All insect muscles are striated, even those involving the digestive tract and heart. Even muscles that cling tightly to the exoskeleton.
The small size of the insects combined with the number of striated muscles they possess, guarantee part of their success by allowing movements such as walking, jumping far greater than their length, carrying weights over 20 times their own, flying at sometimes very long distances, quick location of partner, or food and swimming.
The vinegar would tend to diffuse into the agar blocks decreasing the amount of vinegar outside the agar cubes and increasing the volume of agar cubes. Diffusion<span> is the movement of particles (ions or molecules) from an area of higher concentration to an area of lower concentration.