Varicose veins are large, raised, swollen blood vessels that twist and turn. They usually develop in the legs and can be seen through the skin. Spider veins are smaller, red, purple, and blue vessels that also twist and turn. Spider veins are easily visible through the skin, as well.
Common name: Flatworms. 1  Scientific name: many species. Phylum: Platyhelminthes. 2  Description: Although they are called Flatworms, these invertebrates are not flat. They are round-bodied with a flat belly. 3  Fun facts: A Flatworm has a single opening to its stomach, in the middle of its underside.
The following are the three classifications: 1  Annelida â This group is probably the most recognized of the three worm classifications. 2  Nematoda â This phylum of worms includes roundworms, hookworms and threadworms. 3  Platyhelminthes â The worms in this group are flat or ribbon-shaped. Nematoda â This phylum of worms includes roundworms, hookworms and threadworms. 2  Many roundworms are parasites and can cause a variety of problems for people and pets. 3  Threadworms live on the ground in damp soil, mossy areas or in decaying vegetation. 4  They can also be found in freshwater and saltwater.