How many tissue layers do porifera have?

Question

How many tissue layers do porifera have?

Answer 1

Sponges are the simplest form of multi-cellular animals. They are very diverse and come in a large variety of colours, shapes and structural complexities. They range in heights of 1-200cm and in diameters of 1-150cm. They have partially differentiated tissues, and not true tissues. Sponges don’t have internal organs. They don’t have muscles, a nervous system, or a circulatory system. Their walls are lined with many small pores called ostia that allow water flow into the sponge.    

The structure of a sponge is simple. One end is attached to a solid such as a rock while the other end, called the osculum, is open to the environment. Sponges are able to get microorganisms such as algae and bacteria for food through openings. Some sponges are carnivorous and use their spicules to capture small crustaceans.

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