Polychaeta
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Polychaeta (polychaetes, bristle worms) class of the phylum Annelida or segmented, metameric worms. The cylindrical body segments normally have a
pair of fleshy appendages called parapodia that possess bundles of chetae.
Often a well developed head with several appendages is present. The mouth
can be furnished with a proboscis with jaws andlor teeth. The polychaetes are
a vast class (more than 7000 species), which by majority are marine. They
can be free-moving (errant) or sedentary and living in tubes. Most are burrowers and belong to the macrobenthos, a few are pelagic. Polychaetes show a
variety of feeding types. E.g. some tube-living animals have a crown of fine
tentacles for filter feeding (~filter feeders), the burrowers can be deposit feeders,
and again others can be fearsome predators.
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Polychaeta. (From Barnes 1987 after Brown 1950)
polychlors the term polychlors includes organochlor compounds, among which
those of DDT (and metabolites such as DDD, DDMU, and DDE), dieldrin,
endrin, aldrin (y-HCH). PCBs (polychlorobiphenyls) are the most common
as contaminants in the sea. Since the ban on DDT, dieldrin and endrin as pes-