Explanation:
Well, its extremely hot in the hydrothermal vents. Scientists simply believed it would be impossible for anything to survive due to the heat. Bacteria and micro-organisms were able to adapt to growing there, though. So in short words, they survived extreme conditions teaching scientists that life was quite adaptable.
Weird fun fact: In Switzerland it is illegal to own just one guinea pig. Felt the need to mention that ^ Sorry, I know it has nothing to do with the question but i felt it was worth speaking of.
B. Funnies cell wall are mostly made of chitin not cellulose.
You can use the volume displacement method. If you had the alligator in a tank and you knew how much the volume of water in the tank was before the alligator was in there you could subtract that from the volume of the water with the alligator in the tank.
Using things such as the internet. For example, if a scientist wanted feedback, he could turn to an org of other scientists across the globe and get their help.