Marine Life & Conservation
Narwhal’s tusk is super sensitive
Narwhals’ distinctive long tusks are super sensitive, research has found.
The whales are known for their tusks which can reach 2.6m (9ft) in length, earning them comparisons with mythological unicorns.
The tusk is an exaggerated front tooth and scientists have discovered that it helps the animals sense changes in their environment.
Experts suggest males could use the tusks to seek out mates or food.
The results are published in the journal The Anatomical Record.
Dr Martin Nweeia from the Harvard School of Dental Medicine, US, undertook the study alongside an international team of colleagues.
Through the years, many theories have tried to explain the function of the narwhal’s impressive tusk.
“People have said it’s everything from an ice pick to an acoustic probe, but this is the first time that someone has discovered sensory function and has the science to show it,” said Dr Nweeia.
More recently, experts have agreed that the tusk is a sexual characteristic because it is more often exhibited by males and they appear to use them during fights to assert their social hierarchy.
But because the animals are rarely seen, the exact function of the tusk has remained a mystery.
Previous studies have revealed that the animals have no enamel on their tusk – the external layer of the tooth that provides a barrier in most mammal teeth.
Dr Nweeia and the team’s analysis revealed that the outer cementum layer of the tusk is porous and the inner dentin layer has microscopic tubes that channel in towards the centre.
In the middle of the tusk lies the pulp, where nerve endings which connect to the narwhal’s brain are found.
“Although it’s a rigid tooth, it has a very permeable membrane,” said Dr Nweeia.
He explained that because of this structure, the tusk is sensitive to temperature and chemical differences in the external environment.
The researchers proved the link when the tusk was exposed to different salt levels in the water and there was a corresponding change in the narwhal’s heart rate.
He described the tusk as “unique” in the animal kingdom because its porous outer layer is usually only found below the gum line in mammals, where it is only exposed by damage or disease.
“The narwhal is the only example documented where teeth are shown to have the ability to constantly sense environmental stimuli that would not necessarily be considered a threat,” he said.
“If you were looking for an ideal and fascinating tooth to study there’s no question this would be it.”
The tusk grows in a counter-clockwise spiral so it does not curve in the same way as an elephant’s tusk but protrudes straight out.
Dr Nweeia is fascinated by the fact that narwhals put all their tooth-growing energy into a single tusk rather than having a set of teeth to help them eat their diet of large fish, such as halibut.
His previous studies of narwhal skulls and tusks held in museums revealed that the distinctive tusk is the left canine tooth that erupts through the upper lip of males.
Their right canine tooth remains embedded in their skull and in females neither of these teeth usually erupt; though in some rare cases they have a pair of tusks reaching up to 30cm long.
It remains unclear whether the animals have evolved the tusk’s sense functions or whether it is an evolutionary throw back.
“We’re just looking at one time frame in evolutionary history,” said Dr Nweeia.
“We don’t know if this is a sensory organ that is gaining more function, or is this a sensory function that is losing some of its ability?”
He added: “It’s an incomplete puzzle and basically we’ve added a few important pieces.”
The dentist suggests the sensory ability of the tusk might have advantages for males as they could use it to detect where females are, whether they are ready to mate, or how to find food for newborn calves.
His research is now focusing on traditional knowledge, asking hunters in the high Arctic for their observations in the hope that more information on the secretive animals’ behaviour can unravel the mystery of the narwhal’s tusk.
Source: www.bbc.co.uk/nature
After a two-year tour of UK art galleries, community spaces and aquariums, the Shark Trust’s acclaimed Oceanic31 exhibition takes its final bow at the Royal Geographical Society later this month. And the unique collection of artwork, depicting 31 species of oceanic sharks and rays, donated by 31 artists, is now open for bids from art lovers and shark enthusiasts. The online auction, launched today, will close on the 7th December at 8pm (BST). The money raised will support the Shark Trust Oceanics Programme.
