The spiral tusk of this cetacean that inhabits the waters of the Arctic Ocean may reach a length of 10 feet
The tusk grows throughout the narwhal's entire life, commonly reaching... [DOC] [TLE] The narwhal (Monodon monoceros), a cetacean of 15 feet or more ... [PAR] The narwhal (Monodon monoceros), a cetacean of 15 feet or more in length, has 
a surprisingly sensitive tusk ranging from six to 10 feet long | See more about 
Narwhals.