Jellyfish have an outer layer called the epidermis; a middle layer made of a jelly-like substance called mesoglea; and an inner layer, called the gastrodermis. A very basic nervous system allows jellyfish to smell, detect light, and respond to other stimuli. Jellyfish have a digestive cavity that acts as both its stomach and intestine.
Sea angels are a type of gelatinous, transparent slug. Sea angels will grab their prey and eat them through the protrusions on their head. The protrusions, called buccal cones, have hooks and a kind of toothed-tongue on the inside. Their organs are colorful and can be seen through their transparent bodies.
This creates a jet propulsion allowing the scallop to swim short distances.
Giant clams are sessile meaning they stay in place on the sea floor.
They can use them taste, grab, and smell things.