copula - an equating verb (such as `be' or `become') that links the subject with the complement of a sentence. copulative, linking verb. verb - a content word that denotes an action, occurrence, or state of existence.
Different species of crabs eat different foods. Depending on the species, they may eat plankton, worms, shrimps, prawns and other shellfish, and they scavenge for animal and/or plant remains. 1  They are detrivores. 2  They will consume animal as well as plant matter (algae, etc.).
The answer to the question what do fiddler crabs eat? is that they are scavengers and feed on organic matter that are found on the surface of rocks and mud. Their diet consists of algae, microbes, fungus, or other decaying detritus.