Assertion: humpback whale's jaw | /r/MadeOf | keratin
Facets:
Source sentences:
text: These Whales have a sieve-like structure in the upper jaw made of keratin (the same substance rhino horns are made of) which they use to filter plankton from the water.
text: Cetaceans are divided into two parvorders: the largest parvorder, Mysticeti (baleen whales), is characterized by the presence of baleen, a sieve-like structure in the upper jaw made of keratin, which it uses to filter plankton, among others, from the water; Odontocetes (toothed whales) are characterized by bearing sharp teeth for hunting, as opposed to their counterparts' baleen.
text: They have a pair of blowholes side-by-side and lack teeth; instead they have baleen plates which form a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water.