Amphibia 2

Amphibia 2 - sometimes for many days. When she lays her...

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Amphibia 2 On land a frog can progress by a series of leaps, propelled by its powerful hind legs* A toad can also jump but usually moves by crawling* * After James Gray Locomotion Life cycle Toads and some frogs spend the winter by hibernating on land, in holes in the ground. Some frogs hibernate in the mud at the bottom of ponds. In Spring, frogs and toads migrate to the pond in which they developed. Here, they lay eggs. Fertilisation is external but there is a behaviour pattern which ensures that the eggs are fertilised as soon as they are laid. The male frog or toad mounts on the back of a female, gripping her under the arms with his forelegs. In this way, he is carried around in the water by the female,
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Unformatted text preview: sometimes for many days. When she lays her eggs, the male releases sperm which fertilises them On contact with the water, a coating of jelly round the eggs swells up and the eggs (spawn) float to the surface. The jelly reduces the chances of the eggs being eaten by predators. jelly layer egg Frog spawn forms clumps Toad spawn forms strings Changes taking place 4-5 days after laying (a) (b) (c) (d) (a) Small sphere consisting of 2 or 3 layers of cells (b) Elongates (c) Tail and head distinguishable (d) External gills forming. Wriggling in the jelly; ready to emerge © D.G. Mackean Newts lay their eggs singly...
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This note was uploaded on 11/29/2011 for the course BIO 218 taught by Professor Young during the Fall '11 term at BYU.

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