Imagine a dive in the open ocean: you put on a mask, slide off the boat, dip your head into the water and look down at the dancing light rays piercing the strata for dozens of meters and disappearing into the darkness. A couple of deep breaths, a couple of confident fin strokes, and you discover yourself in a different world. Silent but full of sound, motionless but capable of taking you for thousands of kilometers. You see the color of that space, feel its weight and density, sense it with your skin. These few minutes in another world change your natural perception of reality through a unique combination of sensory signals that only exist here, underwater, a few meters below the surface. Sometimes it's such a powerful emotional experience that you allow it to overwhelm yourself, being open and freeing your head from external thoughts. It's a fantastic feeling to merge with the ocean, controlled teleportation of consciousness. Or you're at work, paddling with a massive camera against the current in murky water, wearing a heavy dry suit, and sweating like hell. Unaware of the subzero water temperature and vigorously filling the silent world with sounds because you haven't seen a single sea angel for 40 minutes, which is the only specific critter you need to film. That happens, too. But light rays are always lovely. Rays mean it's bright, shallow, and definitely not an icy ceiling overhead.
So. For countless ocean creatures, the open water has been their only reality for millions of years. The entire range of physical factors of the underwater environment, such as temperature, pressure, salinity, and adsorption of different parts of the sunlight spectrum - all determine their evolutionary path and their whole life in the present: from anatomy and adaptive coloration features to tricky strategies of hunting or breeding. While we teleport between worlds and philosophize during freediving with our sophisticated brains and technologically advanced carbon flippers, these guys live their little lives right next to us, making it possible for us and the rest of the planet to exist.
All sorts of things inhabit the water column: from giant 30-meter blue whales and sailfish that can reach 110 km/h to deep-sea Deepstaria jellyfish that resembles an alien blanket or bizarre Vampire squid from hell (that's the actual scientific name!) and tiny Sapphirina copepod crustacean that sparkle brighter than diamonds in the sun. It's a magnificent universe of unearthly diversity whose core is plankton. Everyone knows the word, but many do not understand its precise meaning. Plankton is the combined entity of all organisms living in the water column that cannot resist currents. Therefore, the tides, waves and wind, upwelling and descending currents carry not only a vast mass of water but also all the plankton they pick up. The creatures that can actively move against the current are called nekton. These are most fish, sea snakes, turtles, cetaceans, pinnipeds, penguins, and other aquatic guys. And then there's the benthos, the seafloor population. But we are talking about plankton today.
Their home, The World Ocean, occupies most of the planet: 71% of the surface, 3.68 kilometers average depth, and a total volume of 1.35 billion cubic kilometers. That's so much more than I can handle in my imagination. It is possible to assume that most inhabitants of the water column, especially the smaller ones, will never encounter a single wall or a solid surface in their lives. They exist in the borderless realm of open water. That is why, evolutionarily, many have no arms, legs, or suction cups - not a single tool for dealing with the "hard" world. Moreover, many of these creatures are delicate gelatinous animals, only able to survive in open water, and can be destroyed by even a slight touch.
There is an incredible amount of plankton. So much that I have to go look up what the enormous numbers of that order are called. According to some estimates, there are more phytoplankton - tiny photosynthetic algae and cyanobacteria - in the world's oceans than stars in the known universe. "A billion billion billions," says a popular science article from the Massachusetts Institute of Technology. What is that number anyway? The heck knows, but it's significant in any case. Its significance is that these little things produce more than half of all oxygen on our planet, withdraw a tremendous amount of CO2 from the atmosphere, and in addition, serve as food and the foundation of the entire food chain, which involves the whole population of the ocean and surrounding areas, including us, human beings. Closing a thread with numbers, it is worth pointing out that about 3 billion people on the planet are critically dependent on the gifts of the sea. If we take phytoplankton out of the system, the world will face catastrophic starvation, or it won't because everyone will suffocate before that. By the way, this is one of the pessimistic predictions for 2100: a 6-degree increase in average ocean temperature will disrupt the process of photosynthesis, leading to a cascading collapse of the atmosphere and then of everything and everyone else. I don't trust these models, but the pessimists are worth listening to.
