Title: Narwhal - Wikipedia
Headings: Narwhal
Narwhal
Contents
Taxonomy and etymology
Description
Tusk
Vestigial teeth
Genome
Distribution
Behaviour
Social
Migration
Diet
Diving
Communication
Breeding and early life
Life span and mortality
Predation and hunting
Conservation issues
Cultural depictions
In legend
In literature and art
Gallery
See also
References
Further reading
External links

Content: The rubbing of tusks together by male narwhals is thought to be a method of communicating information about characteristics of the water each has traveled through, rather than the previously assumed posturing display of aggressive male-to-male rivalry. In August 2016, drone videos of narwhals surface-feeding in Tremblay Sound, Nunavut showed that the tusk was used to tap and stun small Arctic cod, making them easier to catch for feeding. The tusk cannot serve a critical function for the animal's survival, as females — which generally do not have tusks — typically live longer than males. Therefore, the general scientific consensus is that the narwhal tusk is a sexual trait, much like the antlers of a stag, the mane of a lion, or the feathers of a peacock. Vestigial teeth
The tusks are surrounded posteriorly, ventrally, and laterally by several small vestigial teeth which vary in morphology and histology. These teeth can sometimes be extruded from the bone, but mainly reside inside open tooth sockets in the narwhal's snout alongside the tusks. The varied morphology and anatomy of small teeth indicate a path of evolutionary obsolescence, leaving the narwhal's mouth toothless. Genome
A 2.3 GB genome sequence has been assembled from multiple Illumina libraries. The geno