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
|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.|