10. Amphibians

Question 1

Amphibia

Answer 1

around 8.000 species extant

Freshwater. A few species live in brackish water, mix of salt and freshwater.

Question 2

Key characteristics of Lissamphibia

Answer 2

Repreduction
Amplexus, a special form of mating.
Aquatic eggs
Three-chambered heart
Glans
Respiration through mouth and skin
Teeth (normally none)

Question 3

Reproduction

Answer 3

Frogs and toads use external fertilization

Salamanders and caecilians use mostly internal. They have cloaks, where the male will put sperm on a leaf and the female will pick it up.

Most of the species are oviparous (lay eggs), but some ovoviviparous and viviparous.
- Intraauterine cannibalism, like we know some sharks do. Or they eat other nutrients provided by the mother

Question 4

Amplexus

Answer 4

A way of matting where the males pile on top of a female to get the best position to fertilize the eggs.

Sometimes there can be 5 males on top of one female.

Question 5

Small aquatic eggs

Answer 5

Works like fish eggs.

Gas exchange and removal of waste by diffusion into the water.

Again the amphibian would die if there is no water around it.

Question 6

The amphibian egglayers.

Answer 6

Layers of jelly on the outside

Inner layers

Vetielline membrane (chorion)

Perivitelline chamber

Ovum (embrame)

Yolk

Question 7

Why do amphibians produce so many eggs.

Answer 7

Smart thing with putting them together, is that the predator can´t eat all of them in one time. The same thing with the wilderbeast at the african savana. They get all their young at one time, so lions other predetors can´t eat all of them at once. Defencemechanism.

Question 8

The evolving of a frog.

Answer 8

The development from larvae to adult. They start with gills to respire, where after they develop lungs.

Some modern species doesn´t follow the pattern.