CLASSIFICATION OF GRANTIA
Found in Gulf of St. Lawrence. Common in Europe. Distributed from Rhode Island to Greenland.
HABIT AND HABITAT
Grantia is a small, solitary or colonial marine sponge found in shallow to approximately 60 fathoms deep in well oxygenated water.
GENERAL CHARACTERSTICS OF GRANTIA
- Complex vase-shaped body, measuring 20 to 25 mm in length and 5 to 6 mm in diameter.
- Each cylinder bulges in the middle and opens to the exterior by osculum. Body surface is covered by a ostia bearing membrane.
- At the distal free end there is a large osculum, encircled by a fringe of large giant monaxon spicules forming funnel-shaped collar or oscular fringe.
- Proximal and or base attached to substratum .
- Body wall is thick through which monaxon, triaxon and tetraxon spicules project.
- Body wall is composed of outer dermal epithelium, middle mesenchyma and inner flattened epithelium lining spongocoel which opens through the osculum.
- Canal system is syconoid. Choanocytes are restricted to radial canals. Course of water current is ostia -> prosopyles -> radial -> canals -> apopyles -> spongocoel -> osculum -> exterior. Nutrition, respiration and excretion by canal system.
- Reproduction by sexual or asexual methods. Asexual reproduction by budding and regeneration, while sexual by ova and sperms. Larva is amphiblastula.