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 568 ml, in countries serving large numbers of American tourists it might be a US liquid pint of 473 ml, in many metric counties it is a half-litre of 500 ml, or in some places it is another measure reflecting national and local laws and customs. Historically, units called a pint (or the equivalent in the local language) were used across much of Europe, with values varying between countries from less than half a litre to over one litre. Within continental Europe, these pints were replaced with liquid measures based on the metric system during the 19th century. The term