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Name: Craig
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Question:
A student just brought a mother toad into our classroom. She has the toad in a mixing bowl with thousands of eggs and about a pint of pond water. Are these eggs fertilized? Do they become fertilized in the female or after they are layed? Can we watch them develop in our classroom? Is there any special water, lighting, temperature, or plants I should include?



Replies:
My recollection is that, during mating, eggs are effectively "squeezed" from the female by the "grip" of the male, and fertilization occurs as the eggs emerge from the female. i.e., sperm from the male are released by the male onto the eggs. Depending upon how the eggs/toad were obtained, there is a good likelihood that the eggs were fertilized when the female released them.


Yes, you should be able to observe their development. I once raised a frog in similar circumstances... eggs were removed from a female in a lab, fertilized by sperm from a male (removed in the lab), and then, placed together in a petri dish. the resulting tadpole grew eventually into a frog. The tadpole was kept in an aquarium and provided with air via the normal aquarium pumps. For the diet of a tadpole/toad, you can search the web. My recollection, surprisingly, was that as the tadpole developed, I actually observed it consuming waste from the tropical fish kept in the same aquarium!

Good luck, and thanks for using NEWTON!

Dr. Rupnik



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