Kingdom
Protista
The Kingdom Protista or Protoctista is a diverse group of largely single celled eukaryotes. While many Protists are small and invisable to the unaided eye, a few are quite large. For example the Phylum Phaeophyta, or brown algae, is a group of multicellular Protists including the giant Kelp, which can reach up to 100meters(300feet) long and form the famous kelp "forests" of the Pacific.
Ecologically the Protista are highly diverse, some being heterotrophs while others are important autotrophs. Protists are a very important component of many ecosystems. Some protists are important parasites such as Trypanosoma which cause sleeping sickness and the Plasmodium which cause Malaria. In addition, many species of termites depend on certain flagellated Protists to digest cellulose.
Protists are extremely important in ecological and medical research. For instance
much understanding of interspecific competition come from protists. In medicine,
certain protists are used to study the relationship between chromosomal structure
and aging. Muticellular protists such as slime molds provide valuable insight
about the chemical signals used in more complex organisms to coordinate cellular
activity.
pgd revised 2/17/01