animal Type
Maximum Size

16 cm

(6 inches)


250–1,500 m

(820–4,900 feet)



in the twilight (mesopelagic) zone, including the oxygen minimum zone




North Pacific Ocean

Canada to Baja California, Japan


The blood-red stomach disguises the glowing prey inside.

Many of the deep-sea animals the bloody-belly comb jelly preys upon can bioluminesce, or create their own light. The translucent predator needs to conceal its stomach—or risk its most recent meal lighting it up from the inside out and alerting potential predators to its whereabouts. Red is nearly invisible in the deep sea, so the vibrant crimson that gives this comb jelly its name is actually helping it hide from its predators.

Bloody-belly comb jellies are ctenophores, not true jellies. Like other comb jellies, they navigate through the water by beating their shimmering, hair-like cilia.


Video Clips


Christianson, L.M., S.B. Johnson, D.T. Schultz, and S.H.D. Haddock. 2021. Hidden diversity of Ctenophora revealed by new mitochondrial COI primers and sequences. Molecular Ecology Resources, 22: 283–294.

Harbison, G.R., G.I. Matsumoto, and B.H. Robison. 2001. Lampocteis cruentiventer gen. nov., sp. nov.: A new mesopelagic lobate ctenophore, representing the type of a new family (Class Tentaculata, Order Lobata, Family Lampoctenidae, fam. nov.). Bulletin of Marine Science, 68: 299–311.

Puente-Tapia, F.A., R. Gasca, A. Schiariti, and S.H.D. Haddock. 2021. An updated checklist of ctenophores (Ctenophora: Nuda and Tentaculata) of Mexican seas. Regional Studies in Marine Science, 41: 1–20.