more efficient kidney for water conservation, enabling them to live in dry environments
- considerably more advanced nervous system with first true cerebral cortex - more complex behavior
ancient reptiles
- turtles
- virtually unchanged during 200 million years of evolutionary history
- shell formed from ribs and vertebrae - inner bony layer and out keratin
life history of turtles
- apparently can live more than 150 years due to relatively low metabolism
- may secede 1598 pounds
- very few sea turtles reach extreme size because they are heavily exploited
- many endangered or threatened
sense in turtles
- hearing, virtually silent except during mating
- good sense of smell
- excellent eyes color perception is as good as it is in humans, allowing them to catch prey quickly and accurately
difference between turtle, tortoise and terrapin
- turtle > webbed-feet
- tortoise > stumped feet
- terrapin > mixture of webbed-feet and stumped feet
characteristics of snakes
- possess heat-sensitive pit organs that are so sensitive they can detect prey in total darkness, up to .003 degree change
- special muscles erect hollow fangs when they bite
- venom gland produces venom
senses of snakes
- tongue picks up scent, then drawn across Jacobson’s organ in roof of mouth which does the actual smelling
- have internal ear bones
- can sense vibrations but may not be actually able to hear
characteristics of lizards
- very diverse
- 5000 species
- extremely keen eyesight
- can see some UV light
sex determination in komodo dragons
- ZW sex determining system, males are ZZ
- ovum determines the sex
- capable of parthenogenesis if no males are around
- females lay unfertilized eggs and the Z chromosome just doubles > so no fertilization
characteristics of tutara
- endemic to New Zealand
- most recent common ancestor is lizards and snakes
- up to 30 in. long, spiny crest along back
- living fossils
characteristics of crocodilians
- mostly unchanged for 200 million years
- 4-chambered heart
- devoted parents that care for young after hatching
- mother responds to vocalizations of hatchlings and helps them break out of nest, then carries them to safety
- crocodile is endangered
- alligator is threatened
sex determination in crocodilians
- temperature of the nest determines the sex
- male > 88 degrees
- female < 88 degrees
difference between alligator and crocodile
- alligators are mainly freshwater and have a rounded nose
- crocodiles are both freshwater and seawater and have a more pointed nose
reptile survival
- severe decline due to habitat loss and poaching
- many endangered and threatened species
two major groups of dinosaurs
- saurischians
- ornithischians
- dominated earth
- differ in way the pelvis sits
saurischians
lizard-hipped
ornithischians
bird-hipped
