A humpback whale will eat up to two tons of krill a day. Humpbacks are known as baleen whales. That means they have fibrous plates of baleen which hang like curtains from their upper jaw instead of teeth. There are as many as 300 to 400 baleen plates on either side of their mouth, which act as a filter separating the krill from the sea water. Baleen, which is made of keratin just like our fingernails, is an extremely efficient sieving device for catching the tons of krill that the Humpback eats.
Humpbacks use at least two methods of feeding.
If the krill are centered near the surface of the water the humpback whale then uses a method called lunge feeding. Now bubble-net feeding is another method used by the Humpbacks in their quest for food. This technique is to dive beneath a swarm of krill and blow a series of bubbles which has the effect of concentrating the krill. The Humpbacks will then spiral up to the center of the bubbles, with mouths and upper belly fully extended, catching everything in their wake. Humpback whales have skin groves on the lower jaw and upper breast plates which allows them to expand their upper body which, when full of krill, looks like a huge balloon.