Biology
- The Biology of Potting Soil
- Elasticity of Ecosystems
- Scientific / Latin Names
- Fascinating Educational Biodomes
- Tasers and Stun Guns vs Bullets
- Fish Farms and the Environment
- The Origins of Life
- Take Fluoride Out of Water?
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
Did you ever wonder why potting soil disappears from houseplant pots? It disappears because it’s organic, and it breaks down over time.
I used to wonder why the amount of potting soil in a house plant pot seems to decrease as times goes by. If you leave a plant in the same pot for years, you’ll notice that it eventually appears to have no soil any more – how can that be?
The confusion comes from the fact that we tend to think of soil—or dirt—as being a mixture of ground and powdered rocks, the results of millennia of erosion. Sand, gravel, and clay are all words for various textures of broken up rock, and they don’t tend to disappear. Soil, however, is something different.
Soil, and particularly potting soil, is mostly the remains of plants that have partially, but not completely, decomposed. A list of ingredients for potting soil might contain peat moss, shredded hardwood bark mulch, composted plant material, perlite (a volcanic glass), and sand. Only the last two ingredients come from rocks and they account for very little of the total mass of potting soil. The rest is organic and it breaks down over time.
Of course, potting soil for indoor house plants is usually sterile because people don’t want insects, earthworms, and other soil dwellers living in their plant pots. This will significantly slow down decomposition of organic material in the soil—and also make it considerably less interesting.
Read about living things in natural soil:
Living Things in Soil
The confusion comes from the fact that we tend to think of soil—or dirt—as being a mixture of ground and powdered rocks, the results of millennia of erosion. Sand, gravel, and clay are all words for various textures of broken up rock, and they don’t tend to disappear. Soil, however, is something different.
Soil, and particularly potting soil, is mostly the remains of plants that have partially, but not completely, decomposed. A list of ingredients for potting soil might contain peat moss, shredded hardwood bark mulch, composted plant material, perlite (a volcanic glass), and sand. Only the last two ingredients come from rocks and they account for very little of the total mass of potting soil. The rest is organic and it breaks down over time.
Of course, potting soil for indoor house plants is usually sterile because people don’t want insects, earthworms, and other soil dwellers living in their plant pots. This will significantly slow down decomposition of organic material in the soil—and also make it considerably less interesting.
Read about living things in natural soil:
Living Things in Soil
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
Ecosystems generally have resiliency built in, but when major change comes, the normal equilibrium is destroyed and the system changes.
In the article What is an Ecosystem, I mention the idea of equilibrium: in theory, ecosystems remain the same for long periods of time because the amount of energy being added by the sun compensates for the energy lost in the lives and deaths of living things. Everything in the ecosystem depends on everything else and all needs are met.
There must be considerable change allowed, however—quite a bit of elasticity—because there are significant natural fluctuations in climate that don’t bring down ecosystems. An unusually cool summer would be a good example (less energy being added). Some plants won’t do as well at cooler temperatures, therefore some other species don’t have as much food and they don’t do as well either. Some species that don’t normally do well in cooler years thrive briefly because the competition is less. But as long as the cool weather doesn’t continue year after year, the normal balance returns.
This is greatly oversimplified of course, but it does suggest that something quite significant has to happen to destroy an ecosystem: the loss of a keystone species perhaps, extreme destruction of habitat, or a long-lasting change in weather patterns.
It’s discouraging to think that humans are causing all three of these things simultaneously in ecosystems all over the world. By the time we learn not to do it, what will be left?
There must be considerable change allowed, however—quite a bit of elasticity—because there are significant natural fluctuations in climate that don’t bring down ecosystems. An unusually cool summer would be a good example (less energy being added). Some plants won’t do as well at cooler temperatures, therefore some other species don’t have as much food and they don’t do as well either. Some species that don’t normally do well in cooler years thrive briefly because the competition is less. But as long as the cool weather doesn’t continue year after year, the normal balance returns.
