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Flashcards in Zoology Final b Deck (35)
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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



acts as a "shock absorber" to protect fetus
- creates aquatic environment



- vascularized
- contains blood vessels
- used for gas exchange and storage of nitrogenous waste


yolk sac

contains food for the embryo



enclose the other membranes



- the membrane of fused chorion and allantois
- membrane functions in gas exchange through porous eggshell



- 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