Kool if you know what I mean
The answer is an open system
Flatworm<span>, also called platyhelminth, any of the phylum Platyhelminthes, a group of soft-bodied, usually much flattened invertebrates. A number of </span>flatworm<span> species are free-living, but about 80 percent of all </span>flatworms are<span> parasitic—i.e., living on or in another organism and securing nourishment from it.</span>
