Physical 

Eel Grass has long, flat leaves, and can reach up to 3 feet in length; it grows in dense mats and has a complex root system.  It has inconspicuous flowers on the base of the leaves.

Image by Colin Faulkingham from Wikimedia

Habitat

 Z. marina grows in various substrates in a wide range of salinities, commonly in bays and sounds.  The dense groupings of plants provide refuge for juveniles of various species.

Feeding 

Eel Grass is a marine vegetation.  It is photosynthetic, and thus autotrophic.