Question

Gonads of Obelia occur

• A. In hydrocaulist age and indefinite in number
• B. Bases of tentacles of medusa and 8 in number
• C. On blastostyles and 8 in number
• D. On radial canals, oral surface of medusa and four in number

Answer 1

The correct option is D On radial canals, oral surface of medusa and four in number

The sexual form of Obelia consists of bell-like medusae which bear gonads. A fully grown medusa is radially symmetrical umbrella-shaped structure with a diameter of 1 or 2 mm. These basically have four radially and a marginal circular canal. Gonads are situated on these four radial canals present on the subumbrella surface. These gonads are responsible for dispersion of sperms and ova in water.

So, the correct answer is option D.