Final answer:
Strongylus vulgaris, a large strongyle, feeds on the blood and tissue of horses in their intestines and is a type of parasitic roundworm.
Step-by-step explanation:
Strongylus vulgaris, known as a large strongyle, is a type of parasitic roundworm that belongs to the phylum Nematoda. These nematodes are commonly found in the intestines of horses, where they feed on the blood and tissue of their host, leading to a condition known as verminous arteritis which can be serious in horses. The life cycle of Strongylus vulgaris involves the larvae being passed through the feces of the host, developing on pasture, and then being ingested by another host, where they are able to mature into adult worms and complete their lifecycle.