We went past this group of fishermen on a boat who waved at us as we passed by. The Backwaters is big business for fishermen and you'll get to see a lot of them and fishing boats as part of your tour.
Coracles are flat basketlike craft used to ferry people & sheep (yes sheep!) and are about 6 feet in diameter. They are made of bamboo, cane, plastic sheets and a fine coating of bitumen to make it leak proof. They're used, here, for fishing as well as to get from one side of the river to the other. I had seen them being used in Hampi so it was nice to see them on the Backwaters as well as more conventional means of water transportation.