Plankton's contribution to the climate and all life on the planet is one of the many reasons it is essential to study. One of many global reasons, but there are hundreds and thousands of local ones, such as the development of drug-delivering nano-robots that move through blood vessels with the biomechanics of a jellyfish dome. Or the construction of nuclear power plants, which requires considering the life cycles of various invertebrates when organizing water cooling, to avoid a situation like in Scotland (Sweden, Israel, Japan) - jellyfish consistently screw up power plants all over the world 2-3 times a year. The extraordinary world of plankton is something not only scientists should study and keep in mind but also atomic plumbers, industrial fishermen, shipbuilders, seafarers, and even the military. And artists, of course - it's a whole ocean of inspiration! All these weird forms of life that inhabited different ocean domains over millions of years of evolution can never be designed from scratch.
The ephemeral beauty of plankton is, to a certain extent, a snag for its study. It is not easy to learn all the nuances of the life of creatures, transforming into a shapeless ball of snot from a single careless push. Others cannot be seen in daylight because their bodies are perfectly transparent and furthermore covered with tricky nanostructures that absorb light and prevent it from being reflected, further hiding the animal from prying eyes. Others do not fit into any container or aquarium since their size of several tens of meters is not feasible for laboratory studies. All these invertebrates cannot be strapped with little rucksacks, trackers, and tiny cameras to follow what they are doing there in the depths of the ocean. They can only be observed underwater - with our own eyes or with astronomically expensive robots with massive camera lenses instead of eyes. We cannot even dive deep into the evolutionary history of plankton. These gelatinous invertebrate beings do not leave proper imprints in eternity, and we have to guess about many things from scrappy data with gaps of that size (showing the gaps spreading my hands).
Despite all the difficulties, we have already discovered and understood a lot. Scientists are stubborn and enthusiastic people, and this combination always yields results: plankton, even the gentlest, can be caught with a robo-arm with a bucket and carefully delivered to the caring man-hands of researchers; plankton nets go down kilometers deep and come back full of living treasures; cameras with the light sensitivity of two million ISO film spectacular videos of bioluminescent animals in extreme darkness. Some particularly skillful guys maintain cultures of planktonic organisms in laboratory aquariums and study every aspect of life that can be examined in aquariums. Other die-hards (oh, hi!) spend hundreds of hours in the night sea, under the ice, and in other awkward places observing animals up close in their homelands, while others monitor jellyfish from satellites with a mug of hot tea. So, piece by piece, over tens and hundreds of years of research, we are progressively putting together a giant picture with holes - a colossal puzzle with many things still missing. Still, it is already clear that it is all fascinating, beautifully composed, and interconnected. We can already point our fingers at its various sections and confidently explain what it is and how it works in the whole system. We can only generate theories and speculate at the edges of the gaps, and for the empty areas - well, that's intriguing!
Of course, the piece-by-piece puzzle is a two-dimensional simplification. The ocean is immense and multi-layered; it is an alive and dynamic environment of unimaginable volume, with invisible connections between all the elements of the system we have yet to find and understand. It's a work in progress for several generations of explorers, who will become more diligent as technological advances make exploring the depths far more exciting and efficient year by year. As a big fan and proactive user of underwater photo and video technology, I explore the ocean through camera lenses, and plankton is my favorite thing to study. It is also by far the most beautiful. Jellyfish of all kinds, three-meter-long ctenophores, pteropods, siphonophores, salps, polychaetes, and countless larvae of fancy shapes, oh my. I will cover all of these lovely beasts in great detail in the following articles. So much more to see ahead :)
Stay tuned!
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Few more pictures:
Now we're done!
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Lovely article. I had never imagined there might be more phyto plankton than stars in the known universe.