People can now bid on 27 of the artworks by visiting this website:
https://superstars-auctions.com/sharktrustauction
It is a chance to own a beautiful piece of original art and to support the Shark Trust. The timing of the auction also means that these would make a very special Christmas gift for any shark-lover.
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- Bigeye Thresher Shark by Janina Rossiter
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- Carcharodon carcharias by Jimmy Higgs
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- Croc VR 2030 by Tom Mead
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- Oceanic Whitetip by ATM
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- Silky Street by ScapaJoe
The diversity of pieces mirrors that of the sharks and rays they represent. You can bid on paintings, digital creations, sculptures, mixed media and more. You can pick your favourite artist or species of shark. Or you can select the perfect artwork to make a statement in your home or office. Whichever you choose, you will be supporting the work to protect these amazing animals.
One of the pieces of art has been selected to be auctioned live by Steve Backshall at the For the Love of Sharks event at the Royal Geographical Society in London on the 29th November. In addition to this, two further pieces will be raffled at this event, giving people a chance to win an incredible piece of shark art. For the Love of Sharks is the Shark Trust’s flagship evening. A night to celebrate sharks. Steve Backshall is the headline speaker at this event that will see other prominent shark advocates join him on stage.
Tickets for the event can be snapped up here:
https://thesharktrust.org.uk/Event/flos24
Those that would like to see the Oceanic 31 exhibition have one final chance. It is being displayed at the Pavilion at the Royal Geographic Society from 26th November until the 7th December. Entry is free.
Find out more here:
https://www.rgs.org/events/upcoming-events/oceanic-31
Paul Cox, Shark Trust CEO, Said “This exhibition has given us the opportunity to reach out to a new audience. And inspire more people with the wonderful sharks and rays on which our Big Shark Pledge campaign is based. We are immensely grateful to the 31 artists who have worked so hard to create these works.”
Bid for your favourite Oceanic 31 artwork here:
https://superstars-auctions.com/sharktrustauction
Banner Image: Smooth Hammerhead by Alicia Hayden
Until 28 November, prizes worth a massive £10,000 – including experiences, products and tuition – feature in a line-up of items that can be won for £5 in an online prize draw to celebrate Bite-Back Shark & Marine Conservation’s 20th anniversary and help generate crucial funds for the future.
Top of the list of prizes is the chance to spend time with adventurer and wildlife expert Steve Backshall, a workout session with Nat Geo star Aldo Kane, a kayaking trip alongside white-water expert and diver Sal Montgomery and a Zoom call with ‘shark whisperer’ Cristina Zenato.
On top of that, some of the most admired companies in the diving and scuba industry have been quick to support the charity with fabulous prizes that make the £5 ticket price worth more than just a flutter.
Master Liveaboards, BSAC, Midlands Diving Chamber, Go Freediving and Blue Shark Snorkel have all generously donated experience prizes, while celebrated photographer Alex Mustard has donated a print and artists Scott Gleed and Olivier Leger have donated a sculpture and illustration to help boost the fundraising pot.
Fourth Element has donated Ocean Positive gear and LA watch company Nodus has gifted the charity a stunning dive watch. For land lovers, the charity has included a five star London hotel stay at Bankside Hotel plus a family visit to Longleat Safari Park in the roster of prizes.
Campaign director for Bite-Back, Graham Buckingham, said: “We’ve been overwhelmed with support from companies and individuals that we truly admire and who have supported us on our 20 year journey and we’re truly grateful to them all. While we feel incredibly proud of our achievements over the past two decades – and we are super excited about the next chapter – this prize draw isn’t a vanity project. It represents a real lifeline to our work and important advancements in the global protection of sharks. So we hope divers, dive clubs and even bargain hunters grab some tickets to make this a massive success.”
The charity hopes that the prize draw will generate crucial funds to launch a brand new, ground-breaking, campaign to enrol the public and increase support for the protection of sharks around the world.
To enter the competition visit www.bite-back.com/prizedraw. The prize winners will be announced on 1 December 2024.
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