PLANKTON

The topic of this column is based on the opening ceremony of Rio 2016 Olympic Games. Though it was a cut price performance because of economic depression, at less than half the cost of London Olympics 2012 (£9.3bn), it was glitzy and sexy with super model Gisele strutting catwalk along the length of Maracana stadium, followed by Samba dancers in hip grinding carnival style.

The theme was basic, depicting the rich history of multinational Brazil with a special homage made to the Amazonian Rainforest that evolved from single celled organisms, 3.8 billion years ago. Rainforests are so called because they are dense jungles with tall broad leafed trees and very heavy rain each year. Amazon Rainforest in Brazil is the biggest with a variety of animals and plants sustaining the life of many indigenous peoples. The climate in the Rainforest is warm and humid.

As shown in the beginning of the ceremony, Rainforests are world’s oldest ‘ecosystems’ ie the oldest community of living creatures (animals and plants) and their environment that has evolved from organic single cells without nuclei (bacteria eg Tetanus bacteria), which were formed from inorganic matter – the “Primordial Soup” (cf. Author, Points to Ponder, The Origin of Life, 2013: 273-276).

When I was an undergraduate in Biology, there was a vague hypothesis of the of the origin of life   that came from inorganic matter; and most biologists believed in God’s creation though they were teaching evolution. Microscopic ‘organisms’ such as amoeba were as far as we went for the beginning of evolution. Now they have found evidence God had no part in “creation”. Organism are molecules with carbon. All living things contain carbon.

Scientists have ignored the impropriety of the Biblical Genesis. According to Genesis, trees were created on the third day of the Creation Week. This means they are discontinuous with other plant forms eg cabbage or aubergine. Naturalists posit that trees arose by ‘random process’ ie by natural selection due to adaptation to the environment from simpler photosynthetic organisms. In substantiation, they have found fossil evidence for tree evolution from putative non-tree single celled ancestors. When complex biochemical systems were analysed within a Biblical worldview, the data are inconsistent with the Genesis account that God directly created trees.

For this article, in relation to the Amazon Forest, it is the vegetable “plankton” known as phytoplankton that I want to deal with. They are microscopic single celled organisms . They are of three types: (1) Diatoms – algae with transparent silica cell walls that live in oceans and fresh water; (2) blue-green algae or cyanobacteria that live in oceans and fresh water; and (3)Bacteriaplankton – bacteria and archaea (rapidly moving type of bacteria), which absorb nutrients dissolved in water. Cyanobacteria are unique in that they photosynthesise like trees. They can be found near the surface of the ocean all over the world. They are the ancestors of trees as in the Amazon Rainforest.

Phytoplankton also form the base for food chain for life on earth. They use sun’s energy and carbon dioxide to make sugar (photosynthesis), which in turn provides a rich supply of food for zooplankton and other creatures that eat them. These zooplankton by turn, are eaten by larger zooplankton, fish and whales. Little fish are eaten by birds and bigger fish, which again, are eaten by others, and so forth. All animals thus, depend on plankton for survival.

What’s plankton? Plankton (single -plankter) are single celled microscopic organisms that drift in the sea or fresh water currents, and eggs and larvae of larger animals. They cannot swim. They now include jellyfish, and siphonophores, the longest animal in the world, which are very thin, jellylike and very fragile. Jellyfish were never plankton during my college time. They drift in the ocean and have also some swimming ability. A German scientist named Victor Hensen gave plankton this name from the Greek word ‘planktos’ – drifters.

Plankton are of two types: (1) animal plankton or zooplankton; and (2) plant plankton or phytoplankton. Plankton are massive and can be found in any body of water that covers 71% of the Earth. You can find thousands of plankton in a drop of water, accounting for 98 percent of oceans’ biomass (the total quantity of organisms in a given area or volume of water).

