Cup corals are non-reef building species that inhabit shaded vertical surface and caverns down to great depths.  There are only two species likely to be seen while scuba diving in Hawaii.  They rely upon capturing zooplankton as food and extend beautiful translucent tentacles at night.  Cup corals are also found in very cold water throughout the world.

Puako, Hawaii, 20 feet

Puako, Hawaii, 20 feet

Kaneohe Bay, Oahu, 10 feet

Night diving among ledges and cavern ceilings covered by Tubastraea coral is truly a macro photographer's dream-come-true.  These beautiful corals extend their 3/4 inch long tentacles to feed upon zooplankton at night.  During the day the tentacles are retracted into deep circular calices.  The outside of these calices are quite smooth and well-developed colonies are composed of many mouths.  Larger and more brightly colored than Oval Cup Coral.   Avoid spending much time under cavern ceilings where these corals live, since trapped air bubbles will cause everything to die.  If you are lucky, you may find a frilly orange sea slug preying upon the coral.

Haleiwa Trench, Oahu, 25 feet

Haleiwa Trench, Oahu, 25 feet

Mala Wharf, Maui, 15 feet

Maui Ocean Center

Rare in dark holes and overhangs at shallower scuba depths.

Haleiwa Trench, Oahu, 50 feet

Haleiwa Trench, Oahu, 50 feet

Haleiwa Trench, Oahu, 75 feet

Haleiwa Trench, Oahu, 75 feet

Haleiwa Trench, Oahu, 75 feet

Haleiwa Trench, Oahu, 75 feet

This species is often confused with the well-known Orange Cup Coral in Hawai'i.  It is uncommon in shallow water, limited to a few locations with large shady overhangs exposed to good water circulation, including the Haleiwa Trench and Koko Head.  Its orange, green, yellow, or cream calices are distinctly oval and septa extend outside of the cup.  Individual coralla are found very close to each other; they do not form small heads with several corallites.

Haleiwa Trench, Oahu, 75 feet

Haleiwa Trench, Oahu, 75 feet

Haleiwa Trench, Oahu, 25 feet

Haleiwa Trench, Oahu, 50 feet

Haleiwa Trench, Oahu, 25 feet

Haleiwa Trench, Oahu, 25 feet

Sharks Cove, Oahu, 25 feet

An uncommon species with individual cups connected by stolons only at the base.

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