UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
Why do some animals have actual babies and some have eggs?
Question Date: 2009-05-15
Answer 1:

The ability for some animals to have live births versus eggs can normally be explained by what classification the animal belongs to. Mammals have live births, birds have eggs, Echidn as (a relative of mammals, think platypus)have eggs (like birds) but also have some characteristics only seen in mammals (fur and milk for their young). There are some classification of animals that can have either live birth or eggs, such as sharks, fish and some reptiles. The difference between the whether there are live births versus eggs is usually determined by the environment.



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2017 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use