Bloody-belly comb jelly

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.