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 smaller than the US fluid ounce. All of the other former British colonies, such as Canada, Australia, South Africa and New Zealand, converted to the metric system in the 1960s and 1970s; so, while the term "pint" may still be in common use in these countries, it may no longer refer to the British imperial pint once used throughout the British Empire. In the United Kingdom, the imperial pint is still the primary unit for draught beer and cider, as it is for milk sold in returnable bottles and some cartons. In the UK, legislation mandates that draught beer and