Most species of shark evolved in the oceans before the first trees evolved on earth.
They’ve been around up to 450 million years and have survived 4 mass extinctions so far.Many
of the OG ancient sharks that first started to appear millions of years ago remain virtually
unchanged today, like this frilled shark--yeah, that guy’s been through some stuff.
One thing's for sure, you probably wouldn’t want to be caught swimming near a shark, let
alone a Great White.
Yet that’s what long distance swimmer Ben Lecomte could encounter as he journeys across
the Pacific Ocean from Japan to San Francisco to raise awareness about Ocean health.
Seeker will be tracking Ben and bringing you updates on the crew’s efforts to collect
the most extensive data set on the Pacific Ocean to date, so make sure you check that
out.
Oh and to be clear, as Ben draws nearer to San Francisco he will be crossing expanses
of water that are known Great White migration areas...yikes!
Great Whites are a species of shark that recently been discovered to live longer than previously
thought, to around 70 years or more.
However, some sharks can live to be really old AF--in some cases even living centuries
longer than we’d thought before, giving us new insight into both shark ecology...and
potentially the science of aging.
Ok let’s back up.
Scientists have thought that sharks were probably older than originally estimated for about
a decade.
And I’m talking individual sharks, not sharks as a group of animals.
But results from a study published in 2017 used novel methods to definitively determine
that yes, sharks live really unexpectedly long lives.
Most biologists age fish by measuring features like scales and otoliths, which are boney
calcium deposits that are essentially a fish’s ‘ear bones’.
Measuring these is like measuring tree rings and can help us track seasonal growth and
organism age.
The problem is, sharks lack many of these key structures.
They don’t have scales the same way other fish do, and they don’t have otoliths.
Instead, shark scientists have been making do by counting the calcified growth bands
that form along a shark’s cartilaginous spine--but this isn’t necessarily that accurate,
and the older the shark, the harder it is to calculate its age this way.
This new study took a different approach, looking at bomb carbon dating age data.Bomb
carbon dating is based on the atmospheric nuclear tests that were conducted in the 50s
and 60s, which deposited a huge spike of radiocarbon into the atmosphere.
We can detect the spike of this particular radioisotope in the tissue of animals that
were alive during those tests.
This most recent study I mentioned compared bomb carbon dating with the previous age estimates
found by measuring just the growth bands, and found that the growth band estimations
of shark age could be off by more than half.
This breakthrough is important, not because we’re obsessed with being rude and asking
sharks how old they are, but because conservation policy is built around organismal life spans.
Greenland sharks, for example, are a near-threatened species of shark that claim the title of longest
living vertebrate on Earth--they could live up to 500 years, and this means that they
don’t even start to reproduce until they’re almost 150 years old.
Fishing regulations and environmental protections that impact shark populations of all kinds
are built on population models that rely on our knowledge of how these animals survive
and reproduce, and if our numbers are wrong, it could spell disaster for conservation efforts.
Ever since the extreme life-span of the Greenland shark was uncovered, scientists have also
been interested to see what they and their fellow long-lived counterparts could teach
us about living for centuries.
These organisms, despite being literally as old as the Enlightenment in some cases, still
seem to have low incidence of cancer and other age-related diseases.
One possible explanation for this is that they spend their lives thousands of meters
below the surface in freezing temperatures, which slows down their maturation and metabolisms.
But this is still a matter of scientific investigation, and it remains to be seen if anything of use
will come of studying ye olde shark health.
For now, we can use our improved understanding of their life cycles to inform our conservation
efforts in the face of overfishing and changing oceans during climate change.
And as for me, there’s no way I would endure those living conditions, even for near immortal
life.
So, do you think you got what it takes to swim across the Pacific ocean?
Even now knowing some sharks have been lurking there for centuries?
Check out how Ben Lecomte prepared for his trip and how they’re collecting the most
extensive data set during his journey.
And fun fact, female sharks can use sperm from multiple males, meaning some pups born
at the same time are actually half-siblings.
Sharks, guys!
They’re so cool.
I’m maren thanks for watching.