Pinworms belong to the group of worms called the Nematodes which is the answer. Pinworms are intestinal roundworms living in the intestinal tract of animals and human. There are 4 types of pinworms and one of it is Enterobius vermicularis which then infects the humans.
The surface layer of the water freezes solid creating a barrier that insulates the ice below so that it keeps a steady temperature usually a few degrees above freezing (32 degrees).
The organs are known as Vestigial organs. The evolution from land-dwelling animal to the marine animals has led whales as well as dolphins, to lose hind limbs. The pelvic and leg bone serves no purpose in them and just provide the anchorage to muscles
