Colonial alga: Volvox

Explanation:

Colonial algae are those algae which form colonies by the aggregation of individual cells. Each cell of the colony is similar in structure and function. Volvox is a colonial alga, which belongs to the family Volvocaceae of the Chlorophyta division.

Features of Volvox:

- Volvox is a green, freshwater colonial alga that forms spherical or oval colonies.
- The colony is composed of thousands of individual cells, which are arranged in a single layer on the surface of a gelatinous matrix.
- The cells are flagellated, that is, they possess hair-like structures called flagella, which help in the movement of the colony.
- The colony is hollow, with an opening at one end called the anterior pole, and a smaller opening at the other end called the posterior pole.
- The cells of the colony are specialized, with some cells performing photosynthesis, while others are involved in reproduction or movement.

Reproduction in Volvox:

- Volvox reproduces asexually by the formation of daughter colonies within the parent colony. These daughter colonies are released from the parent colony when they are mature.
- Volvox reproduces sexually by the fusion of gametes. The male gametes are small, non-motile cells, while the female gametes are larger, motile cells. The fusion of these gametes results in the formation of a zygote, which develops into a new colony.

Significance of Volvox:

- Volvox is an important model organism for the study of cell differentiation, development, and evolution.
- Volvox is also used in aquaculture as a food source for fish and other aquatic animals.

Therefore, Volvox is an example of a colonial alga, which has unique features and significance in the field of biology.