Seaweed
"Seaweed" is a colloquial term and lacks a formal definition. A seaweed may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae. As these three groups do not have a common multicellular ancestor, the seaweed are in a polyphyletic group. In addition, some tuft-forming bluegreen algae (Cyanobacteria) are sometimes considered to be seaweed.
Seaweed blenny
The seaweed blenny is native to shallow waters in the western Atlantic Ocean. Its range extends from New York southwards to Brazil, and includes the Caribbean Sea, the Gulf of Mexico, Bermuda and the Bahamas at depths down to about . A typical habitat is among limestone boulders and in scoops and basins where the rock surface is covered with a mat of algae, sea fans and other invertebrates. It is also found on reefs, in seagrass meadows and oyster beds, as well as around man-made structures such as pilings, jetties, seawalls, oil rigs and buoys, and among the roots of mangroves.