Monotremes, like the platypus, lay eggs and don't have placentas. So how does the mother's body know when to start lactating?
Sure, there are physical differences but outside of mammals, the terms "male" and "female" take on different meanings.
Did you know that there are fish out there that can change sex?
You may think milkweed is just a stubborn weed, but to some it's a valuable commodity.
Chloroplasts should not be able to work once they are removed from algal cells because those cells contain proteins that control their operation.
The most common hypothesis why birds' eggs are speckled is that the speckles help camouflage the eggs, making them harder for predators to see.
Until very recently, humans tended to reproduce before reaching full adult maturity, as did the dinosaurs. Learn more on this Moment of Science.
If you've ever made a cream pie and it turned into a soupy disaster overnight, then you know about this common frustration.
As part of the mating process, female giant water bugs latch onto male water bugs and cement as many as one hundred and fifty eggs to his back, then leaves.
Brown-headed cowbirds are robin-sized black birds whose range covers most of North America. From a people’s point of view cowbirds are what we might call deadbeat parents. Cowbirds lay their eggs in the nests of other bird species, and the cowbird nestlings are raised by the foster parents. Since the cowbirds spend their formative months with birds of an entirely different species which has separate habits, songs, etc., how does a cowbird know it’s a cowbird? Learn more on this Moment of Science.