This is greatly oversimplified of course, but it does suggest that something quite significant has to happen to destroy an ecosystem: the loss of a keystone species perhaps, extreme destruction of habitat, or a long-lasting change in weather patterns.
It’s discouraging to think that humans are causing all three of these things simultaneously in ecosystems all over the world. By the time we learn not to do it, what will be left?
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
Scientific names may seem complicated, difficult to pronounce, and impossible to understand, but they’re systematic and they do have meaning.
Inermicapsifer madagascariensis. It’s the most beautiful scientific name I’ve ever come across. I’ve no idea what the genus name means, but clearly the species name indicates a relationship to Madagascar. Inermicapsifer madagascariensis (can you say it?) is a parasitic tapeworm, but one we needn’t worry about too much. Then there’s Diphyllobothrium latum, a more common tapeworm. For this one I understand the genus name: di means two, phyllo means leaf-like (like phyllo pastry), and bothria are grooves, so the name means “two grooves on a leaf-like structure”—the worm’s scolex, or head. Obviously I would find scientific names a lot more interesting if I were fluent in Latin and Greek.
The idea behind scientific, or Latin, names is that everyone everywhere can refer to species by exactly the same name, no matter what language they speak. Of course the system isn’t perfect. Diphyllobothrium latum has been called Taenia lata, Bothriocephalus latus, Dibothriocephalus latus, Bothriocephalus taenioides, and Dibothriocephalus minor. It’s no exception: many species have left a similar trail of names behind them. Even today, a scientific name can change if scientists determine that a species has been placed in the wrong group. It’s unavoidable.
Nevertheless, the system is useful once you understand how it works—the scientific name, if you know it, is often the fastest way to get information about a species from the scientific literature. And if you use them often enough, Latin names don’t sound so odd. You may even find them beautiful—like Inermicapsifer madagascariensis.
Other topics in biology:
Theories of How Life Began
How Fluoride Works on Teeth
The idea behind scientific, or Latin, names is that everyone everywhere can refer to species by exactly the same name, no matter what language they speak. Of course the system isn’t perfect. Diphyllobothrium latum has been called Taenia lata, Bothriocephalus latus, Dibothriocephalus latus, Bothriocephalus taenioides, and Dibothriocephalus minor. It’s no exception: many species have left a similar trail of names behind them. Even today, a scientific name can change if scientists determine that a species has been placed in the wrong group. It’s unavoidable.
Nevertheless, the system is useful once you understand how it works—the scientific name, if you know it, is often the fastest way to get information about a species from the scientific literature. And if you use them often enough, Latin names don’t sound so odd. You may even find them beautiful—like Inermicapsifer madagascariensis.
Other topics in biology:
Theories of How Life Began
How Fluoride Works on Teeth
Fascinating Educational Biodomes
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
A biodome lets plants and animals live in natural environments far from home, and it lets people visit these ecosystems without traveling large distances.
Biodomes are enclosed environments where scientists have created a specific environment that does not usually exist at that particular place. They populate it with plants and animals that are comfortable there, and provide the required temperature, humidity, light levels etc. on an ongoing basis. Ideally, a biodome works as a complete ecosystem, sustaining itself.
The Montreal Biodome is an example of a climate controlled enclosed ecosystem that successfully recreates four specific environments. The visitor gets to actually visit the different environments and see many plants and animals that live there (except in the case of the polar world, where one just looks in, through glass). What makes it so convincing is the sheer size of the place: there’s actually room for tropical birds to fly, for sloths to climb high into the towering trees, for whole schools of marine fish to come close to the glass and then disappear in the distant depths.
The freedom that the animals have to move around in natural surroundings—surroundings that people are moving through as well—and the size of the biodome, are also what set it apart from zoos and wildlife parks, and make it more educational. It’s well worth the price of admission: I’ll happily go again on my next visit to Montreal. And one day I’d love to visit the Eden Project, and even bigger series of biodomes in southwest England.
