These beauties are known as deep-sea octorals, or soft corals. Otherwise commonly referred to as mushroom coral (Anthomastus ritte), these cnidarians use stinging cells or nematocysts within their stunningly flashy tentacles in order to catch prey. Deep sea mushroom coral has been found at depths where natural light cannot reach, so photosynthesis could not occur. Since most corals are dependent on this transformation of light into sugar, becoming predators has allowed them to flourish where other reefs would wither away. Rather than turning the sunlight into a form of energy they can digest, they instead just eat prey that swims by and turn that into energy.

Photo credit: NOAA, Ocean Explorer

Gorgonian coral (Order Alcyonacea, previously Gorgonacea)

Aronnax identifies “some gorgonian coral arranged like a fan” (20,000 Leagues p. 74) among Nemo’s specimens. He is presumably referring to some type of sea fan, soft coral in the order Alcyonacea (also known as sea whips). Alcyonacea found in shallower water, with stronger currents, are more flexible and look more like fans; the photograph shows a Venus fan (Gorgonia flabellum).