Answer the following question given this paragraph: 

Roundworms make up the phylum Nematoda. They have a pseudocoelom and hydrostatic skeleton. Their body is covered with tough cuticle. Free-living roundworms are found mainly in freshwater habitats. Parasitic roundworms have a variety of hosts, including humans.


Q: What has a pseudocoelom and hydrostatic skeleton?


A:
roundworms