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The otherworldly creatures in the ocean's deepest depths - Lidia Lins
The otherworldly creatures in the ocean's deepest depths - Lidia Lins
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0:07
It's easy to forget how vast and deep the ocean really is.
0:11
About 60% of it is actually a cold and dark region
0:15
known as the deep ocean.
0:18
And it reaches down to 11,000 meters.
0:21
Yet, this remote zone is also one of the greatest habitats on Earth,
0:26
harboring a huge diversity of life,
0:28
from giant squids and goblin sharks
0:31
to minuscule animals smaller than a millimeter.
0:35
How do so many species thrive in this underwater world?
0:40
Over the decades, intrepid scientists have ventured there to find out.
0:44
Traveling down through the water column,
0:46
pressure increases and light begins to wane.
0:50
At 200 meters, photosynthesis stops
0:54
and temperature decreases from surface temperatures
0:57
by up to 20 degrees Celsius.
0:59
By 1000 meters, normal sunlight has disappeared altogether.
1:04
Without light, life as we know it seems impossible.
1:08
That's why in 1844, the naturalist Edward Forbes
1:12
wrote his Azoic Theory,
1:15
Azoic, meaning without animals.
1:18
Forbes was sure that nothing could survive below 600 meters
1:23
on account of the lack of light.
1:25
Of course, the discovery of deep-sea species proved him wrong.
1:30
What Forbes failed to take into account is something called marine snow,
1:34
which sounds much nicer than it is.
1:37
Marine snow is basically organic matter,
1:39
things like particles of dead algae, plants, and animals,
1:43
drifting down into the depths
1:46
and acting as food for deep-sea animals.
1:49
Largely thanks to that, abundant life forms exist in the darkness,
1:53
adapting to a harsh reality where only the weird and wonderful can survive.
1:59
Fish with cavernous mouths,
2:00
spiky teeth jutting from their jaws,
2:03
and lamp-like structures protruding from their heads,
2:07
like the anglerfish which entices prey with its misleading glow.
2:12
Several sea creatures have perfected this lightning technique
2:15
known as bioluminescence,
2:18
using it to lure prey,
2:19
distract predators,
2:21
or attract mates.
2:23
Some creatures use it for camoflauge.
2:25
In parts of the water column where only faint blue light filters through,
2:29
animals bioluminesce to match the glow.
2:33
Predators or prey looking up from below
2:36
are deceived by this camoflauge,
2:38
unable to see the creatures silhouette.
2:41
Such otherworldly adaptations also arise from the need to locate
2:45
and snatch up food before it drifts away.
2:48
Some sea animals, like jellyfish, comb jellies and salps
2:53
can migrate between depths
2:55
partially because their 90% water consistency
2:58
allows them to withstand immense pressure.
3:01
But they're the exception.
3:03
Most deep-sea creatures are confined to a narrow range in the water column
3:07
where nutrients are scarce
3:09
since the food drifting downwards from the surface
3:11
rapidly sinks to the sea floor.
3:14
Plunging all the way down, we find more exotic creatures.
3:18
Some take on dwarfism,
3:20
a trait that transforms them into miniature versions of animals
3:24
we see closer to the surface.
3:26
It's thought that reduced food availability causes the shrinkage.
3:30
Only a tiny fraction of the food produced at the surface reaches the sea floor,
3:36
so being small gives animals a low energy requirement
3:39
and an adaptive advantage.
3:42
And yet, the sea is also the land of giants.
3:45
Here, gargantuan squids can reach 18 meters long.
3:50
Isopods scuttle around the sea floor like enormous wood lice.
3:54
There are long-limbed Japanese spider crabs,
3:57
and oarfish, whose bodies stretch to 15 meters.
4:01
This trait is known as gigantism, and it's something of a mystery.
4:06
It's thought that high oxygen levels may drive extreme growth in some species,
4:11
while the colder temperatures promote longer life spans,
4:14
giving animals the opportunity to grow massive.
4:17
Many of these exotic sea beasts will never experience sunlight.
4:21
Some will venture up through the water column to feed,
4:24
and a few will actually break the waves,
4:27
reminding us at the surface
4:28
about the incredible survival skills of the ocean's deepest inhabitants.
4:33
Humans still have an astounding 95% of the ocean left to explore.
4:38
So those depths remain a great mystery.
4:41
What other untold wonders lie far below, and which ones will we discover next?
