Generally the term is "anatomy," the same as for humans.
Centrioles
that the animal once had a use for that structure depending on where it lived. or that it decended from an animal that had that structure and used it.
An insect is a type of animal. Any structure on an insect is, by definition, a structure on an animal.
The nucleus
Gland
The cytoskeleton is the structure that provides rigidity in an animal cell. It is made up of protein filaments such as actin, microtubules, and intermediate filaments, which help maintain cell shape and provide structural support.
Cell membranes are found surrounding both plant and animal cells
If by structure you mean organelles, then ribosomes.
Gland
no
The smallest structure within an animal is a cell. There are, in some cells, many smaller organelles and other structures.
This is similarity in structure of both animal and plant cell:Both plant and animal cell have a nucleusBoth have a cell membraneBoth have a cytoplasmBoth plant and animal cell contain ribosomes