Filter feeder gap between the two rows of baleen plates lets the water in together with the prey, while the baleens filter out the water. Rorquals such as the blue whale, in contrast, have smaller heads, are fast swimmers with short and broad baleen plates. To catch prey, they widely open their lower jaw — almost 90° — swim through a swarm gulping, while lowering their tongue so that the head's ventral grooves expand and vastly increase the amount of water taken in. Baleen whales typically eat krill in polar or subpolar waters during summers, but can also take schooling fish, especially
Baleen whale D. W. Rice (of the Society for Marine Mammalogy) in assumed was an ironic reference to the animals' great size. An alternate name for the parvorder is "Mystacoceti" (from Greek "mustache" + "whale"), which, although obviously more appropriate and occasionally used in the past, has been superseded by "Mysticeti" (junior synonym). Mysticetes are also known as baleen whales because of the presence of baleen. These animals rely on their baleen plates to sieve plankton and other small organisms from the water. The term "baleen" (Middle English "baleyn, ballayne, ballien, bellane", etc.) is an archaic word for "whale", derived from the