Flatworms belong to the phylum Platyhelminthes. The body of these worms are flattened from top to bottom, that’s why these worms are called flatworms. They are bilaterally symmetrical and triploblastic (having three germ layers) organisms but they lack a body cavity or coelom. The body systems such as digestive, muscular, nervous, excretory, and reproductive systems are developed. Examples are flukes, tapeworms.
<span>a. Acoelomates. Flatworm is a type of acoelomate animal; they have no body cavity or ceolom but they have </span>mesenchyme in their body cavity that surrounds the gut and organs in one solid body.
Given that the root equi- means "equal" and the Latin word nox means "night", the correct answer as to what the word "equinox" means is C. when the length of day and the length of night are the same.
