Write short notes on sponges? And its significance.

1.	Write short notes on sponges? And its significance.
Answer» Absence of nervous and muscular tissue indicates that sponges must have been one of the earliest forms in the course of evolution. Absence of tissues indicate that the body organisation would have been at cellular level only without cells forming compact tissues. Further this also indicates that sponges do not show locomotion since they have no means of evaluating the surrounding because they lack muscular tissue. They are sedentary since they lack muscular tissue

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