Free-floating globose colony formed by numerous filaments radiating from a common center. Colonies can easily be seen with the unaided eye as floating "fuzz-balls" about 2 mm (or 1/16") in diameter. Each filament tapers from a basal heterocyst into a fine hair- like tip extending beyond the mucilage which holds the colony together. Vegetative cells near the base of each filament are spherical to barrel-shaped (8-10 mm diameter), becoming long and noticeably tapered at the opposite end. Highly refractive pseudovacuoles are present which allow colonies to be buoyant. The single, basal heterocyst is spherical (10 mm diameter). Akinete is adjacent to heterocyst and cylindrical (10-18 mm diameter; up to 50 mm long).
At least one chemically undefined hepatotoxin is under investigation. In addition, cell wall lipopolysaccharides have been implicated as cytotoxins, a group of toxins that are not highly lethal to animals but could account for skin irritations and outbreaks of gastroenteritis in swimmers.
Hepatotoxin toxicosis may exhibit jaundice, abdominal pain/distention, weakness, and nausea/vomiting. No animal deaths have been directly associated with this organism. Cytotoxin toxicosis may appear as skin irritation or gastrointestinal upset by humans swimming in water experiencing a bloom.
This information is from "Toxic Cyanobacterial Blooms - A Field/Laboratory Guide". This guide was written by Dr. M. A. Crayton from Pacific Lutheran University, Tacoma, Washington and edited by Dr. F. Joan Hardy, Washington State Department of Health. Used with permission.
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