by B. N. Sullivan
This is the second in a series of posts intended to showcase the many colors and shapes of soft corals in the taxonomic family Nephtheidae.
In the first post I mentioned that these corals appear in a countless array of colors. Most grow as tree-like structures having a stem, or stalk, with many branches. Near the ends of the branches are clusters of polyps which open like tiny flowers when they are feeding. When the polyps are closed, they look like little beads.
In fact, when the polyps are retracted, these corals -- especially the greenish colored ones -- resemble broccoli plants, and "Broccoli Coral" is one of the common nicknames given to this type of coral. One look at the photo here, and you'll understand why. (Click on the photo to enlarge.)
Although this kind of coral can resemble broccoli in appearance, it definitely is not a plant. It is a colony of animals -- the coral polyps. The polyps arrange themselves in bundles at the ends of the rubbery stalks. Each polyp has exactly eight short, feathery tentacles. In order to feed, the polyps open and close their little tentacles, grabbing tiny nutrient particles that are suspended in the water.
Many Nephtheid coral colonies contract during daylight hours, making them look a bit shrunken and withered. They expand to feed at night, plumping themselves out and extending all of their little tentacles like bouquets of flowers at the tips of their stalks. For this reason, many of the best photos of these corals are taken during night dives.
I took the photo on this page in the Red Sea, during daylight hours. You can see that the polyps are tightly shut. In tomorrow's "Wordless Wednesday" post, you'll see some macro photos of this same variety of soft coral.