The Right Blue

Octocoral polyps - Little flowers of the sea

Open polyps on a Nephtheid soft coral

by B. N. Sullivan

Octocorals (Octocorallia) are a subclass of corals whose polyps have eight tentacles. The name Octocoral derives from this morphological feature [in Greek, "okto" means "eight"].

When the polyps are feeding, the feathery tentacles are spread wide to capture passing bits of nutrients. In macro photos of Octocorals, like the one above, the open polyps look like a dense garden of little flowers.

When the coral polyps are not feeding, the tentacles retract into little balls, like an open hand closing into a fist. To see what I mean, look at these recently posted macro photos of another soft coral with closed polyps.

The Octocoral species pictured above is a a Nephtheid soft coral. I took the photo at Indonesia's Bunaken National Park, a lush marine preserve near the northern tip of Sulawesi Island.

Ocellaris Clownfish -- The Model for Nemo

Clownfish (Amphiprion ocellaris) - Pulau Sipadan, Malaysia

by B. N. Sullivan

The clownfish species in the photo on this page is Amphiprion ocellaris. This species was the model for the Disney/Pixar animated character Nemo, although there are some 30 species of clownfish living in the tropical seas of the Indo-Pacific region.

Clownfish are known also as Amemonefish, after their habit of making their homes among the tentacles of sea anemones. Each species of clownfish lives preferentially in certain anemone species. The Ocellaris clownfish in the photo above is snuggled into an anemone called Heteractis magnifica. This anemone appears to be the preferred abode of this fish species, although some Ocellaris clownfish can be found living in anemones of the genus Stichodactyla.

At Peace in the Deep Blue

Diver swimming along a deep wall in the Red Sea

Looking through some old underwater photos, I came across the evocative image above. The photo had been squirreled away for years, but the moment I looked at it memories of the peace and serenity of deep dives flooded my mind. It's quiet down there in the deep blue.

One Big Butterflyfish!

by B. N. Sullivan

Lined Butterflyfish (Chaetodon lineolatus)

This is the Lined Butterflyfish (Chaetodon lineolatus), perhaps the largest butterflyfish species in the world. Adults measure about 30 cm (12 in) in length -- nearly twice the size of the majority of butterflyfish species. The Saddle Butterflyfish (C. ephippium) is the only other butterflyfish species that approaches (and may sometimes match) the size of C. lineolatus.

This is an Indo-Pacific species widely distributed throughout the region. We have seen them in the Red Sea and in Hawaii, but they are known to occur as well along the shores of East Africa, Southern Japan, and Australia's Great Barrier Reef.

We have observed them almost always in pairs. They hang out around coral reefs, which is not surprising since they feed primarily on coral polyps. It is not unusual to see a pair of these fishies bobbing along side by side as they peck away at a coral head. According to the World Register of Marine Species (WoRMS) page on C. lineolatus, they also feed on anemones, small invertebrates, and algae.

Lined Butterflyfish are believed to be a long-lived species. Although no one knows for sure how long their natural lifespan is, it is likely several decades. In places like Hawaii where local divers may visit the same site again and again over years or even decades, the divers learn to recognize individual animals that live there. We got to know a certain pair of C. lineolatus living in Honaunau Bay, on the South Kona coast of Hawaii Island and have seen them there again and again over a period of at least 15 years.

Honaunau Bay is a popular snorkeling and shore-diving spot for tourists as well as locals, and many have fed the reef fish there over the years. While guides and tour operators currently do a good job of discouraging this practice, the fish seem to have long memories. The pair of Lined Butterflyfish in the image below still approach divers, ever hopeful for a hand-out.