Page 138 - World of Animals - Book of Sharks & Ocean Predators

Sharks & Ocean Predators
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was a critical piece because no one has really ever looked
at this aspect, as a sensory organ.” When they examined
the tusk up close, Dr Nweeia and his team found tiny
tubes, known as tubules that run from the tusk’s nerve-
rich core right through to the outer shell. These tubules are
exposed to the seawater and send signals down the tubes,
concerning the composition of the seawater, and what is
in it, to special cells at the bottom. These cells process the
information and pass it to the nerves, which then take this
data up the tusk to the narwhal’s brain.
In order to test this theory, the team travelled to the
Arctic Circle to gather data from wild narwhal subjects.
Dr Nweeia takes us through his technique for testing the
sensitivity of the tusk: “After the narwhal was brought to
shore, we would cover a half-metre section of the tusk
with the tusk jacket and attach the heart- and brain-
monitoring equipment to the whale. This was to observe
brain and heart rate activity while we stimulated the tusk
with solutions. Inside the tusk jacket, we would inject
solutions of alternating high salt and fresh water, while
monitoring the whale’s reaction.” This typically took
around 20 minutes, with minimal stress on the whale. “On

any field expedition, we would catch and release about

five to eight whales to enable sufficient samples to be
analysed,” Dr Nweeia continues.

While working in the field, the team also gathered Another shocking discovery that Dr Nweeia himself ABOVE Though no one is
traditional knowledge from the people who know the admits truly surprised him was a piece of information entirely certain of the full use
of the narwhal tusks, they also
narwhal most intimately, the Inuit of Nunavut. As the only shared by local Inuit hunters. “When you typically see feature in fi ghts between rivals
permitted hunters of the narwhal, Inuit elders have grown [narwhal tusks], they are dried out, so they’re quite rigid,”
to know the movements of these cetaceans incredibly well. he begins. “We were talking to a lot of elders and hunters
Sharing this knowledge was essential to understanding the about whales and insights were passed on to us. The
subtleties of narwhal behaviour and to dispel the myths information from them was critical. They would tell us
about these fascinating whales. that when these whales swim, this [tusk] is movable. It
For example, the Inuit were able to tell Dr Nweeia can actually flex back and forth.” Dr Nweeia says, “Quite

another interesting reason for the narwhals to visit the honestly when I looked at that, as a scientist, I thought
inlets of Hudson Bay during the summer. “Narwhals ‘I don’t think so.’” After looking into it a little further, the
come to these inlets to molt,” he says. “It has never been team found this was the case, and the narwhal’s tusk is

witnessed by scientists, since the hunters describe the a flexible organ. “I found it hard to believe!” reveals Dr
molting to be a gauze-like layer that quickly dissipates in Nweeia. “They hypothesised that a 2.7-metre (nine-foot)
the water, unlike the beluga molt that’s heavier and much section of tusk had the capability of going 0.3 metres (one
easier to observe.” A molt is when the whale sheds its foot) in any direction. Which shocked us all!”
outer layer of skin, and the fact that narwhals do this may Dr Nweeia and his team were able to prove that the
never have come to light if it weren’t for the indigenous tusk is far more than just a toothy outgrowth, and is an
Inuit people sharing their experiences with Dr Nweeia and essential sensory organ that could change the way we
the other scientists. understand narwhals and their behaviour forever.
How animals use their tusks

Elephant Walrus Hippo Babirusa pig
These tusks are actually elongated Walrus tusks are elongated Inside these gigantic jaws, the This wild boar grows two sets of
incisors, present in both males canine teeth that never stop canine tusks can grow up to tusks. The upper canines grow
and females. They’re used for growing. They can reach up to a 50 centimetres (20 inches). Not up through the skin of the snout
numerous tasks, including clearing metre (three feet) and are used famed for being the friendliest from the inside. If the tusks aren’t
paths, digging for water or roots for breaking through sea ice or animals, hippos can use their tusks ground down, they can curve

and fighting between rivals. hauling themselves onto the shore. to fight with other males. around to touch the forehead.

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