SYMBIOSIS: A beneficial arrangement between two organisms.
Symbiotic relationships occur mainly in three forms:
1. Mutualistic: where both parties benefit from this relationship . Possibly the best known example is Bees and Flowers. Bees pollinate flowers and plants set fruit. In return, Bees take some pollen home and make yummy honey. Everyone is a winner!
2. Commensalistic: where only one party benefits but does not help or harm the other. Remora fish are the ones we see in documentaries that attach themselves via a suction disc on their heads to whales and sharks. They benefit by getting a ride and food (downstream of Gills), while the massive whale or shark do not care and are definitely not harmed.
3. Parasitic: where one party gains while the other party suffers. This example has been the scourge of especially tropical parts of the World forever. The Malaria mosquito – survives and thrives through it’s human Vampire desires, causing severe illness sometimes leading to death in humans.
Bats, Moths, humans and street lights make up this tale of urban Symbiotic relationships.
Across the street from where I sit, Streetlights have just switched themselves on due to Modern Solar technology. Red Taxi is parked almost under one. It is dusk in Kuala Lumpur at about 7.05pm. Just behind these streetlights a City Centre Remnant local Forest strip is doing its bit as a Carbon Sink sucking in Carbon gas and pumping out Oxygen as part of its established ‘bag of tricks’. It is about twenty metres wide and 150 metres long, rises steeply from the footpath to a now vacant private property that has established tree cover behind. 95% of the tree canopy is probably only 30-50 years old while one original remnant 250 years old ++ Tree stands tall above all. (left hand side of photo below). Small trees, many shrubs and ground-covers form an impenetrable understory to us humans but a perfect sanctuary for others.
The strip is home to many local Monkeys, Civet Cats, Squirrels, the odd feral Cat, street Dogs, Crickets, Lizards, Bugs, Microbes, Bats, Moths, Butterflies, many Birds and maybe the odd Snake or two or three. A simple Biodiversity assessment would rate medium to good, maybe higher as it does comfortably support many organisms. This healthy ecosystem is quietly going about its own business in the middle of Town, while the most modern PNB 118 Tower pumps its way upwards at the rear.
This dense canopied and leafy urban forest is perfect habitat for Bats to make home, safe from predators and light glare, night and day. So many layers of plants provide a Nursery for Moths to lay eggs on and under many leaves, pupate to munching Caterpillar and metamorphose to a glorious Moth. Plenty of room for Bat and Moth alike. As far as Moths are concerned the leaves exist solely for their survival pleasure. (Is that parasitic symbiosis? One severely maims and kills the other – Caterpillar devouring leaf sometimes rapidly, definitely fits that Criteria. PS: Plants have feelings too, you know! They feel the pain of violent chomping! Extremely Parasitic!)
Is the Moth mindful of the larger and blacker flying inhabitants of this inner urban skinny forest? Doubtful, as sufficient grey matter has never been the Moth’s strong point. Are the Bats aware of their smaller fluttery neighbours? Certainly are.
Fading dayglow is done. Night is here. Eyes are drawn from where I sit downward and opposite the street to a streetlight as a dark moving streak appeared in the corner of my vision and just as quickly disappeared. “What was that“? Just then, another dark streak comes and goes – maybe for two seconds at best. The dark streak launches out of the leafy forest and then disappears back into it. “Bats”, I exclaimed to myself. At the same time, many Moths (30-100) are seen exiting the foliage after birthing. They fly no more than two metres to be instantly attracted to the mini glowing Sun of the streetlight “like Moths around a Flame”. (The quote refers to the song “Falling in Love again”, released in 1930 by Marlene Dietrich and reprised wonderfully many years later in 1976 by Kevin Ayers as a whimsy of a song (love the lap steel), which while writing this piece is now fixed on permanent rotation in my head! Get out! Get out! Enough!! (Can find on YouTube)
Like a well drilled air-force, Bats carry out multiple launches and disappearances into the foliage on predetermined arcs. Sometimes many bats and somehow they never collide. These launches are all in the same direction – towards the Streetlight lamps and away again. There is no slowing down, just Bats on their precise Mission trajectory feasting on Moths that have been attracted to this wonder of the Universe – bright concentrated light. From where I sit, the many Moths appear like small sparkling stars in the lamplight. The Bats see to it that these stars will not be going supernova anytime soon. One by one, the Moths are consumed until none are left. The Bats, with happy tummies disappear back into foliage filled sanctuary and are satisfied to wait until the next Moth birthing. The way our climate is in Kuala Lumpur, they will not have to wait long!
