I've changed the previous version which stated that the bull shark has the highest testosterone levels of all animals to read that it has one of the highest, this because I am sitting with a brief guide to elephant seals I got while visiting Año Nuevo State Reserve. It claims that Elephant Seals have the highest levels of testosterone of any animal and this is one of the reasons they were nearly hunted to extinction. Anyone with a field speciality in Sharks and Elephant Seals care to weight in?    

 :I'm removing this claim from the article.  The current reference does not contain the word "testosterone" (as of 3 Apr 2007). Most google hits for bull shark testosterone seem to be taken straight from wikipedia, although this full transcript contains the quote: "I guess it has the highest testosterone level of any animal."  My guess is that this speculation might have turned into a "fact", Chinese whispers style.  In any case, the claim is meaningless unless we know how many animals have actually had their testosterone levels measured.    

 ::Hawaiian grad student Christie Wilcox shared my skepticism about bull sharks and testosterone and wrote a blog entry about it.  Her conclusion: "...the idea that bull sharks are super juiced-up compared to other animals just isn't true."  Of the two sources the Wikipedia article previously cited to support the claim, one says nothing about aggression, and the other doesn't mention testosterone at all.  •contribs)  

 ::: She has just updated her post with new data, in which she further dispels this myth:   
 ::: No, thanks.  —'''''' ''''''