Spirurida

noun plural

Spi·​ru·​ri·​da spī-ˈru̇r-ə-də 

: an order of parasitic nematodes of the subclass Aphasmidia that are characterized by an esophagus divided into two cylinder-shaped regions and having six lips and no buccal stylet and that include various parasites (as the filarial worms) of vertebrates having complex life cycles requiring an invertebrate intermediate host