page_title: Baleen whale
section_title: Differences between families
hierarchical_section_title: Baleen whale / Taxonomy / Differences between families
caption_attribution_description: English: Size comparison of living baleen whale species.
context_page_description: Baleen whales, also known as whalebone whales, form a parvorder of the infraorder Cetacea. They are a widely distributed and diverse parvorder of carnivorous marine mammals. Mysticeti comprise the families Balaenidae, Balaenopteridae, Cetotheriidae, and Eschrichtiidae. There are currently 15 species of baleen whales. While cetaceans were historically thought to have descended from mesonychids, molecular evidence supports them as a clade of even-toed ungulates. Baleen whales split from toothed whales around 34 million years ago.
  Baleen whales range in size from the 6 m and 3,000 kg pygmy right whale to the 31 m and 190 t blue whale, the largest known animal to have ever existed. They are sexually dimorphic. Baleen whales can have streamlined or large bodies, depending on the feeding behavior, and two limbs that are modified into flippers. The fin whale is the fastest baleen whale, recorded swimming at 10 m/s. Baleen whales use their baleen plates to filter out food from the water by either lunge-feeding or skim-feeding. Baleen whales have fused neck vertebrae, and are unable to turn their head at all. Baleen whales have two blowholes.
context_section_description: Rorquals use throat pleats to expand their mouths, which allow them to feed more effectively. However, rorquals need to build up water pressure in order to expand their mouths, leading to a lunge-feeding behavior. Lunge-feeding is where a whale rams a bait ball (a swarm of small fish) at high speed. Rorquals generally have streamlined physiques to reduce drag in the water while doing this.
  Balaenids rely on their huge heads, as opposed to the rorquals' throat pleats, to feed effectively. This feeding behavior allows them to grow very big and bulky, without the necessity for a streamlined body. They have callosities, unlike other whales, with the exception of the bowhead whale. Rorquals have a higher proportion of muscle tissue and tend to be negatively buoyant, whereas right whales have a higher proportion of blubber and are positively buoyant. Gray whales are easily distinguished from other extant cetaceans by their sleet-gray color, dorsal ridges (knuckles on the back), and their gray-white scars left from parasites. As with the rorquals, their throat pleats increase the capacity of their throats, allowing them to filter larger volumes of water at once. Gray whales are bottom-feeders, meaning they sift through sand to get their food. They usually turn on their sides, scoop up sediment into their mouths and filter out benthic creatures like amphipods, which leave noticeable marks on their heads.
  The pygmy right whale is easily confused with minke whales because of their similar characteristics, such as their small size, dark gray tops, light gray bottoms, and light eye-patches.
caption: Baleen whales vary considerably in size and shape, depending on their feeding behavior.
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