Which of the following parasites are also called blood worms?

The term “blood worms” refers specifically to certain species of strongyles, which are parasitic worms that inhabit the intestines and blood vessels of various animals, particularly equines. Strongyles are known for their significant impact on the health of horses, as they can cause anemia, colic, and other serious health issues. The larvae of some strongyles migrate through the bloodstream to various tissues, which is likely where the nickname "blood worms" originates, as these parasites can be associated with blood loss and vascular issues.

In contrast, ascarids are a different group of roundworms that primarily affect the intestines and do not share the same features or health implications associated with blood. Tapeworms are segmented parasites that can also inhabit the intestines but are not known as blood worms. Roundworms is a broad term that includes various types of worms but does not specifically denote the blood-feeding behavior seen in strongyles. Therefore, strongyles stand out due to their particular life cycle and the health challenges they pose, justifying their designation as "blood worms."