Yes most of them do. That is one of the main reasons why dogs get spayed/neutered. In order to give birth, You need to of had your period first. So the animals that can give birth have a period. I don't know how long it is though. I am also not sure about fish, just mammals.
Um, what are you asking that my view is on? I could give you my view but I'm not sure what you are asking.
<span>Error bars within treatments illustrate confidence intervals, standard errors, standard deviations or other quantities. However, different types of error bars exist, so figure legends must be sure to distinguish which error bar is being represented. </span>