The sponge is considered the oldest animal phyla. They are multicellular, but have no tissues or organs. small pores are the gateway to a complex channel system where the sponge pumps a stream of water from which cells extract small particles of food.
Does the sponge have true tissue?
Unlike protozoa, sponges are multicellular. However, unlike higher metazoans, the cells that make up the sponge are not organized into tissues. Therefore, the sponge lacks true tissue and organs. Moreover, they have no body symmetry. However, sponges have special cells that perform certain functions.
How many tissue layers does the sponge have?
As mentioned above, the sponge is the ectoderm, which is essentially composed of two cell layers. Between these two layers is a gelatinous substance called mesohyl.
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