Read more in Biology at Suite101
The Montreal Biodome is an example of a climate controlled enclosed ecosystem that successfully recreates four specific environments. The visitor gets to actually visit the different environments and see many plants and animals that live there (except in the case of the polar world, where one just looks in, through glass). What makes it so convincing is the sheer size of the place: there’s actually room for tropical birds to fly, for sloths to climb high into the towering trees, for whole schools of marine fish to come close to the glass and then disappear in the distant depths.
The freedom that the animals have to move around in natural surroundings—surroundings that people are moving through as well—and the size of the biodome, are also what set it apart from zoos and wildlife parks, and make it more educational. It’s well worth the price of admission: I’ll happily go again on my next visit to Montreal. And one day I’d love to visit the Eden Project, and even bigger series of biodomes in southwest England.
Read more in Biology at Suite101
Tasers and Stun Guns vs Bullets
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
The biological basis of a Taser is sound—it briefly hijacks the body’s electrical circuits—but we don’t know everything we need to about the physical effects.
The Taser, or its simpler form the stun gun, is heralded as a non-lethal way to control a dangerous or potentially violent person, a space-age weapon that incapacitates for a brief period of time and leaves no wound. People do die after being shot with Tasers, however, and two fatalities within one week in Canada in the fall of 2007 had many Canadians wondering about the safety of these weapons.
The safety of a Taser is governed by the effects of the electrical shock that it delivers to the human body – it’s basically designed to confuse the brain and nothing more. The biological basis of this is fascinating and well understood. What goes wrong in some instances, however, is not understood, and it’s an area that’s extremely difficult to study: investigators won’t find many people with heart conditions or other medical problems who are willing to take hits from Tasers for the benefit of science. Autopsies of those who do die often don’t yield black and white results.
The Taser debate is an ethical minefield—suspending their use until more is known may well result in more deaths by traditional firearms, while continued use without sufficient knowledge is also unacceptable to many people. At the very least, no one should regard a Taser as a non-lethal weapon.
Do you think we should stop using Tasers until we know more? Start a Discussion.
The safety of a Taser is governed by the effects of the electrical shock that it delivers to the human body – it’s basically designed to confuse the brain and nothing more. The biological basis of this is fascinating and well understood. What goes wrong in some instances, however, is not understood, and it’s an area that’s extremely difficult to study: investigators won’t find many people with heart conditions or other medical problems who are willing to take hits from Tasers for the benefit of science. Autopsies of those who do die often don’t yield black and white results.
The Taser debate is an ethical minefield—suspending their use until more is known may well result in more deaths by traditional firearms, while continued use without sufficient knowledge is also unacceptable to many people. At the very least, no one should regard a Taser as a non-lethal weapon.
Do you think we should stop using Tasers until we know more? Start a Discussion.
Fish Farms and the Environment
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
Fish populations are declining globally. It seems intuitive that fish farming will take some of the pressure off, but there are disturbing objections to fish farms.
Many of us think we’re doing a good thing when we buy farmed fish (and up to a third of fish sold for human consumption today is farmed)—we think we’re taking the pressure off wild fish stocks. There are objections, however, to fish farming, and they’re disturbing enough to make any environmentally conscious person wonder if we should be eating fish at all:
Read about the sea louse issue in Sea Lice and Salmon
- Organic waste (fish wastes and excess food) from open net fish farms pollute the water locally, depleting water of oxygen and creating a dead zone under and near the farm.
- Chemicals used to treat fish diseases are released into the surrounding water, killing wild species.
- Farmed fish, often not native to the area they’re being farmed in, frequently escape into the wild.
- Crowded fish in open net farms are susceptible to diseases and sea lice, and pass them on to wild fish.
- Farmed fish are fed with wild fish—there are more wild fish consumed than farmed fish produced.
Read about the sea louse issue in Sea Lice and Salmon
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
Humans often wonder why we are here. It’s a fascinating question that becomes even more fascinating when we realize what we, and our cells, are really made of.
Trying to comprehend how life began is a bit like trying to imagine what’s on the other side of the edge of the universe. How can there be an edge? It’s hard to grasp that living things are a complex and marvelous product of chemical reactions. How can it be just chemistry?
