Phylum: Ctenophora
This is a nice picture of a ctenophore from Monterey Bay Aquarium. Ctenophores are often confused with jellies, as they look similar, and have only two cell layers + the mesoglea. However, ctenophores lack the special stinging cells which characterizes all members of the cnidarians (jellies, anemones, and the like). They do have special sticky cells called colloblasts, which they use for feeding. They are active predators, and can use either sticky tentacles or muscular lobes to capture their prey. the above ctenophore is a lobed variety, and catches its prey by closing those large lobes around it. You can see some of the copepods that it had for lunch in its gut.
The other way comb jellies are different from your average jelly is: the way in which this animal moves. The creature cast produced an excellent movie describing this unique (for a multi-cellular organism) mode of locomotion. If you watch, you should also be able to explain why the comb jelly in my picture has beautiful rainbow stripes...
CreatureCast - Comb Jelly Movement from Casey Dunn on Vimeo.
