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
Whale conservation certain other species of high intelligence: humans, other great apes, bottlenose dolphins and elephants. There is an argument that whales should not be killed because of their high intelligence. Pro-whalers claim that pigs also possess high intelligence, and are routinely butchered and eaten, and that intelligence should not be the determining factor of whether an animal is acceptable to eat or not. Whale meat products from certain species have been shown to contain pollutants such as PCBs, mercury, and dioxins. Levels of pollutants in toothed-whale products are significantly higher than those of baleen whales, reflecting the fact that toothed whales