Something I never thought about... I guess jelly fish do range into the colder waters. I grew up swimming in the Chesapeake Bay as a kid and learned to avoid the larger stinging ones. The little ones were fun to swim through!
thanks for bringing back great memories and teaching me something new.

http://www.mdsg.umd.edu/topics/jellyfish/jellyfish

According to this study what we liked to swim through were the moon jelly.