Phaeophyta (Brown algae)
  
A common feauture of the division Phaeophyta, distinguishing it from the other algae, is the presence in pigment composition of the fucoxantine which causes brown colour of these algae. Filiform, cord-like, lamiated and other forms are represented. Brown algae are the marine benthic organisms inhabitimg the seas of all geographic zones. In boreal and Arctic seas they prevail in the number of species, play the leading role in the flora, and predominate in the benthic communities.

The Laminariales and Fucales from vast thickets and determine the character of littoral and sublittoral vegetation. The thickets serve as environment and nourishment for many invertebrates and fishes. An overwhelming majority of brown algae are the lithophytes associated with solid grounds. Small filiform and crust forms often grow attached to other algae and animals.