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South Florida Aquatic Environments

Seagrasses




LIFE IN THE SEAGRASSES

Starfish - Oreaster reticulatus
© Don DeMaria
Seastar


Seagrass life:

Invertebrates

Invertebrate fauna living in seagrass habitats represents a diverse group. Seagrasses provide a rich source of food for invertebrates, primarily in the form of epiphytes.

Mollusc in Sand Adjacent to Turtle Grass
© Cathleen Bester/FLMNH
Horse Conch

Epibenthic organisms reside on the surface of the bottom sediments. Some epibenthic invertebrates feed on both the epiphytes living on the seagrass blades as well as the blades themselves, such as the queen conch (Strombus gigas). Other epibenthic species, including the Bahamian starfish (Oreaster reticulatus) and various gastropods, feed on infaunal organisms found living within the sediments. Feeding on detritus, epiphytes, and seagrass blades are various sea urchins that move from nearby reefs to feed in the seagrasses at night. Another echinoderm, the sea cucumber (Holothuria floridana), moves slowly along the surface of the sediments ingesting sand grains and algae. Pink shrimp (Paneaus duorarum) and juvenile spiny lobsters (Panulirus argus) find refuge among the blades of seagrasses.

Spiny Lobsters
courtesy Paula Whitfield, NOAA
Queen Conch

Epiphytic organisms, dominated by gastropods, are common throughout turtle and shoal grass habitats. These include anemones, bryozoans, and sponges, suspension feeders that live attached to the blades of seagrass. Without the dramatic increase in surface area provided by the seagrasses, the diversity of epiphytic organisms would be much lower.

Stony Coral Within a Seagrass Meadow
courtesy Florida Keys National Marine Sanctuary
Seagrass and Coral

Throughout shallow turtle grass communities, small patches of stony corals are common. As water depth increases, sponges become more common and may be found growing among the seagrasses or attached to dead coral skeletons.

Although not obvious, infauna communities thrive within the sediments of seagrass beds. The rigid pen shell (Atrina rigida), along with many other bivalve molluscs, is a common filter feeder found within the sediments of many seagrass beds.