St. John Marine Life: Orange Cup Coral

orange cup coral
Orange Cup Coral (Tubastraea coccinea)
Cup Coral and Brain Coral
Brain Coral (top) and Cup Coral (bottom)

I just found out that one of my favorite hard corals, the Orange Cup Coral (Tubastraea coccinea), is considered an invasive species.

Orange cup corals are beautiful brightly colored orange corals with flower-like yellow tentacles that extend at night or in areas of low light.

Although the orange cup coral is a hard coral, it’s not a reef-building coral. Also, unlike other corals, the cup coral, does not depend on the symbiotic algae, which shares it’s photosynthesis-created food with the coral animal. Because of this, the cup coral can grow in dark places such as shaded walls, caves and underneath overhanging ledges.

I first noticed orange cup corals on the walls of an rocky indentation on the Tektite snorkel and again on the walls of the caves at Norman Island. Now I see them elsewhere even on the Trunk Bay Underwater Trail.

Cup corals do not seem to be a major problem here in the Virgin Islands as they seem to prefer the darker areas that other corals don’t like and I’ve not seen any great proliferation in all the years that I have been snorkeling around the Virgin Islands.

They are, however, a problem in the Gulf of Mexico where they tend to crowd out other native coral and sponge species. They especially like oil rig platforms where hundreds of thousands of colonies may be found attached a platform.

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