-
Asked by madscientist101 to Aime, Akshat, Diana, Gemma, Judith on 16 Jun 2011.
-
Judith McCann answered on 16 Jun 2011:
Most fish are egg-layers, the eggs contain half the mother DNA and are not developed yet, so are quite small. Again for most kinds of fish the fertilization of the eggs happens outside the bodies of either gender, in the water around them. There are very few kinds but some fish can live bear, this mean that fertilization and development of the eggs happens inside the fish-they have placentas and provide the baby fish with oxygen in a similar way to people.
Sorry, I really don’t know anything about insects, I’ve never really thought about it. Hopefully one of the other scientists can answer that, and I’ll leanr something new too :p
-
-
Gemma Sharp answered on 16 Jun 2011:
Judith has given a good answer for fish, so I’ll explain the insects!
Well because there are so many types of insect, there are quite a few different ways that they lay eggs.
Usually, the male will fertilize the eggs inside the female by injecting his sperm inside, then the next part depends on the species. In some species the offspring will develop inside the eggs inside the female and hatch inside as well, so they’re ‘born’ alive. In other species the offspring will develop inside the eggs inside the female and she will lay them when they’re just about to hatch. And in other species the female will lay the eggs as soon as they’ve been fertilised and the offspring will develop in the egg outside the female’s body. The offspring hatch at larvae and later change (or metamorphose) into the adult form.
As a side point, something I learnt the other day, did you know Drosophila (a tiny fruit fly) has the longest sperm of any known organism on Earth? Apparently you can see it with the naked eye!
Comments