Final answer:
Dictyocaulus viviparus is a type of parasitic worm, known as a helminth, affecting the respiratory system of livestock and causing lungworm.
Step-by-step explanation:
The organism Dictyocaulus viviparus is a type of parasitic worm. Specifically, it is a nematode that affects the respiratory system of livestock, especially cattle, causing a condition often referred to as 'lungworm'. The lifecycle of Dictyocaulus viviparus involves larvae being ingested by the host, then developing into adults within the animal's lungs.
The adult worms live in the host's respiratory tract and can cause significant health issues such as coughing and respiratory distress, which if left untreated, can lead to severe complications or even death of the host animal. This parasite is an example of a helminth, which generally refers to multicellular parasitic worms that can cause disease in their hosts.