m Before it said that only Balaenids have callosities with the exception of the bowhead whale. The bowhead whale is a balaenid. I changed to so that it would say "Balaenids have callosities, which is uncommon in other whales"
[[File:Baleen whale sizes.JPG|thumb|Baleen whales vary considerably in size and shape, depending on their feeding behavior.]]
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 [[bait fish|small fish]]) at high speed. Rorquals generally have streamlined physiques to reduce drag in the water while doing this.<ref>{{cite journal|first1=J.|last1=Potvin|first2=J. A.| last2= Goldbogen|first3=R. E.|last3=Shadwick|year=2009|title=Passive versus active engulfment: verdict from trajectory simulations of lunge-feeding fin whales ''Balaenoptera physalus''|journal=Journal of the Royal Society Interface|volume=6| issue=40|pages=1005–1025|doi=10.1098/rsif.2008.0492|pmid=19158011|pmc=2827442}}{{open access}}</ref>
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]], unlikewhich otheris whales,uncommon within theother exception of the bowhead whalewhales.{{sfn|Bannister|2008|loc=[https://books.google.com/books?id=2rkHQpToi9sC&pg=PA80 p. 80]}} 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.<ref>{{cite journal|first=C.|last=Lockyer|year=1976|title=Body weights of some species of large whales| journal=Journal du Conseil International pour l'Exploration de la Mer |volume=36|issue=3|pages=259–273|doi=10.1093/icesjms/36.3.259}}</ref> Gray whales are easily distinguished from the other rorquals by their sleet-gray color, dorsal ridges (knuckles on the back), and their gray-white scars left from parasites. As with the other 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 [[amphipod]]s, which leave noticeable marks on their heads.<ref>{{cite book|chapter-url={{Google books|plainurl=yes|id=GfGITi5NmJoC|page=423}}|editor-first1=Mary Lou|editor-last1=Jones|editor-first2=Steven|editor-last2=L. Swartz|editor-first3=Stephen|editor-last3=Leatherwood|year=1984|title=The Gray Whale: Eschrichtius robustus|chapter=A Review of Gray Whale Feeding Ecology|pages=33–34, 423–424|isbn=978-0-12-389180-8|last1=Jones|first1=Mary Lou|last2=Swartz|first2=Steven L.|last3=Leatherwood|first3=Stephen|publisher=Elsevier Science }}{{open access}}</ref> 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.{{sfn|Bannister|2008|loc=[https://books.google.com/books?id=2rkHQpToi9sC&pg=PA80 p. 80]}}
