Guest essay by Mike Jonas
The UK’s public broadcaster, the BBC, reported on 7 December 2017 that:
Narwhal escape: Whales freeze and flee when frightened
Scientists who fitted heart rate-monitoring tags to Arctic narwhals have discovered a strange paradox in how the animals respond to threats.
When these tusked whales are frightened, their hearts slow, but at the same time they swim quickly to escape.
Scientists say the response could be “highly costly” – because they exert themselves with a limited blood supply.
They raise questions about how the enigmatic “unicorns of the sea” will cope with increasing human intrusion on their Arctic habitat.
Historically, narwhals have not come into contact with much human disturbance, because they live mainly hidden among Arctic sea ice. But in recent decades, as the ice has declined, this is changing.
“Shipping and exploration for oil and gas is moving into the narwhals’ world,” said lead researcher Dr Terrie Williams, from the University of California, Santa Cruz.
The article continues, but its basic message is clear: evil oil exploration and human interference will give narwhals heart failure.
As so often happens with BBC articles, especially those that report on things in the journal science, it immediately triggered my BS indicator. How can Narwhals have survived for millions of years if they react this way to stress? For example, if a pod of orcas comes past would a narwhal just die?
A quick search led me to Cool Antarctica [that might be the wrong end of the planet, but I wasn’t going to spend a lot of time on this]:
Narwhal – Facts and Adaptations – Monodon monoceros
Diving physiology (physiological and anatomical) – Whales and seals have a number of adaptations that allow them to dive deep beneath the sea for extended time periods, narwhals can dive to 1,500m (4,900 feet) and stay submerged for up to 25 minutes.
· The lungs are collapsed lungs on diving with only the minimum of air held in the respiratory system. This prevents any retained air (or more specifically the nitrogen in that air) from being forced into the blood under pressure at depth and coming out again on resurfacing so resulting in the “bends” which can be damaging or even fatal.
· Bradycardia, the slowing down of the heart considerably from the normal rate. Blood is directed only towards the vital organs such as the brain and heart and to the swimming muscles and those associated with catching prey. The rest of the body is largely bypassed for the duration of the dive to retain oxygen for immediately necessary purposes only.
· Large amounts of myoglobin in the swimming muscles to store oxygen for use during a dive. Myoglobin is a large protein molecule similar to haemoglobin that carries oxygen in the blood. Haemoglobin gives up its oxygen before myoglobin does, so once the haemoglobin source of oxygen is exhausted, then myoglobin gives up its oxygen to the muscles enabling them to work efficiently for longer. large amounts of myoglobin in diving animals makes their muscle a deep red colour.
· Oxygen loading and ridding of carbon dioxide before a deep and long dive. Long deep breaths are taken while at rest before diving to clear dissolved CO2 from the blood and load up haemoglobin and myoglobin with oxygen before the dive to enable a longer period before the next breath.
The first thing that springs out is that the behaviour which the BBC reported with “Scientists … have discovered …” was already well-known.
The second thing is that this physiological behaviour is brilliant for narwhals’ survival.
I didn’t need a third thing. If a narwhal comes across a human – even an evil oil driller – the narwhal will do just fine.
Footnote. I know absolutely nothing about narwhals. I’m simply someone that likes to check stuff before accepting it. I freely acknowledge that I might have completely misunderstood everything, in which case I would be very grateful for any correction. I’m always happy to be proved wrong – it’s a lot better than remaining wrong.