Amphibians

Question 1

Define ontogeny.

Answer 1

Organism lives on water or on land at different stages of development.

Question 2

Describe the skin of amphibians.

Answer 2

Smooth and moist.

Absence of keratinised scales (except in caecilians)

Mucous glands (prevent desiccation/slippery/disease-free)

Poison glands

Question 3

Name the different types of respiration in amphibians.

Answer 3

1) cutaneous - gas exchange occurs across the moist skin
2) Buccopharyngeal - gas exchange occurs in buccal cavity/pharynx
3) Pulmonary - gas exchange occurs in paired lungs (too small for all gas exchange)
4) Gills - only larval forms and neotenics

Question 4

Name the three specialised auditory structures and what they do.

Answer 4

1) Papilla amphibiorum - sensory structure in the inner ear that detects low frequencies
2) Papilla basilaris - allows detection of high frequencies
3) Operculum columella complex - increases the transmission of sound to the inner ear

Question 5

Name two features in the eye and what they do

Answer 5

1) Green rods - a cell that allows for better detection of green light
2) Levator Bulbi - muscle that bulges the eye outward

Question 6

Define pedicellate teeth.

Answer 6

They have a narrow band of uncalcified dentine that in the middle of the teeth that makes them flexible.

Question 7

In what ways are frog tad-poles fish like? (3)

And how do they change? (4)

Answer 7

1) tail
2) gills
3) lateral line system

1) reabsorption of the tail
2) limbs
3) development of eyelids
4) restructuring of the larval skull and hyobranchial apparatus

Question 8

Name the three orders in amphibia

Answer 8

1) Anura
2) caudata
3) Gymnophiona

Question 9

Many ______________ are paedomorphic.

Answer 9

Salamanders

Question 10

Explain the problems of adapting to terrestrial life.

Answer 10

1) water is much denser than air - a dense medium helps to support the weight of the animal, whereas air doesn’t provide the same support. They had to develop new methods of locomotion (saltatorial in frogs + development of legs).
2) sense organs had to be adapted to life on land. The inner ear is a fluid environment and it takes more energy to transmit sound through fluid than air. So there has to be a mechanism to amplify force before it can be transmitted to the inner ear.
3) respiratory respiration
4) fluctuation in ambient temperature
5) water loss