I have always found fish fascinating. Well, hell, I find all animals fascinating, but I suppose for simple aesthetic intrigue, the fluid movements and interesting lifestyles of aquatic animals have always been a thrill to watch or learn about. Fortunately, with the koi, I had the chance to do both. Inside the house, I was looking at books on the coffee table, and I found one all about koi. Most of it was arcane stuff on their care and maintenance, with some sections even devoted to the professional showing of koi. But there was a chapter leading up to their healthcare that discussed in pleasing detail their biology and physiology. Needless to say, I read it all, and am pleased to say I now know much more about koi fish than I did before, so let me share a brief overview of the animals for my fun fact this evening.The perhaps foremost, possibly obviously so, fact about koi is that they are not wild animals. It's impossible for one to wander off to some distant pond and find schools of koi plying the waters there, just as one wouldn't expect to find packs of golden retrievers hunting caribou in the forest. But, that being said, they are domesticated animals, and this means that they are an intriguing example of what Darwin himself drew the inspiration for his theory from: artificial selection. In this form of selection, a breeder allows only certain offspring to reproduce, those that bear the characteristics which said breeder is looking for. Instead of the most overall fit animal reproducing the most, as in natural selection (the engine of evolution), the animals bearing the most developed traits desired by the breeder are instead selected. Darwin himself did this with pigeons in his backyard, and it wasn't long before inspiration hit him that nature could do the same, only better. In koi, color and overall aesthetic appearance is selected for, leading over the years to the bright orange and yellow fish that swim in fancy ponds.
But, just as golden retrievers were once wild wolves back along their breeding tree, so koi also have a wild origin as the common carp (Cyprinus carpio). The common carp is, well, common all throughout the rivers of Asia and Europe, and this made it easy for breeders to to their thing with it. That sounded wrong. I meant "breed" as in farm and select, not...you know...Moving on after that long introduction (I'm hyper and I feel like a long discourse), we now arrive after years of breeding at the koi which now adorns ponds around fancy places today, and the one which I read all about. Most of this stuff is nothing too new, as I've read about fish before, but the refresh in such a tight context was interesting nonetheless. Koi are remarkably adapted to their watery home, as I learned in detail. They have exceptional eyesight, even under low light conditions. Their sense of touch is compartmentalized into a structure called the lateral line, a shallow groove which runs the length of both sides of the body. This groove is filled with tiny pores, which are in turn filled with tiny, sensitive, hair-like structures. Disturbance in the water around the fish pushes pressure waves into the pores, allowing the koi to detect even minute impulses and vibrations in a directional manner, such as the footsteps of an approaching person. They have no teeth, but instead have rings of bony plates set into the flesh of the mouth, which allow them a wide diet and versatile chewing. Koi also have a remarkable system for buoyancy, making use of a swim bladder. This is a segmented organ lying below the vertebral column, which is filled with air, transported dissolved from the gills. In response to depth, the bladder releases and takes on air, allowing the fish to move up and down in the water column. Their gills are also quite interesting, essentially serving as exposed lungs, with gases diffusing across their membranes. but in order to keep this diffusion going, the fish actually have to actively transport ions into their cells in order to maintain a concentration gradient for water levels, called osmoregulation.
Anyway, that's my fact-vomit about koi, I hope you enjoyed it =)
No comments:
Post a Comment