What is the advantage of colonial animals in structure with unicellular ones?

Colonial organisms include both protozoa, which, uniting in colonies, create the appearance of multicellularity, and real multicellular animals, just in this case, not one cell, but the whole organism plays a specific role.

One of the advantages of this existence is the division of responsibilities between cells (in protozoa) or individuals (in multicellular organisms). If the cell of a single protozoan performs all the functions of a living organism, then in the colony the responsibilities are divided, it is more beneficial energetically. Also, being in a colony increases the chances of survival.