Our massively human altered urban environment is a food resource within Nature. A tiny remnant forest strip in the middle of town providing quality habitat and human technology (the streetlights) have combined to nourish the local ecosystem. The Bats under most circumstances will stay away from strong light as in these streetlights, but their food seeking Sonar means they cannot ignore the Moths ‘served on a plate’ no more than a few metres from the Bat’s sleeping quarters. They are so quick in the execution of the Moth food raids – just two seconds flight time out of and back into foliage sanctuary, that the easy meal opportunity discounts all the discomfort of flying into the light.
AFTER DINNER MINTS
What and/or who has the symbiotic relationship?
Bats and the Moths – Parasitic? It fits the starting definition at the top of the article. Predation (eat,kill) it can only be. The Bats consume and kill Moths for their total advantage. Not quite 100% Genocide occurs within minutes of Moth birthing. At least one or two Moths escape the ‘Flame’ to lay their eggs at home within this skinny habitat in unknowing anticipation of the next Bat feast. Note: Predation is seen by some as another form or sub-set of Parasitic symbiosis – Me? No. Predation is predation. To Predate/Eat are basic instincts tattooed through nature. Predation is a precursor and/or outcome of a Symbiotic relationship. Parasitic symbiosis it is not. (Am open to discussion and/or reading direction in this)
Surely it must be the Streetlights and the Bats in a Commensalistic relationship? Cannot be, as the Streetlights themselves are an artificial construct and not an organism. Humans make the streetlights and the Bats love the feast provided when the light turns on. Bats benefit from Humans without causing harm. Humans are not even aware that they have facilitated (through installing street lights) the Bats happiness. Wonderful! This Commensalistic Symbiotic relationship is due to Urban based human’s need for roadside light at night and the fact that Humans and Bats are organisms. (I still like the streetlight and bat relationship as it is a direct commensalistic two way relationship. The streetlight turns itself on thanks to nature/Sun. The Bat benefits without harming the streetlight and feasts. Humans are the unknowing neutral facilitator by installing the streetlights.
Is this process really Symbiosis though? One party (human), did not intend to create this symbiotic relationship or consider food sources for Bats. Symbiosis is the result of this though, and that is what matters. Streetlights were installed for human comfort. Unintended consequences, contrary to many lines of thought, can sometimes be the best outcomes. Humans need to be informed of their role in creating these facilitated symbiotic relationships. This mini-ecosystem in the City provides insights to natural processes at our doorstep and can open our eyes to the little things that humans can do to maintain and improve the life of other species in urban areas.
Maybe the concept of Symbiosis needs to be reconsidered in terms of (a) it’s strict definition of organisms which are assumed to be living and (b) only two organisms. (Three way symbiosis is being suggested by some) An artificial construct (streetlight) is integral to this tale of symbiotic commensalism. No streetlight = no food and no symbiotic story. The streetlight is essential to both (a) and (b). I suggest participants as an adjunct to organisms and a new term – Facilitation Symbiosis, in which the participants/organisms gain benefit via a neutral third party, organic or not. As with many Nature definitions, research has seen us focus traditionally within natural areas and most of our references derive from the same source.
Given our established and increasing population concentration into Urban areas, now is the time to start adapting these definitions to something tangible for City dwellers that may be witnessed as part of daily existence. This article has discussed just one example of urban ecosystems and the symbiotic relationships within. There are many more symbiotic relationships within our urban environment just waiting to be described and become real to the average person. Understanding our place in this symbiosis can be realised through school curriculum referencing local urban ecological systems. To explore the natural wonders of our urban environment or to carry out practical field studies are just a walk or short train/bus ride away. Truly this is something to be in touch with, understand and enjoy – humans experiencing the “Pleasure of Wild Nature in the City“.
(the quote is the Title of a presentation by Prof Sun Xiaoxiang, a Chinese Landscape Prof. at 1985 AILA Annual Conference at Manly beachside near Sydney. I was glued to the spot for 2 hours ++. From the moment I read and then heard the Title, it became welded into my landscape psych.)
Footnote: Sources for the above chat are few. Mostly Brain scraps, personal observations and hypothesising. A bit of Wikipedia re-confirming rusty concepts learnt some years ago, but that is about it. I welcome any comments to correct or support/expand on the discussion started above.