3. Shell is oval and rounded without an operculum.
4. Head is distinct and bears a pair of stout, sensory tentacles and eyes.
5.Foot is ventral, broad and flat used for creeping and adhering.
6. True mantle cavity is restricted anteriorly and the ctenidia or gills have disappeared.
7. Secondary mantle cavity extends all round between the foot and mantle and contains a series of pallial gills or secondary branchiae for respiration.
8. Radula is composed of very few, strong hooked teeth in each row.
9. Heart with single auricle.
10. Nervous system shows little concentration towards the head region.
11. Patella is eaten by the poorer class in several countries like France, Italy and Ireland.
12. The shells of patella are used as decoration pieces.
Source:
1. Practical Zoology Invertebrates by S.S.Lal. 2. A Manual of Practical Zoology Chordates by Dr. P.S. Verma.
