4. Nematodes Nematodes have a versatile body with no blood. They are microscopic worms that belong to the Phylum Nematoda which are often referred to as pinworms, roundworms, hookworms and whipworms.

But virtually all other cells have a primary cilium. Likewise, for many years it was generally assumed that the entire phylum Nematoda, comprising roundworms, completely lacked cilia or flagella.