Snakes guest lecture Flashcards
What is herpetology?
The study of amphibians and reptiles
Are most vertebrates with elongate body forms ectotherms or endotherms?
Ectotherms
What group are snakes derived from?
Lizards
What group encompasses lizards, snakes and amphisbaenians?
Squamata
What is the sister group of squamata? What is the group that includes this and squamata?
Tuatara. Lepidosaurs
What are the 2 reproductive modes of squamates? Which is more common?
Oviparity (egg laying) and viviparity (live bearing). Oviparity is about 80% of cases.
Is viviparity higher or lower as you move away from the equator?
Viviparity is more common farther from the equator
What is the body temperature patterns of pregnant vs non-reproductive females?
Pregnant: relatively high and stable body temp.
Non-reproductive: lower body temp and more variable
What are the 2 leading hypotheses for the evolutionary origin of snakes?
- burrowing
- marine
idk???
Snakes have more vertebrae than any other vertebrae- how many precloacal vertebrae do they have?
120-400 procloacal vertebrae
Give an example of how ectotherms are very temperature resistant?
Could put a snake in the fridge for months and it would regulate its body temperature to fridge temperature and be fine
What is the difference between a lizard eye and a snake eye in terms of lens movement?
Lizard eyes focus like other vertebrae lenses- contracting muscles on either side to change shape of lens
Snake eyes move the lens instead
How good are snake eyes?
Don’t have great vision, but can see movement very well
What kind of ears do snakes have?
Snakes have no external ears, simplified ear drums
What frequency is the snake auditory system most sensitive to?
Low frequency
Is there evidence of communication between different snakes?
No
What are the 3 chemosensory systems in snakes?
- Gustation (limited, no taste buds on tongue)
- Olfaction (nasal)
- Vomerolfaction (picks up larger molecules on forked tongue)
The main thermosensory organ does infrared vision- What does this detect?
Detects endothermic prey- sometimes call this “vision” because it constructs an integrated picture with the eyes
What is an adaptation of pit vipers?
Have pits on the side or the jaw, or nerve endings here. Gives them binocular vision in the infrared. The membranes are thermosensitive
Why did researchers blindfold snakes?
To see if they could catch a target without eyesight- they could!!!
What do the ventral scales of snakes do?
Enhance slippery-ness
What is an anatomical consequence of a long and limbless body?
Paired organs are sequential, not side by side (right before left)- right organ is usually bigger.
- in highly derived snakes, left lung is actually lost
What is a consequence of a long limbless body that relates to feeding?
Must swallow prey whole- can either eat lots of small prey or a few large prey
What is the main thing about the group of snakes “macrostomata”?
Snakes that eat large prey- big mouth
