QUESTION:
How do parameciae behave in space? I know that from current study, the
microprotists simply propell themselves with their cilia and change thier
direction when they run into an object. But, may these systems be
complicated in the zero gravity of outer space?

ANSWER from Guy Etheridge on June 6, 1997:
The question you're posing is very relevant to experiments which many NASA
scientists have been proposing in recent years. For instance, in the ARF-01
(Aquatic Research Facility; May, 1996) experiment, investigators from the
Univ. of British Columbia studied motility patterns in starfish larvae
cultured under conditions of microgravity, and others looked at shellfish
larval motility patterns. A variety of investigations over the years have
looked at fish motility patterns.  The general result is that patterns of
movement do indeed change in space because many of these critters have
built-in gravity receptors which provide them with an up-down orientation.
For example, some newly hatched fish larvae will swim in loop patterns in
space. A quick review of our literature has not turned up any comparable
studies on Paramecium species, but they would certainly be worthy subjects
for study.  Often the number of cilia formed in these small invertebrates
gets reduced in space. Certainly this could change their pattern of motility
if nothing else does.