Photographs of diatoms taken through a microscope. 

 Coscmodisais(\eft} and the chain of Chaetocems 

 (right) are centric diatoms. Pseudonittschia (bottoml 

 produces domoic acid, which can contaminate shell- 

 fish and cause "amnesic shellfish poisoning" in 

 humans who eat the shellfish. Symptoms include 

 abdominal cramps, vomiting, disorientation, memory 

 loss, and even death. Scale bars are in micrometers 

 (urn); 1 micrometer is one-millionth of a meter or 

 about 1/25,000 of an inch. 



34 Biology and Ecological Niches in the Gulf of the Farallones 



