Cnidarians have two types of body forms, viz., polyp and medusa.
- The polyp is cylindrical and usually fixed. It represents the asexual stage.
- The medusa is umbrella like and usually free swimming. It represents the sexual phase.
Polyp vs Medusa
Polyp
|
Medusae
|
| 1. Fixed, rarely free, found near water mark attached to rocks. | 1. Free swimming, found in open waters. |
| 2. Body cylindrical with a long stalk (Hydra). | 2. Body saucer shaped, umbrella like with a reduced stalk (Jellyfish). |
| 3. Body attached below so that manubrium is directly upward. | 3. Base above so that manubrium hangs downward. |
| 4. Velum is absent | 4. Velum is present. |
| 5. Sense organs absent | 5. Statocysts present at the bases of eight adradial tentacles. |
| 6. Gastrovascular cavity simple without radial and circular canals. | 6. Gastro vascular cavity represented by stomach, four radial canals and one circular canal. |
| 7. Gonads absent. | 7. Four gonads on radial canals. |
| 8. Reproduces asexually by budding. | 8. Reproduces sexually by gametes. |
| 9. Concerned with feeding, protection and asexual reproduction. | 9. Concerned with sexual reproduction. |