Phytoplankton, such as Cyanobacteria are photosynthetic bacteria [bacteria are the simplest single-celled organisms; they are neither plant nor animal. I used to be quite confused in school and college with what is bacteria or germ – believed then to be creepy-crawly bugs, as nobody could explain]. They are unique as they can manufacture their own food. They are quite small and usually rounded, they can link to each other and grow as algae in colonies large enough to see (Kung in Manipuri). They are the oldest known fossils found, more than 3 billion years old. They are still around and have been tremendously important in shaping the evolution and ecological change throughout the Earth’s history. Without the oxygen they generated, there could not have been life or human beings on earth.

Cyanobacteria are precursors of plants. The first land plant originated from these unicellular blue-green algae. The evolution of multicellular organisms coincided with an increase in the diversification of cyanobacteria, ranging from unicellular to multicellular filamentous forms, and the Great Oxidation Event (GOE) – when they raised the oxygen levels in the atmosphere around 2.45–2.32 billion years ago. Scientists are working to reconstruct events in the evolution of oxygenic photosynthesis on the scale of entire genomes, taking the opportunity of the rapid advances in published genomic sequences of cyanobacteria.

Our Earth’s first modern tree (Archaeopteryx – an extinct tree) establishing itself in developing forests including Rainforests across the Earth’s surface, emerged around 370 million years ago (Mya). Ancient trees made it out of water 130 million years earlier, but none were considered “true” trees. They had fernlike foliage, secondary xylem (water transporting system from roots to the leaves). But they were a major vegetative component of the Devonian period (geographical era when major animal groups colonised the land,416-358 million years ago (Mya).

Another tree in this group – Wattieza – is thought to be the earliest tree that arose in the later Devonian 380–360 Mya). In the 1870s, an intact crown was discovered in New York, and its reconstruction suggests that it was at least 8m tall, fern-like, with a trunk bearing long branches and having a root system with complex vascular tissue.

Trees are of two varieties (1) vascular- those that have a system of bringing water and nutrients from the roots to the leaves, and (2) non-vascular – those that have no such system such as the mosses and the liverworts. They are thus very short. It’s not known if non-vascular plants evolved from the multicellular green-algae and gave rise to primitive vascular plants. Scientists are working to reconstruct events in the evolution of oxygenic photosynthesis on the scale of entire genomic sequences of cyanobacteria.

Zooplankton can live near the surface or deep in water. Most of them are single celled organisms but there are bigger sizes such as famously, krill (shrimp-like with 82 species, which is main dinner for blue whales, largest marine animals. They differ in size from 5mm to 50mm. A blue whale will consume 40 million of krill per day by ‘filter feeding’ ie they swim with its mouth wide open towards the current with superswarms of krill that contain trillions, drifting with the current. Then it will retain the krill behind bristles like a comb and pump out the water. It’s marvellous to see them live in action in the National Geographic channel.

Jellyfish (5 to 25 cm across) is interesting. It is shaped like an umbrella and looks like clear jelly with frills (tentacles – 24) around the edges. (I vaguely remember a small one about 5-6 cm long – preserved one, for teaching purposes in my undergraduate class). It has no brain or eye but a simple nervous system that reacts to touch stimuli. The tentacles have stinging cells that paralyse potential prey when they come in contact with them. It’s really like a big stomach. It takes food through a hole (mouth) and expels waste through the same hole. It can perceive light and floats in warm water, drifting with currents, sometimes towards beaches, causing danger to holidaymakers.

Modern research has found more than a million species of plankton by a team of marine scientists, during a 70,000-mile voyage around the world’s oceans, lasting more than two years aimed at learning more about the effects of climate change. In July 2015, a single celled microscopic marine plankton that has evolved a miniature version of an eye that can help it to see its prey has been found. It’s a dark purple spot known as ‘ocelloid’ that resembles the multicellular eye found in humans and large animals.

Evolution explains with supporting evidence, the origin of life on Earth. Phytoplankton still account for as much oxygen as all the rainforests and land plants combined, and absorb a third of planet’s carbon dioxide in the process, helping to control global warming, and lending a hand to  aquatic and land animals, including human beings to breathe safely.