Roundworms are triploblastic, which means their embryos have all three germ layers.
Yes, they have a head.
Their body cavity is called a pseudocoelom.
Yes they have segmentation.
A roundworm has no heart or formal blood vessel.
A roundworm has no formal respiratory system.
A roundworm has an anus at its rear end and a series of excretory tubes that end in an excretory pore.
A roundworm has two nerve cords that transmit impulses in the roundworm.
A roundworm reproduces sexually.
A roundworm has no skeleton.