The extinct oddball comb jellies
with skeletons fit with the idea that early life-forms may have been unusually diverse, Moroz says.
In a test run off the coast of Florida this spring, The Associated Press documented how his team is studying which genes switch on and off as iridescent comb jellies regenerate from injury.
They also decoded gene activity of nine additional species of ctenophores -- the scientific name for comb jellies.
Comb jellies possess muscle cells, but the analysis of the Mnemiopsis genome showed that comb jellies lack the vast majority of genes that specify muscle types in most other animals.
According to the researchers, the absence of such a large number of muscle genes suggests that muscle cells evolved independently in comb jellies, after they diverged from the rest of the animals.
There were about 400 comb jellies per cubic meter (that's like 200 golf ball--sized jellies in a space as big as a bathtub).
For example, the animals known as comb jellies look in many ways like true jellyfish, but are actually distant cousins.
Ryan and his colleagues questioned this scenario at a meeting in January when they announced that comb jellies
may descend from an ancestor that evolved before sponges.
are gelatinous like jellyfish, but the similarity ends there.
Jaspers and her colleagues suspect that pressure from predators might be driving these comb jellies
to start producing a few eggs early in life.
By 1991, Mee notes, "There were about 1 billion tons, wet weight, of comb jellies
in the Black Sea.
The most likely candidates for biocontrol include Baroe, another ctenophore that eats only comb jellies
, and the butterfish, a fish of low commercial appeal with a fairly catholic diet that includes Mnemiopsis.