Article Summary #2
Scientists have unearthed a new species of single-celled animals
called Pfiesteria piscicida. These perpetrators are the culprits
for the many deaths among a billion fish in the eastern U.S. waters.
The fish are left with bloody sores after the large groups of animals attack
them. One of the discoverers was JoAnn Burkholder of North Carolina
State University. She helped them name the species, which means "Fish
Buckholder thinks that Pfiesteria originally fed on bacteria and algae, but then later turned to larger prey for a good reason. The recent farm and development around the area caused an abundance of nutrients to be poured into the rivers. This made a shift in their feeding habits enabling them o attack in a group for fish. Humans who have been exposed to this organism have developed the same type sores, severe memory loss, and other cognitive problems.
It has been found that Pfiesteria is so dominant because of its complex life cycles. It has 24 known forms. It begins as a dormant cyst living on the bottom of the river until the waste of a dead fish triggers if to change to a toxic form. Then they propel themselves with their whip-like tails to poison the fish with their venom. As the fish die, Pfiesteria reproduce and feed on the fish's fluids. Fresh cysts then fall to the bottom to await new victims. The amoeba-like forms have a shell that armors it against microbial predators. When in this form, they scavenge on dead fish later changing to prey on bacteria and algae. At other times, Pfiesteria extracts the chloroplasts from algae and uses the photosynthesis to supplement their food supply. Thus, this masquerades this animal as a plant.
From Discover, The Jaws You Can't See by Catherine Dodd, January 1998,