The answer is a simple radial nervous system.
Echinoderms do not have brains. Around their mouth, they have central rings from which nerves radially run into arms and along the body. Movement is controlled by the branches of those radial nerves.
Warm blooded animals living on land
The fact that they can breed but cannot produce fertile offspring shows that they are different species. T<span>hey may have different characteristics which means they cannot breed </span>successfully, too.
I hope this helps! :-)
xo Leafling
I think homologous structures is a great example and idea that supports the theory of evolution. Homologous structures shows us how our futures evolved by natural selection.
I believe it’s gamete. Genotypes are traits that are genetic inherited. Phenotypes are traits you learn. Zygotes are a fertilized female egg.