Snakes guest lecture

Question 1

What is herpetology?

Answer 1

The study of amphibians and reptiles

Question 2

Are most vertebrates with elongate body forms ectotherms or endotherms?

Answer 2

Ectotherms

Question 3

What group are snakes derived from?

Answer 3

Lizards

Question 4

What group encompasses lizards, snakes and amphisbaenians?

Answer 4

Squamata

Question 5

What is the sister group of squamata? What is the group that includes this and squamata?

Answer 5

Tuatara. Lepidosaurs

Question 6

What are the 2 reproductive modes of squamates? Which is more common?

Answer 6

Oviparity (egg laying) and viviparity (live bearing). Oviparity is about 80% of cases.

Question 7

Is viviparity higher or lower as you move away from the equator?

Answer 7

Viviparity is more common farther from the equator

Question 8

What is the body temperature patterns of pregnant vs non-reproductive females?

Answer 8

Pregnant: relatively high and stable body temp.

Non-reproductive: lower body temp and more variable

Question 9

What are the 2 leading hypotheses for the evolutionary origin of snakes?

Answer 9

• burrowing
• marine
  idk???

Question 10

Snakes have more vertebrae than any other vertebrae- how many precloacal vertebrae do they have?

Answer 10

120-400 procloacal vertebrae

Question 11

Give an example of how ectotherms are very temperature resistant?

Answer 11

Could put a snake in the fridge for months and it would regulate its body temperature to fridge temperature and be fine

Question 12

What is the difference between a lizard eye and a snake eye in terms of lens movement?

Answer 12

Lizard eyes focus like other vertebrae lenses- contracting muscles on either side to change shape of lens
Snake eyes move the lens instead

Question 13

How good are snake eyes?

Answer 13

Don’t have great vision, but can see movement very well

Question 14

What kind of ears do snakes have?

Answer 14

Snakes have no external ears, simplified ear drums

Question 15

What frequency is the snake auditory system most sensitive to?

Answer 15

Low frequency

Question 16

Is there evidence of communication between different snakes?

Answer 16

No

Question 17

What are the 3 chemosensory systems in snakes?

Answer 17

• Gustation (limited, no taste buds on tongue)
• Olfaction (nasal)
• Vomerolfaction (picks up larger molecules on forked tongue)

Question 18

The main thermosensory organ does infrared vision- What does this detect?

Answer 18

Detects endothermic prey- sometimes call this “vision” because it constructs an integrated picture with the eyes

Question 19

What is an adaptation of pit vipers?

Answer 19

Have pits on the side or the jaw, or nerve endings here. Gives them binocular vision in the infrared. The membranes are thermosensitive

Question 20

Why did researchers blindfold snakes?

Answer 20

To see if they could catch a target without eyesight- they could!!!

Question 21

What do the ventral scales of snakes do?

Answer 21

Enhance slippery-ness

Question 22

What is an anatomical consequence of a long and limbless body?

Answer 22

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

Question 23

What is a consequence of a long limbless body that relates to feeding?

Answer 23

Must swallow prey whole- can either eat lots of small prey or a few large prey

Question 24

What is the main thing about the group of snakes “macrostomata”?

Answer 24

Snakes that eat large prey- big mouth

Question 25

What are the 3 main prey capture methods?

Answer 25

• grab and swallow
• constriction
• venom via fangs

Question 26

What are the 2 main functions of a snake’s venom apparatus?

Answer 26

• killing and digesting prey

- defense

Question 27

What are 3 adaptations for swallowing prey?

Answer 27

• cranial kinesis
• elastic skin
• trachea opening in mouth