a small mouth, such as would be found in the classic
SPS coral, almost always means tiny food is eaten. Such
food may be living or dead, however. Recent research has
shown that many corals are dual-purpose feeders. During the day they eat small detrital particles, fish feces,
and particulate organic material. At night they feed on
small, live, bottom-bouncing (or demersal) plankton.
Such animals also often have the capability of ingesting
bacterial particulates. As bacteria have a higher nitrogen-to-carbon ratio than do most detrital particles, they are a
good food source to build protein.
However, one can’t always depend on the obvious.
Many small gorgonians apparently do not eat any small
particulate material, no matter what it is, and they par-
ticularly do not eat any bacteria. Although such animals
would appear to be natural candidates for the title of bac-
terial particle feeders, they simply do not eat it. Instead,
they are specialized to capture small living zooplankton
and detrital particulate material, made of mucus and al-
gal fragments that is about a tenth of a millimeter in
diameter. In an aquarium, these animals do very well on
diets of enriched newly hatched brine shrimp, and small
commercial particulate foods.