Modern Amphibians

Question 1

What is the importance of amphibians having thin skin?

Answer 1

Cutaneous respiration require thin moist skin for gas transfer

Question 2

What two glands are common in amphibians?

Answer 2

Mucous glands: secrete mucous for cutaneous respiration

Granular glands: secrete poisonous alkaloid compounds for defense

Question 3

Why do most terrestrial amphibians have more keratin in their skin?

Answer 3

helps prevent dessication

Question 4

___ teeth are unique to modern amphibians and some temnospondyls

Answer 4

Pedicellate

- tooth has uncalcified dividing base from crown of calcified dentin

Question 5

What order consists of the frogs and toads?

Answer 5

Order Anura

Question 6

What are some defining characteristics of the Anurans? (frogs and toads)

Answer 6

• paired limbs
• no tail in adults
• jumpers
• tympanum usually present to transmit sound to inner ear
• external fertilization (mostly)

Question 7

What are some features of the Anurans’ skull?

Answer 7

• flattened, open
• big jaws, reduced palate which allows eyeballs to drop into oral cavity when swallowing
• hyomanibula becomes stapes

Question 8

What’s the functional significance of the eyeballs having the ability to drop into the oral cavity when swallowing?

Answer 8

• protects eyeballs

- helps push food down while swallowing

Question 9

T or F: the axial skeletons of anurans is highly specialized

Answer 9

True

• shorter vertebral column (9 or less vertebrae)
• atlas&skull junction forms movable joint through two condyles
• post sacral vertebrae fused into rod-shaped urostyle between two elongated illium bones of pelvic girdle

Question 10

What are some features of the anuran’s appendicular skeleton?

Answer 10

• robust pectoral girdle and fused radius/ulna absorb shock of landing
• tibia/fibula fused for sturdiness
• increased length of hind limbs for jumping

Question 11

What animal is in the order Caudata

Answer 11

salamanders

Question 12

-what are some defining characteristics of the order caudata? (salamanders)

Answer 12

• long tail, paired limbs
• suction feeding in water, projectile tongue on land
• no tympanum
• external or internal fertilization

Question 13

What are some features of the skeleton of caudata?

Answer 13

• long back, 10-60 pre-sacral vertebrae
• flattened, open skull, large orbits
• lots of cartilage, poor ossification
• reduction and loss of bones is common

Question 14

What type of locomotion do salamanders use?

Answer 14

• dual locomotion
• use short limbs for walking and tail for swimming
• each controlled by distinct sets of neurons in brainstem

Question 15

What vertebrate is part of the order Gymnophiona?

Answer 15

Caecilians

Question 16

What are some defining characteristics of the order gymnophiona? (caecilians)

Answer 16

• no limbs or girdles
• solid and compact skull for burrowing
• tropical habitats
• internal fertilization, hatchlings aquatic or terrestrial
• 60-285 trunk vertebrae, tail short or absent

Question 17

What are some features of the caecilian’s skull/head?

Answer 17

• skull used as digging tool
• eyes reduced
• paired tentacles in front of head help with chemosensation in dark tunnels

Question 18

What is paedomorphosis?

Answer 18

-when the larval characteristics of ancestors appear in adults of descendants

Question 19

What is heterochrony?

Answer 19

-changes in the timing and rate of developmental events between ancestors and descendants