In the study, the researchers demonstrate how the comb jellies
evolved, describing the organic skeleton it had during the Cambrian period - earliest time division of the Paleozoic Era, extending from 541 million to 485.4 million years ago.
The extinct oddball comb jellies
with skeletons fit with the idea that early life-forms may have been unusually diverse, Moroz says.
They also decoded gene activity of nine additional species of ctenophores -- the scientific name for comb jellies. (The ''c'' is silent.)
First, they found comb jellies represent the oldest branch of the animal family tree -- not the simpler sea sponges traditionally thought to hold that spot, the team reported.
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.
Comb jellies and the single-celled organisms turn out to lack many genes that animals typically have.
Vertical rows, or combs, made of hundreds of iridescent, hairlike cilia run the lengths of their globular bodies (thus the name comb jellies
living in the central Baltic Sea are a bunch of babies.
This specimen from the Arctic is probably a new species of comb jelly, (Unlike true jellyfish, in the phylum Cnidaria, comb jellies
don't have stinging cells.) Census participants have lamented the current shortage of experts able to classify the vast numbers of organisms that have been pulled from the seas in the past decade.
Some scientists have suggested that comb jellies
, not sponges, were the first multicellular animals (SN: 4/5/08, p.
Now a team of biologists suggests demoting sponges and placing comb jellies
at the base of a new tree of animal life.
For example, one cruise in the Arctic doubled the known diversity of comb jellies
there, from 5 species to 10.
On the other hand, Breitberg has found that the Bay's gelatinous species--its comb jellies
(Mnemiopsis leidyi) and stinging sea nettles (Chrysaora quinquecirrha)--are quite tolerant of hypoxia.
First identified in 1982, populations of these comb jellies
(Mnemiopsis leidyi) soon swelled to dramatic proportions, contributing to the 1989 crash of the Black Sea's largest surviving fishery: anchovies.