Biological and Ecological Information
Seagrasses are the flowering plants grown in the sea with shallow water where sunlight can penetrate. Scientists believe that seagrasses are originated from the single-cell living things, called diatom, living in the sea. Later, they evolutionarily developed themselves to terrestrial plants like mosses, ferns, and cycads, which are highly plant species during the reduction of dinosaurs’ population. Many millions years ago, terrestrial flowering plants are resulted from the evolution reaching to the maximum stage (Waycoott et al., 2004). Meanwhile, seagrasses are only one plant species that returned to grow in marine environment (Monocotyledons, sub-class Alismatidae). Seagrasses are distributed widely in shallow water zone and coastal areas all over the world in tropic and temperate zone. Seagrass has two modes of reproduction, asexual and sexual reproduction. Budding or regeneration of original rhizome are as asexual reproduction, whereas sexual reproduction will develop flower and pollen which is transferred by water current and wind. After fertilization, the flower is developed to fruit containing seeds which can be further sprouted and grown. External structure of seagrass is similar to terrestrial grasses consisting of three parts as follows:
Root is used to absorb nutrients and minerals from soil and help attach with sea bottom for it stability.
Rhizome is the part of trunk that grows within sea bottom.
Leaf blade is used for photosynthesis, different shapes depending on the types of seagrass. There are both flat leaf and tube. Characteristic of seagrass leaf is used to identify seagrass species.
Figure 2 Structure of seagrass