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
Gills Bay Gills Bay Gills Bay, which is situated about west of John o' Groats with the community of Gills close by, has one of the longest stretches of low-lying rock coast on the northern shores of Caithness. Its main features are a small harbour and the pier used as the mainland terminal for Pentland Ferries. The harbour shelters some small local boats together with those used for working the sheep on the off lying island of Stroma. In the right sea conditions the area is sometimes used for surfing. While Scrabster to Stromness is the longest continuously used ferry route to