Flatworms, including Tapeworms and Flukes, breathe and eat literally through their skin. Flatworms feed on the blood, tissue fluids, or pieces of cells inside the bodies of their hosts. Flatworms can live internally on humans and infect the blood and organs. Flatworms range in size from being microscopic to some over 20 metres long for example in the whale tapeworm.
Roundworms, include Pinworms, Threadworms, Hookworms, Ascaris (a word that literally means ‘intestinal worm’) and Heartworms. They have hollow bodies and openings at either end and generally grow between 2-5 inches long. Roundworms are very commonly found in pets and animals such as dogs and cats and can be easily passed on to humans. Roundworms live in salt water, fresh water and the soil.
Eating contaminated foods or getting worms from contaminated pets is the most usual way to get roundworms (a category of worms). Hookworms and pinworms are often the most common types of roundworms found in humans.