Commensalism and Parasitism

The brainworm (Parelaphostrongylus tenuis) is a parasitic nematode which resides in taiga. Its natural host is the white-tailed deer (Odocoileus virginianus). In other words, the brainworm uses the deer as a home and a place to reproduce without adversely affecting it. This is an example of commensalism. Both species live throughout North America, including much of Canada and northern America.

When the brainworm first hatches, it grows in the brain of the white-tailed deer. As a larvae, it then exits the animal through feces. Next, it infects gastropods such as snails and slugs. There it becomes mature. When an ungulate accidentally ingests an affected gastropod, the brainworms travel through the spinal cord to the brain, causing severe illness. Therefore, the brainworm is also a parasite. In taiga, the brainworm most often affects the moose, causing moose sickness.

 

 45°56'15.94"N
 68° 6'38.46"W