Biology...5.6.9. Describe...?

Question

5. Describe the life history and reproduction of the common toad.

6. Why are hens' eggs very satisfactory for the study of embryology?

9. Describe the development of the rabbit embryo from fertilization to birth.

Answer 1

TOAD ---- Although the adults spend most of their time on land the females enter ponds and other still waters to lay their eggs, toadspawn, which can be distinguished from the spawn of the common frog as it forms strings rather than a large mass of eggs. Eggs are laid in the spring, with the females attempting to return to the water in which they were born. The young tadpoles resemble other tadpoles in their appearance except that toadpoles have a larger, rounder blacker head and shorter tail.

A tadpole (also known as a pollywog or polliwog) is a larval amphibian, the first stage of a frog or toad.

During the tadpole stage of an amphibian's life cycle, the tadpole breathes by means of external or internal gills. They do not have arms or legs until later stages in their lives, and has a fin-like tail with which it swims by lateral undulation, similar to most fish. As a tadpole matures, it metamorphoses by gradually growing limbs and then (in the case of frogs) absorbing its tail by apoptosis. Lungs develop around the time of leg development, and tadpoles will often swim to the surface of the water to breath air. During the final stages of metamorphosis, the tadpole's mouth must change from a small round mouth at the front of the head, to a large mouth the same width as the head. The intestine will shorten to accommodate the frog's carnivorous diet.

Most tadpoles are herbivorous, subsisting on algae and plants. Some species are omnivorous, eating detritus and, whenever available, other tadpoles

Eggs are cheap,readily available,abundant and because of their short gestation period they are more useful in study of embryology

Rabbit is a mammal.so i think you can go through mammalian embryogenesis to know about rabbit's embryo.

hope it helped