These communities are referred to as fouling communities due to their negative impacts on boats and other equipment left in the water. Animals of the fouling community form dense mats on the underside of boats which increases drag, reduces maneuverability and can even lead to the deterioration of wood, metal or fiberglass. The typical fouling community provides excellent habitat for various crabs, shrimp and small fish as well as good feeding grounds for larger fish like the sheepshead
Sea grapes have some very interesting characteristics that make them unique residents of our coast. For example, sea grapes are classified as members of the phylum Chordata, which includes vertebrates like fish, deer and elephants. However, sea grapes don’t actually resemble us vertebrates except during the larval phase in which they possess early developmental stages of a backbone and spinal chord. The larval stages of the sea grape are found free-swimming in the water column but the adult stages are described as sessile (permanently attached). Other sessile organisms include oysters and barnacles. Once these animals choose a place to settle down, they have made a lifelong commitment. Another interesting characteristic of sea grapes is that they are what scientists term hermaphrodites. This means that each individual possesses, at some point of its life, both male and female reproductive structures.
One of the most notable features of the sea grape is the two large siphons that are situated close together at the top of the animal. These siphons provide the sea grape with a continual supply of water that is full of food and oxygen. As the water is pumped through the animal, food is filtered from the water in the digestive system and waste products are flushed out. Food particles include microscopic plants, phytoplankton and microscopic animals, zooplankton. Sea grapes are tunicates, (cylindrical body enclosed in a tough outer covering)and have a translucent tunic that is firm but not rigid. Through the tunic you can see the major components of the digestive tract.
The next time you are on a floating dock take time to peer underneath and see the flourishing communities that are home to the sea grape.