Keeping the balls cool

[ttyo888]

Based on prior knowledge that testicle temperatures have to be cooler for optimal production and lifespan of sperm, I heard that marine mammals do not have a scrotum and keep their balls in their bodies. How do they keep their balls cool? Can the same mechanisms work on land if such a mechanism evolved too later on?

 

One sex joke made by a my friend who studies bio-chem was that if men kept their balls to themselves, there would be less incidents like the below.

http://www.whatsonsanya.com/news-17236-outrage-sparked-after-monkey-bites-off-boy-s-testicle-at-zoo-in-guizhou.html