Strongylidae

species of worm

Strongyloides (from Greek strongylos, round, + eidos, resemblance), anguillula, or threadworm is a genus of small nematode parasites, belonging to the family Strongylidae, commonly found in the small intestine of mammals (particularly ruminants), that are characterized by an unusual lifecycle that involves one or several generations of free-living adult worms.

Strongyles (from Greek strongulos 'round'), or alternatively, strongyls, are nematode worms of the family Strongylidae, order Strongylida. They are often parasitic in the gastrointestinal tract of mammals, especially grazers such as sheep, cattle, and horses.