BSc 1st Year Lower Non-chordates Obelia Sample Model Practice Question Answer Papers
Q. 2. Explain the division of labour by taking the example of Obelia.
Ans.2. Obelia is a colonial coelenterate which shows polymorphism. As a matter of fact, polymorphism is caused by the division of labour, because the structure of each zooid is related to the function carried out by the specific structure. For example, in Obelia, three different types of zooids are found to carry out different functions. These are :
1. Polyps or the nutritive zooids which nourish the colony. These contain mouth and a gastrovascular cavity. The polyp or hydranth catches the food and then digests it.
2. Gonangia or blastostyles are reproductive zooids and are concerned with asexual reproduction and produce free-swimming medusae asexually.
3. Medusae are sexual zooids and contain gonads. These produce sperm and eggs for sexual reproduction.
Thus we see that there is a well-marked division of labour in the Obelia colony. The colony bears and produces different types of zooids, each carrying a specific function.