Then write how sponges an Cnidarians are alike and different?

Differences:

Cnidarians have groups of similar cells that work together as tissues, while sponges have no tissues, only disconnected regions of specialized cells.

Similarities:

They contain nematocyst (cells that sting)  

some are sessile/free swimming  

Some corals have a symbiotic relationship with algae, they need to grow in shallow waters so that light can penetrate for the algae to photosynthesize.

answer; i believe that the correct answer is (light);

there are mainly three domains in biological classification namely; archaea, bacteria, and eukarya.

archaea includes all the prokaryotic cells which are characterized by their lipid membranes. they have branched hydrocarbon which is attached to glycerol through an ether linkage.

bacteria includes all the prokaryotic cells, the cell membrane of which are made up of the unbranched fatty acid chain. in addition, they are attached to glycerol through an ester bond.

eukarya includes all the eukaryotic cells, that is, the cells contain a nucleus and other membrane-bound cell organelles.

they can be autotrophic as well as heterotrophic, unicellular as well as multicellular

they include kingdoms like protista, plantae, animalia, fungi et cetera.

read more on -

explanation: