Thanks for the lesson!Too bad Dolphins are mammals and are known to be natural enemies of sharks.
As I understand it, the Dolphin's attack and kill sharks by being able to swim faster than most of them and being able to turn in the water faster than any of them.
Dolphins can control their skin texture and make one side of their body "rougher" than the other. This increases friction with the water and allows for faster, tighter turns. Sort of like regular tires vs "racing slicks".
The sharks have a rough skin (it used to be used for making "Emory" boards (used in nail polishing and shaping). This is a "fine" level of texture and allows for greater speed by reducing the surface area of their skin hitting the water the faster they go. New Zealand won a world record with ocean racing sail boats by applying what shark skin does; by adding "dimples" to the underwater surface of their boats This was about 30 years ago.
The dolphins kill the sharks by ramming headfirst into the side of the shark, using their pointy head as a battering ram. It turns out that sharks do not qualify as true "boney" fish because most of their body's framework, with the exception of the skull & spine, are cartilage. This turns out to be a weak spot that the Dolphins take advantage of.
Yes, I use to read the encyclopedia just for fun. I even know what an Aardvark and an Aardwolf are (hint: they are two very different animals) - LOL
Now off to research an aardwolf