So I was watching Jaws 3D just now, and this question just popped into my head.

I would think most of us actually take the myth/fact that "Sharks are driven crazy by the smell of blood"for granted, but the movie just got me thinking if this was really true, so asked my friend Google:


1) It is true that sharks can indeed detect tiny amounts of blood from quite a distance away. For instance, Great White sharks can actually detect one drop of blood in 100L of water, and can even sense tiny amounts of blood up to 5km away.

2) However, blood is not the only thing that attracts these hugely misunderstood creatures. Any kind of body fluid actually has relatively the same effect on them. Moreover, based on a study done by H. David Balridge, the only body fluid that elicited a feeding frenzy was peritoneal fluid.

3) Even menstrual blood was tested in the above mentioned study. It did not elicit any notable reactions. Feedback from many menstruating female divers also claimed that that particular time of the month has no effect on sharks when they go diving. One such individual was Marie Levine, founder and executive director of the Shark Research Institute, who lamented that even when she was among a school of Hammerheads during her period, the sharks were not interested in her, and she had to "fin like crazy to get close to them".

4) Interestingly, based on the above study by Collier; rather than human blood, blood from animals native to the marine environment are what really riles uo the sharks to a feeding frenzy.Human blood on the other hand, is from a terrestrial environment. He theorizes that the scent of human blood doesn't send the message to sharks that there is an animal in distress nearby, fit for a meal.



And there you go. That ends today's random fact(s) about this misunderstood creature of the sea.

Have a great day! <3

P.S. Many people still caution against diving during that time the month for a woman.



References:
RelevanSea ~ A Marine Conservation Blog - Are sharks really attracted to human blood?
Do Menstruating Women Attract Sharks? | Mother Jones