An unseen world

As a crucial source of food to many aquatic organisms, plankton plays an important role in balancing ocean health and the food web. Despite their significance, these miniscule critters are rarely seen up-close.

Words & photographs by Jan van Ijken

Since plankton caught my attention a few years ago, I have been fascinated by these minute creatures. Their variation in bizarre shapes, vibrant colours and delicate structures is endless. And because they are often transparent, you can see their inner organelles and body parts in function. The types of plankton are extremely numerous; in certain blooms, they are even visible from space. Yet only a few people are aware of their immense beauty because the creatures are invisible to the naked eye. Only through a microscope can they be observed. 

For me, the exquisite beauty and importance of these little-known creatures was reason enough to start a photo and film project uncovering this unseen microcosm. It would take me more than three years to finish the project now called Planktonium, but the basic idea behind the film and photo series was to show the plankton as living organisms in all their splendid beauty, colours and fine details. 

To collect the plankton, I went out into nature equipped with a basic plankton net with a mesh width of 30mu (1 mu/micron is equivalent to 0.001mm). An attached rope allowed me to throw it out in the water. I decided to take samples in different types of water in The Netherlands, including small freshwater ponds in the dunes, forest lakes, the marine environment of the North Sea as well as the brackish Grevelingenmeer, a large saltwater lake. Surprisingly often, I found unexpected and interesting species in the most obscure and overlooked small ponds. Every water seemed to have its own biotope in which the organisms have adapted perfectly to their environment. Sometimes animals like the rotifer, also called wheel animalcule, adopt the colour of their surroundings. These microscopic aquatic invertebrates would, for example, turn brown in a forest pond setting. 

My organism catches were diverse, and I was constantly surprised by my findings. I caught plenty of wonderful diatoms (types of phytoplankton), eggs and larvae of sea creatures floating in the plankton in the North Sea. One of the most intriguing species of diatoms I found were the Bacillaria paxillifer, also called carpenter’s rule diatom. These colonial, motile diatoms form the most wonderful and bizarre shapes while being attached to their neighbours. In the brackish waters of the Dutch province of Zeeland, I found the most beautiful colonial diatoms (Licomphora flabellata) as well as tube-dwelling diatoms. I also travelled to many remote freshwater ponds, puddles and lakes where I found very different species of water fleas, rotifers and copepods. The latter sometimes had peritriches or diatoms attached. Further species I found included ostracods, testate amoebae, desmids as well as water mites. One of my main observations during the sample collection: the colours and body structures of the species varied significantly between different waters. 

Some plankton species are capable of incredible things. As an example, certain water fleas can give virgin birth by parthenogenesis. Some species of rotifers can shrink themselves to form a very tiny cyst in which they can survive dozens of years of drought before they revive again when conditions are favourable. My film Planktonium depicts a scene of the water flea Polyphemus pediculus giving birth to live offspring. It still astonishes me that a creature this small – it is invisible to the naked eye, so I enlarged it 100 to 200 times – can be pregnant with multiple developing embryos and is able to give birth to live offspring.

But plankton is not only interesting and beautiful to watch, it also does even bigger and more impressive things: Some organisms have been around for millions of years and have invented the oxygen, thus often referred to as the source of all life. Furthermore, ancient organisms such as cyanobacteria can still be found in unchanged form in out waters today. While the term ‘plankton’ is derived from the Greek word of ‘planktos’, meaning wandering or drifting, any living creature floating in the ocean or in bodies of freshwater is classified as plankton. Plankton can vary in size, it can come in the form of small bacteria or take the shape of very long siphonophores, it can describe free floating eggs as well as embryos and larvae of various marine animals such as molluscs and fish.

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Issue 23
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This feature appears in ISSUE 23: High Seas of Oceanographic Magazine

Issue 23
Supported by WEBSITE_sponsorlogos_blancpain
Supported by WEBSITE_sponsorlogos_blancpain

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