Sea Pens: Wild Hosts

Sea pens are a special group of octocorals that live in sandy bottoms. A sea pen has a foot that keeps it anchored into the sand and an above ground rod that contains the feeding coral polyps. Many sea pens are beautifully branched, creating a shape reminiscent of a quill pen. Although most are nocturnal, some emerge from the sand during the day. One of Gorontalo’s muck sites is home to at least four very different species of sea pens. Only one of them appears in marine life books, the large Lemon sea pen (Pteroeides sp.).

A photograph of one sea pen caught the eye of a researcher friend, its maroon axis edged with white spicules. Miguel’s Diving staff knows right where a large patch of these emerge on overcast days. Of the sea pen species found here, this maroon one tends to host more marine life than others. To help our friend, we braved rough surf to locate these unusual soft corals. On the maroon ones, we found at least two species of commensal crabs hiding amongst the branches, a shrimp or two, and a very active maroon worm. With the surge being felt as deep as 20 meters, none of the pictures of the maroon beauties were in focus. Over the next two months, the winds will shift to the west, leaving calm seas and other opportunities to visit these beautiful corals.