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Sea grasses |
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Sea grasses are marine angiosperms (flowering plants). Just like their terrestrial relatives, sea grasses produce tiny inconspicuous flowers and pollen. Pollen is distributed by currents. They are very grass-like in appearance but are much more closely related to members of the lily family. There are approximately 50 species of sea grasses, mostly in tropical and subtropical habitats. There are, however, a few species found in colder climates. Sea grasses are generally restricted to muddy and sandy habitats. In the tropics, they are frequently associated with mangroves. One of the more dominant species in the Florida Keys is Turtle grass (Thalassia testudinum). Thalassia forms extensive meadows and is frequently found to depths of 10 meters. Thalassia produces a root-like horizontal stem that connects the erect blade-like shoots. These stems interdigitate forming a dense interwoven pattern. Sea grass beds play an important role in the environment for several reasons. First, the interwoven horizontal stems helps to stabilize the sediments. In addition, the dense upright shoots slows down water currents, allowing larvae and seeds to settle out of the water column. Sea grasses are also important because a number of organisms feed directly on the plants, including manatees, turtles and ducks. Sea grasses also have a number of epiphytic organisms that live on the blades and these organisms are frequently grazed on by a number of fish, mollusks, echinoderms, crustaceans and others. Dense sea grass meadows provide habitat for a variety of organisms and act as nursery areas for a number of commercially important species of fishes. Sea grasses also provide an important source of detrital material that many marine organisms consume.
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 Keys Marine Lab Boats
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