Question

Why do you think that frogs only produce hundreds of eggs at a time whereas sea urchins must produce millions if they are to reproduce effectively?

Answer 1

Because they produce in water that's why we didn't know about it

Answer 2

Frogs are much more active and efficient parents than sea urchins are. Frogs are able to protect and care for eggs until they hatch, whereas sea urchins cannot. Therefore, sea urchins need to produce more eggs to account for higher mortality.