In this article we will discuss about the structure of obelia. This will also help you to draw the structure and diagram of obelia.
1. It is the slide of obelia, which is a marine, colonial and arborescent animal.
2. It is found attached to submerged objects like rocks and weeds etc.
3. All the individuals in a colony are attached through branches to a horizontal hydrorhiza. The branches are called hydrocauli.
4. Each branch bears three types of zooids – the polyp, the medusae and the blastostyles, thus making it polymorphic.
5. The polyp has a vase-like or bell-like body enclosed in a cup-like hydro theca. At its distall end lies distinct a raised area – the hypostome with an apical mouth surrounded with tentacles. It is the organ of feeding.
6. The medusae are saucer-shaped zooids and are produced in blastostyles.
7. The blastostyles or gonozooids are club shaped and are devoid of mouth or tentacles. They are enclosed in gonotheca.
8. Gonads are borne on medusae.
9. Life history shows alternation of generations and development through planula larva.