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zoogonidia, or swarm spores, special cells in many algae and some lower fungi that are capable of moving in water like protozoans by means of flagella, whose number varies in different species (usually two, more rarely one, four, or more).
Zoospores function in asexual reproduction and settlement. In contrast to typical plant cells, zoospores do not have a rigid membrane. The zoospores of many algae have, in addition to a chromatophore, red ocelli and pulsating vacuoles. The movement of zoospores is forward and rotary; after some time a zoospore stops, loses its flagella, secretes a rigid membrane, and develops into a new alga or fungus organism. The cells in which zoospores are formed are called zoosporangia.