Two personal revelations stand out for me. One was aided by a microscope, the other, a book. Through the microscope, I saw a ciliated respiratory epithelial cell—one of the cells that line our respiratory system like a field of little automatic brooms, sweeping debris and mucus up and out of the lungs—still busily sweeping in salty solution hours after leaving the body of the person who built it. In the book, I read that scientists believe that mitochondria—the tiny energy producing organelles inside cells—were once organisms themselves that got taken in by larger cells and didn’t die.
Astonishing! Our cells are individual life forms that can live without us as long as their needs are met, and even they have other life forms—or the descendants of other life forms—inside them, allowing them to function. We are built of innumerable individuals that function together to make an organism. It gets even stranger: DNA, the molecule directing all the functions of a cell is made up of elements that have come together through chemical reactions that have little to do with life—but resulted in life. It is, indeed, stranger and more marvelous than fiction.
See Theories of How Life Began for current scientific thought on how those chemical reactions first happened.
Also in Biology.Suite101.com:
How Fluoride Works on Teeth
Two personal revelations stand out for me. One was aided by a microscope, the other, a book. Through the microscope, I saw a ciliated respiratory epithelial cell—one of the cells that line our respiratory system like a field of little automatic brooms, sweeping debris and mucus up and out of the lungs—still busily sweeping in salty solution hours after leaving the body of the person who built it. In the book, I read that scientists believe that mitochondria—the tiny energy producing organelles inside cells—were once organisms themselves that got taken in by larger cells and didn’t die.
Astonishing! Our cells are individual life forms that can live without us as long as their needs are met, and even they have other life forms—or the descendants of other life forms—inside them, allowing them to function. We are built of innumerable individuals that function together to make an organism. It gets even stranger: DNA, the molecule directing all the functions of a cell is made up of elements that have come together through chemical reactions that have little to do with life—but resulted in life. It is, indeed, stranger and more marvelous than fiction.
See Theories of How Life Began for current scientific thought on how those chemical reactions first happened.
Also in Biology.Suite101.com:
How Fluoride Works on Teeth
Posted by
Rosemary Drisdelle
Rosemary Drisdelle
Many municipalities have been adding fluoride to drinking water for years, but now even some experts are saying it doesn’t do anything—anything good that is.
Fluoride has been added to drinking water since the late 1940s because of evidence that communities with a higher level of natural fluoride in their water supply had a lower incidence of dental cavities (see How Fluoride Works on Teeth). Soon, most North Americans were drinking fluoridated water and some European countries adopted the practice as well. Oral products with added fluoride became the norm… and the incidence of cavities went down. People drinking well water without fluoride were advised to give children fluoride drops while their teeth were still developing.
I’ve long suspected that the whole fluoridated water thing is a bit of a lie: if ingested fluoride only affects developing teeth, what’s the point in giving it to millions of adults? If direct contact with erupted teeth has the best effect, why not just use toothpaste with fluoride and leave it at that? Others were much more outspoken one way or the other, verging, it seemed, on fanatical, but now even respected experts are speaking up about the lack of effectiveness and possible health hazards of a steady diet of fluoride.
I’m now convinced that fluoride in water is a bad idea, and I’m on the fence about other fluoridated products. Toothpaste? Maybe. Fluoride treatments at the dentist? Maybe. Mouthwash and table salt? No.
What do you think? Start a discussion.
I’ve long suspected that the whole fluoridated water thing is a bit of a lie: if ingested fluoride only affects developing teeth, what’s the point in giving it to millions of adults? If direct contact with erupted teeth has the best effect, why not just use toothpaste with fluoride and leave it at that? Others were much more outspoken one way or the other, verging, it seemed, on fanatical, but now even respected experts are speaking up about the lack of effectiveness and possible health hazards of a steady diet of fluoride.
I’m now convinced that fluoride in water is a bad idea, and I’m on the fence about other fluoridated products. Toothpaste? Maybe. Fluoride treatments at the dentist? Maybe. Mouthwash and table salt? No.
What do you think? Start a discussion.