Over 60% of our planet is covered by water more than a mile deep. The deep sea is the largest habitat on earth and is largely unexplored. More people have traveled into space than have traveled to the deep ocean realm…. – The Blue Planet: Seas of Life (BBC)
Most of the life that we know about in the world’s oceans lives in the light zone of the intertidal and epipelagic zones (basically, coastal waters and the light zone of open water). The life that exists there is largely as a result of the amount of sunlight available for photosynthesis. What is little appreciated, however, is that this is only the smallest fraction of our oceans. The rest is deep, dark and very very cold. Photosynthesis doesn’t occur past 200 metres and sunlight is absent altogether below 1000 metres.
Sounds deep, doesn’t it? Let’s put that into perspective. The deepest part of the ocean is the Mariana Trench, in the western Pacific Ocean. A very long, but narrow trench, it has been charted as deep as 10.91 kilometres (6.78 miles) at one specific spot (the Challenger Deep, a small slot-shaped valley in the floor of the Trench), but there may be deeper spots (and some measurements have even charted it as being as deep as 11.03 kilometres (6.85 miles).
Or perhaps 11.03 kilometres doesn’t sound too deep to you. I mean, considering that my best time, without crazy training, for running 10 kilometres hovers around the 42-minute mark, that could be covered pretty quickly. So, let’s give that a little perspective. Say, for instance, that you were to place Mount Everest on the floor of the Trench, there would still be over 2 kilometres of water above it. Not. Too. Shabby.
So when it is so deep and so dark, what could possibly live down there? That’s what is so cool … we continue to discover new wonders in ocean systems every year in places that we have barely scratched the surface of (or the bottom, I guess).
How do we know what is down there? We’ve known since the 60’s actually. January 23, 1960 to be precise, when the U.S. Navy sent a manned submersible into the depths of the Mariana Trench. As the Swiss-designed, Italian-built and U.S.-operated bathyscaphe Trieste reached the bottom, its occupants, Lieutenant Don Walsh and Jacques Piccard, observed a colourless sole or flounder-like creature, as well as an unidentified type of shrimp. At the world’s deepest known spot.
Funnily enough, James Cameron, director of The Abyss, Terminator, Avatar and The Titanic recently announced that he will be doing a solo manned submersible dive to the bottom of the Mariana Trench this year!
Since the 60’s we’ve started to explore more of the world’s deepest spots, but we’ve covered less than 5%. One of the more recent studies has been observing vents in deep waters. One of the forms of seafloor vents are “black smokers”. They’re called that because they gush smoky looking black liquid into the surrounding waters at temperatures thought to exceed 450 degrees Celsius. That’s hot. Hot enough to melt lead. And when I say “seafloor”, we are talking 5 kilometres down. Yet at the bottom of a dark and in this case, very hot, ocean trench, living in and around these ridiculously toxic and scalding vents are yet another species of blind pale shrimp (we recently posted a facebook link of these critters, but if you want to read more about them, you can follow this link: http://www.bbc.co.uk/news/science-environment-16493787). These shrimp have an organ on their back that, scientists believe, is the way that the shrimp navigate around without getting toasted.
And they’re not the only critters down there in that hell at the bottom of the ocean. In fact, a few years ago, the Yeti crab was also discovered living in and around similar hydrothermal vents.
Rather than avoiding the toxins, for the yeti crab, the filamentous bacteria on its pincers detoxify poisonous minerals in the vents.
No light. Immense cold. Sometimes incredible heat. And yet life flourishes.
That lack of light at these depths has also resulted in some phenomenally colourful marine life. Certain deep-sea creatures take advantage of that lack of light, to distract prey, to act as lures, as camouflage (such as the Hatchet Fish), to mimic other poisonous or dangerous creatures, to intimate that the creature is not to be messed with, in mating rituals and for reasons we have yet to determine.
As you can see, the bioluminescent colours commonly found are blue or blue-green. As the colour spectrum changes with depth (red being one of the first colours to disappear as we get deeper), blue and green can still be seen at depths where there is no light. Despite this, some creatures also rely on red, such as the Deep-sea Dragonfish. This critter lives in deep waters in the Atlantic and the Gulf of Mexico at depths of approximately 1500 metres (5000 feet). Why red when it is almost invisible to most deep-sea dwellers? It is thought that the Dragonfish uses its red photophores to “paint” targets when it hunts.
Outside of strange-looking creatures that use bioluminescence, there are also just strange-looking creatures! Some that resemble little more than gelatinous masses, or are oddly-shaped cousins of shallower dwellers,
(Courtesy: The Telegraph, Kaboodle, National Geographic, PLoS Biology Journal)
And that last octopus … wasn’t only found deep (about 2000m), but also at the bottom of cold cold Antartic waters!
We’ve even been privileged to find some new fantastic discoveries close to home (Canada that is) during a recent expedition to the waters the Flemish Cap: http://hudson0292010.blogspot.com/2010/ and https://sites.google.com/site/hudson0292010/documents
The point of all this blog? Well, it’s that we’ve only just begun to explore the weird and the wonderful world of the deep. And hopefully, we still have time to do so. That is, before our destructive nature makes its way into the deepest darkest depths as well.
A more eloquent and well-produced encapsulation of what I’ve tried to focus on in this blog is captured in this fantastic little presentation: http://www.youtube.com/watch?v=Uqly8ERIkHM
…..submarines scare the bejesus out of me, but wouldn’t it be cool to go down to the bottom of the greatest depths and see the life flourishing there?