They have the following general features They are large-bodied worms and are easily seen in situ at necropsy of infected hosts. Males have a copulatory bursa Most have large mouth openings and prominent buccal capsules which may contain teeth in some species. They use their buccal capsules in feeding, either by grazing the mucosal surface or by attaching to a plug of mucosa , drawing it into the buccal capsule and digesting it. Leaf crowns may be present as accessory cuticular structures around the opening of the buccal capsule. Most females of this group pass strongyle-type eggs .
Some species have life cycles that include extensive migrations through the bodies of their hosts.
Most are found in the large intestine but a few species occur in the respiratory and urinary tracts. Three families are important in domestic animals - Strongylidae , Chabertiidae and Syngamidae Strongylidae Members of this family are common in equines but they are also found in elephants, ostriches, rhinoceros, tapirs, tortoises, warthogs and marsupials. Their predilection sites include primarily the cecum and colon. The preparasitic phases of the life cycles are similar with strongyle-type eggs passing in the feces of infected hosts. Development to the infective, ensheathed third stage larvae may take as little as 7-10 days in a warm, moist environment.