> Date: Sun, 08 Mar 1998 19:53:09 -0500 (EST) > From: User343965 <User343965@aol.com> > To: aRomero@ACC.FAU.EDU, email@example.com > Subject: Blue whales > > My name is Billy and I am a fifth grade student at Wilson Middle School in > Natick, MA. Could you please answer the following questions for me? > > 1.Why are female blue whales larger than males? > 2.How wide is the blow hole on blue whales and are female and male the same > size? > 3. What is the life expectancy of the average blue whale? > I am working on a project with my class and any help you can give me is > appreciated. > Thank you. Dear Billy: It is no entirely clear why females are larger than males. I would speculate that it is because being viviparous animals like any other mammals (except for the platypus and its allies) carrying a fetus may require more space. In other species it is the male the one larger but that is due to the fact of certain dominance of male over females in the social structure of the group. This and other differences between males and females is what is called "sexual dimorphism." I have not been able to find specific figures on the size of the (two) blowholes of the blue whale, but remember that these structures are extremely flexible having to open and close constantly. There is a great deal of disagreement regarding maximum age estimates which range from 30 to 90 years. Given that this species has been decimated, those calculations have become very imprecise due the relatively low number of individuals left. Best wishes, Aldemaro Romero, Ph.D.