Sponges have specialized cells and an endoskeleton, but they lack tissues and body symmetry. ... They include jellyfish and corals, both of which have radial symmetry. All cnidarians have nematocysts, and many are bioluminescent. They may exist in medusa and/or polyp form.
Answer:
Explanation:
This is because the sieve plate interconnected like that help in exchange of substances or transport of substances between element cell and it act as a barrier to prevent the sap from been loss when phloem is damaged or cut. The sieve plates form the sieve tube which is the conducting element of the phloem. It is formed from series of elongated cells that are interconnected by perforations in their walls.
Could you ask again but with more details? I do not understand.