Question

Choose the correct answers from the alternatives given.
Which of the following is not a characteristic of sponges?

• A. Sessile filter feeders
• B. Body wall has two cell layers
• C. Water enters through a single cavity the osculum
• D. Amoeboid cells digest food and make skeletal fibres and gametes

Answer 1

The correct option is C Water enters through a single cavity the osculum

Sponges (poriferans) are very simple animals that live permanently attached to a location in the water - they are sessile as adults and hence filter feeders. The body of a sponge has two outer layers separated by an acellular (having no cells) gel layer called the mesohyl.The amoeboid cells in sponges are in a semi-solid middle layer of the sponge. They engulf and digest food as well as secrete a material that helps to keep the sponge flexible. But, water enters into the spongocoel through numerous pores, or ostia, that create openings in the body wall. Water enters the projections directly through pores, makes its way into the central cavity, or spongocoel, and leaves by way of an osculum. The water is expelled through the osculum after passing through a system of excurrent canals and cavities lined with pinacocytes.

So, the correct option is, 'Water enters through a single cavity the osculum'.