Demystifying the Narwhal’s Tusk

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Photo Credit: National Geographic

Yet again drones have proved an invaluable instrument for new discoveries, especially when it comes to observing marine mammal behavior (see my past post: Whale Tales – Current Cetacean Communiqués).  The subject in question this time is the strange and elusive Narwhal.

Humans have valued Narwhal tusks for centuries, perceiving them as a cure for a number of medical ailments including epilepsy and poisoning, a practice which is still alive and well in Japan. Inuits still carry on the tradition of culling narwhal for subsistence and often used the tusks for carving. However, we have had little knowledge about the value of the tusk to the animal itself until recent years. More current research and observation suggests the tusks of narwhals function in multiple capacities.

The edited footage above conveniently highlights moments where individual narwhals stun passing cod with a solid tap of their tusk. It’s an interesting hunting method, but one that is rivaled by other examples in the marine world. Many species immobilize their prey; some, like sailfish, use similar techniques, while others may use contrasting tools. Electric Rays and eels shock their quarry, while pistol shrimp use high-speed cavitation bubbles to daze their targets. Archer fish knock their dinner out of overlying branches by spitting a stream of water at them.

The purpose of the narwhal’s tusk likely doesn’t stop at clubbing unwitting prey. The absence of an enamel coating on their tusk supports the idea that these animals might be using them in a sensory capacity, allowing the specialized tooth to come into contact with surrounding water masses to detect environmental changes such as salinity and temperature, as well as chemical cues in the water associated with food and mates. Pairing this awareness of their surroundings with highly directional echolocation also allows them to find sometime slim openings in Arctic ice coverage where they can surface and breath as needed.

However, these animals may still suffer catastrophic events living in the extremes they do. Pods of narwhals occasionally suffer entrapments when rapidly shifting weather conditions cause unexpected freezing over potential air holes leading to open water. Kristin Laidre, a researcher at University of Washington’s Polar Science Center, noticed the frequency and timing of those events may be changing with recent shifts in Arctic climate. This, paired with a variety of additional stressors to the whales’ habitat, is the focus of one her current research projects examining the behavioral ecology of narwhals in a changing Arctic. She and other researchers have tagged the animals on multiple occasions in Canada’s Baffin Bay to track their movement, the depth of their dives, and associated water temperatures. As it turns out the temperature data has proved useful to other scientists interested in climatology data. Laidre is soon hoping to once again utilize the oceanographic power of narwhals, this time in Greenland.

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Discovery from the Otter Side

While this is an amazing story, the urge to not post all the otter jokes is a fight I may lose.

Sherlotter Holmes and John Beaverson

All joking (briefly) aside, the Journal of Systematic Palaeontology just published findings about the otter species Siamogale melilutra as described by Wang et al. Skeletal pieces from three individuals were recovered in western China and used to characterize the ancient otter who outguns the giant river otter of today in size (approximately 50 kg to the giant otter’s 34).

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Giant River Otter. Photo Credit: Ernane Junior, Your Shot, National Geographic

While the specimens had elements reminiscent of both otters and badgers, a few distinctive features allowed researchers to place the animals firmly in subfamily Lutrinae, home to 13 current day otter species. However the paper notes the mixture of characteristics, described in some other genera as well, lead to some interesting questions about the ways in which the two may be related.

On the tail of this amazing find, I share an interesting otter fact which upon learning some years ago, quickly escalated their status in my heart: sea otters have loose folds of skin under their arms they use as pockets for storing food and rocks to use as tools.

I will close with the following video as it would be an otter shame not to:

Speck of Science – 1/7/2016: Aye Calypso

Sometimes I come across some interesting news item that I don’t have time to write about in depth but still want to share. I’ve decided to start a new Speck of Science feature on my blog as a way to share brief blips and recaps of internet curiosities and dispatches.

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Today’s item is an article from the Guardian reporting that Jacques Cousteau’s ship, the Calypso, will soon be ready to begin life anew. The ship was downed by an accident and since 2007 had been languishing in a sort of boatyard purgatory due to disagreements over payment and the purpose of its restoration. This is truly exciting news for the continuing legacy of marine exploration, and our care for the world’s oceans.