“Ctenophores have been described as the most beautiful, delicate, seemingly innocent yet most voracious, sinister and destructive of plankton organisms.” (Mianzan et al., 2009)

Ctenophores are gelatinous marine animals, similar in many ways to jellyfish but lack stinging cnidae, and movement is via the coordinated beating of cilia (“combs”) instead of muscular contractions. As of 2008, about 150 species had been described. They occur throughout the ocean, at all depths and are mostly planktonic, though a few are benthic. Comb jellies are efficient predators, consuming zooplankton such as fish eggs, copepods, amphipods, and larvae. Some eat jellyfish, salps, and other ctenophores. They range in size from a few millimeters to 2 m long, and most are transparent and bioluminescent.

(Ruppert et al., 2004; Mianzan et al., 2009)

Ctenophores occur in all oceans and all depths. Most species are planktonic, so live within the water column, but the platyctenids are benthic and attach to the surfaces of sessile organisms. (Unlike most ctenophores, which are transparent, the platyctenids are pigmented in camouflaging patterns.)

(Ruppert et al., 2004)

All ctenophores are carnivores (Mianzan et al., 2009).

Ctenophora (Ctenophores) is prey of:
Peprilus triacanthus
invertebrate predators
Ctenophora
Chaetognatha
Actinopterygii
Clupea harengus
Alosa pseudoharengus
Scomber
Pollachius pollachius
Merluccius bilinearis
Urophycis regia
Urophycis tenuis
Urophycis chuss
Gadidae
Melanogrammus aeglefinus
Leucoraja erinacea
Leucoraja ocellata
Amblyraja radiata
Paralichthys dentatus
Pleuronectes americanus
Mustelus canis
Squalus acanthias
Odontoceti
Scombridae
Other suspension feeders
Mya arenaria
Crassostrea virginica
Polychaeta
Nereis
meiofauna
Callinectes sapidus
Alosa chrysochloris
Anchoa mitchilli
Brevoortia tyrannus
Alosa sapidissima
Micropogonius undulatus
Trinectes maculatus
Morone americana
Arius felis
Pomatomus saltatrix

Based on studies in:
USA: Rhode Island (Coastal)
USA, Northeastern US contintental shelf (Coastal)
unknown (Marine, Pelagic)
USA: Maryland, Chesapeake Bay (Estuarine)

This list may not be complete but is based on published studies.

Ctenophora (Ctenophores) preys on:
Acartia
Acartia tonsa
detritus
bacteria
Copepoda
Calanus
Oithona-Oncaea type
Euchaeta
Centropages
Amphipoda
Euphausia
ciliates and nauplii
Pseudocalanus
invertebrate predators
Ctenophora
Chaetognatha
phytoplankton
Pteropods
Bacteria attached to suspended POM
Bacillariophyceae

Based on studies in:
USA: Rhode Island (Coastal)
Pacific (Tropical)
USA: North Carolina, Pamlico (Estuarine)
USA, Northeastern US contintental shelf (Coastal)
unknown (Marine, Pelagic)
USA: Maryland, Chesapeake Bay (Estuarine)

This list may not be complete but is based on published studies.

Light used for instant signaling: comb jellies
 

An enzyme called photoprotein in comb jellies produces light when calcium changes the enzyme's shape, releasing energy.

   
  "In a firefly bioluminescence reaction, an enzyme known as a luciferase uses adenosine triphosphate (ATP) to activate a molecule called a luciferin. The product of this reaction combines with molecular oxygen to produce an excited-state oxyluciferin species. When oxyluciferin relaxes back to its ground state, energy is released in the form of light…Jellyfish-like animals called ctenophores—can do without [ATP to jump-start bioluminescence]. Instead, they use a luciferin of intrinsically higher energy and prepackage it with oxygen in an enzyme known as a photoprotein. Calcium activates the reaction by changing the shape of the photoprotein, which releases the invested energy in the form of light." (Pepling 2006)
  Learn more about this functional adaptation.