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 Rock, Wisconsin Gills Rock, Wisconsin Gills Rock is an unincorporated community located on Highway 42 at the northern tip of the Door Peninsula in Door County, Wisconsin, United States. It is within the town of Liberty Grove and was formerly known as Hedgehog Harbor. The area was named for Elias Gill, a local 19th century landowner. Gills Rock has a strong history and tradition of commercial fishing, which continues to this day. The Door County Maritime Museum is located there. The area is also popular with scuba divers who explore the many shipwrecks in and around "Death's Door", the narrow strait connecting