column spacer Nutrition
Herbivory hot buttons for nutrition part of BCCR hot button for primary productivity part of BCCR hot button for carnivory part of BCCR hot button for Corals: a case study part of BCCR hot button for herbivory part of BCCR hot button for detrivory/bacterivory part of BCCR
There are 4 major trophic levels on a reef, with herbivory being considered here. Information on the others, including "Corals: a case study" (corals use all trophi modes), can be accessed via the icons.
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of seagrasses and seaweeds taken from a video

"Energy enters the reef ecosystem in several ways. But a major route is via photosynthesising plants, such as the seagrasses we see here, and seaweeds. There are even seaweeds growing on the blades of the seagrasses. Oh!...this is a nice rich growth of seaweeds, isn't it?" - Little Cayman 2001

NOTE possibly Thalassia testudinum


Herbivory: phytoplanktivores (phytoplankton-eaters)

hot buttons for herbivory part of BCCR hot button for algivores section of BCCR hot button for phytoplanktivores section of BCCR hot button for seagrass-eaters section of BCCR
There are 3 main types of herbivores on coral reefs. This section deals with phytoplanktivores; information on seagrass-eaters and algivores is available via the icons.
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of an ocean triggerfish taken from a video

"This ocean triggerfish is swimming in what seems like clear water, but is really a thin soup of microorganisms. The smallest are photosynthesising plant cells known as phytoplankton, but there is also a variety of small animals known as zooplankton." - Turneffe Island 2001. Video courtesy Andy Stockbridge, Belize

NOTE Canthidemis sufflamen

Phytoplankton is made up of a variety of single-celled photosynthesising organisms that drift passively in the surface region of the ocean. Energy flows from the sun to the phytoplankton and thence to a number of different types of zooplankters which eat the phytoplankton.  Common phytoplanktivores are copepods and many different types of invertebrate larvae.  


drawing showing phytoplanktivores around coral reefs

Many types of zooplankton eat phytoplankton, with copepods and mysid shrimps being some of the more common ones. Mysids are also known to eat coral-produced mucus-detritus. Gottfried & Roman 1983 Mar Biol 72: 211. Drawings modified fromHardy 1956 The open sea. Collins, London. Photograph of Calanus sp. courtesy Elaine Humphrey, University of British Columbia. photo composite of copopods and mysids
Larvae of many reef invertebrates also feed on phytoplankton using ciiated bands or fine bristle-sieves to collect and funnel the plant cells to the mouth. All images are approximately 50X life size.  
photograph of polychaete larva photograph of barnacle larva photograph of sea-star larva photograph of sea-cucumber larva photograph of sea-urchin larva
Early stage polychaete larvae showing bristles The nauplius larva of a barnacle feeds on phytoplankton The bipinnaria is the first of 2 larval stages of a sea star The convoluted ciliary bands of a sea-cucumber auricularia are easily seen The 2-armed pluteus larva of a sea urchin
Phytoplankton is eaten by a wide variety of bottom-dwelling invertebrates on the reef including tubeworms. photo collage of phytoplanktivorous Caribbean tubeworms
photo collage of Caribbean Clavelina tunicates Tunicates filter out bacteria and small-sized phytoplankters by straining the seawater through a fine-mesh mucous net. The food-laden mucus is then taken into the esophagus and digested.
Crinoids extend their arms into the current in order to filter out phytoplankton and other small organic food-particles. The arms have many side-branches called pinnules, and these pinnules bear rows of tube feet. The material is initially caught up on the sticky mucus of the tube feet, passed into a ciliated groove on a pinnule, moved into the main food groove on the arm, and then carried down this groove to the mouth. photo collage showing aspects of feeding of Davidaster crinoids
photo collage of a gorgonian and its phytoplankton food Gorgonians eat phytoplankton as well as protists and small zooplankters. Ribes et al. 1998 Limnol & Oceanogr 43: 1170.
As in other colonial cnidarians, such as corals, each polyp in a gorgonian is interconnected to adjoining polyps via extensions of the digestive cavities. Each polyp has a mouth surrounded by tentacles containing nematocysts for catching the prey, and each mouth can feed independently.  
photo collage showing gorgonian polyps, one of them having just eaten