External gills usually contains muscle tissue, and may be moved by the animal as a free appendage, in order to stir up stagnant water. The stalk is lined by many thinly walled filaments (fimbriae), containing the majority of blood vessels used in gas exchange. Animals usually have one external gill originating on each gill arch (except the hyoid), which leads to there being three pairs of external gills in salamanders, and four in the gilled larvae of lungfish. External gills External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside
Pint ml (20 fluid ounces). With the allowed margin of error of 0.5 fluid ounces, a "pint" that is less than 554 ml of beer is an offence, though—to the detriment of consumers—this regulation is often violated and rarely enforced. After metrication in Canada, companies sold milk and other liquids in metric units so conversion issues could no longer arise. Legally speaking, although some British imperial units are still legally usable in Canada, as a result of Canada's colonial history, the "pint" served in drinking establishments in Canada should be the larger 20 ounce British imperial pint, rather than the smaller