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Today, we talk about another fast moving plant, called mimosa pudica, AKA. Shame plant, shy plant, touch me not, or the tickle me plant. This little plant will curl up its leaves when they are touched.
Here’s a video that shows the tickle me plant in action.
Mimosa Pudica – The Sensitive Plant
Here’s an article on growing and caring for mimosa pudica as a house plant.
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We move and eat via our nerves and muscles, but there are some plants that have no nerves and no muscles, and yet they still move and eat. Today, we talk about the Venus flytrap, and how it why it does what it does.
Special thanks to @StoneyJehker34, for the question and the topic.
Here’s a video showing the Venus flytrap in action.
Here are a couple of articles about this interesting little plant.
Venus Flytraps Are Even Creepier Than We Thought
Here’s a paper on how the plant counts touches against its trigger hairs to decide how much substance to produce to digest its prey.
The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake
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It seems that most of our DNA is dormant. It doesn’t encode for protein production. Some of this supposedly dormant DNA has recently been shown to have important functionality, but there still seems to be much more information present than is used.
Here’s an article on the debate over how much of our DNA is functional.
Here’s an article on gene sequences that appear to have come from other organisms, entering our genetic code through horizontal gene transfer.
Humans may harbor more than 100 genes from other organisms
Here’s an article on DNA sequences that have been written into our DNA by viruses, some of which might still be capable of making us sick.
An ancient retrovirus has been found in human DNA – and it might still be active
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Sometimes, evolution can take it back. Many cave dwelling animals have lost their eyes. Theories as to why this happen range from genetic drift, to mutations that improve other senses interfering with the proper development of eyes, to the energy cost of growing and maintaining vision. I suspect that it has to do with how easily injured eyes are when they don’t work. I’ve never seen that brought up by scientists; maybe you have to go blind to get it.
Here’s an article on the kiwi bird and how it may be losing its sight as a species. Special thanks to @seeingwithsound for the article and pointing me to this topic.
New Zealand’s iconic kiwi birds may be losing their sight
Here’s an article on changes in the brains of sightless animals.
Thanks to evolution, blind cave-dwellers are rapidly losing the visual parts of their brains
Here’s a paper on animals that have given up eyes, and how and why they may have done so.
Evolution of eye development in the darkness of caves: adaptation, drift, or both?
Here’s an article on blind cave fish that includes a video.
How This Cave-Dwelling Fish Lost Its Eyes to Evolution
And an article on how the offspring of blind cave fish can regain their sight.
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Sometimes, you feel like something is wrong. Most of the time, it’s just a feeling; it doesn’t mean anything. But, every now and then, something is wrong, you really are in danger, you really should be afraid.
Here are some articles on how humans can react to the unconsciously sensed smell of fear in the perspiration of others.
Humans Can Sense ‘Smell Of Fear’ In Sweat, Psychologist Says
The smell of fear is real and it’s contagious
Study Says Humans Can Smell Fear, Emotion Is Contagious
Here’s a paper on the human reaction to putrescine, a chemical associated with death and decay. Even when we don’t consciously notice the smell, we’re instinctively made nervous by its presence.
Here’s a talk by a woman who felt unexplained feelings of dread within her new home. At first, she thought it was a ghost, but eventually she discovered it was something far more deadly.
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“
To suppose that the eye, with all its inimitable contrivances… could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree… Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist… and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered a real1.
“
Charles Darwin (1809–1882)
Darwin included a section in his book, “On the Origin of Species,” called, “Problems With the Theory.” It included the Cambrian explosion, covered in the previous episode, and the development of complex organs like the eye. Today, using things we’ve learned since Darwin’s time, we look at how eyes evolved.
Here are a number of articles with further information.
Evolution: Library: Evolution of the Eye
Evolution of the vertebrate eye: opsins, photoreceptors, retina and eye cup
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Between 520 and 550 million years ago, a sudden explosion of animal types appear in the fossil record. This example of rapid evolution is known as the Cambrian explosion. Theories of how and why it occurred range from the notion that it didn’t happen at all, to a spike in oxygen levels, to the advent of the sense of vision.
Here’s an article that includes an animation of some of the oddball animals that appeared and disappeared during the Cambrian period.
Evolution: Library: The Cambrian Explosion
Here’s an article that describes the link between oxygen and predators.
What sparked the Cambrian explosion?
And here are a couple more articles with more information on the Cambrian explosion.
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In today’s rather short episode, we talk about the first creatures to have developed a centralized nervous system, though not a central nervous system as of yet. It was a simple worm like creature, with a nerve cord running along the length of its body, and an extra-large bundle of nerves toward its mouth. For worms and other invertebrate animals, like crabs, lobsters, octopuses, squid, slugs and snails, the nerve cord runs along the belly of the creature. For what would become vertebrates, including us, the main nerve cord runs along the back. Apparently, for reasons unknown, some of the worms flipped over, and decided to live their lives upside-down.
This month has included some unusually long episodes. To leave room for the upcoming Halloween special, this and the next couple of episodes are unusually short. Check back on the 31st for, “Be Afraid.: when reason can get you killed.”
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A stun gun works by passing electricity through your muscles, causing uncontrollable contractions. An electric eel, which is actually a type of fish, can do the same thing. There is a single celled creature that can conduct electrons from hydrogen sulfide in the soil, to oxygen dissolved in the water. Almost every living cell has an electric charge. Multicellular life has found a way to use electricity to send long distance messages from one part of the organism to another. Today, we talk about electricity, life, and some slightly grotesque experiments that have been done with the relationship between the two.
Here’s an article on electric currents applied to recently deceased human body’s, that caused them to move.
1800s doctors conducted weird electrical experiments on corpse brains
Here are a couple of articles about single celled life and nanowires that they grow to conduct electricity.
Bacteria buzzing in the seabed
Biological wires carry electricity thanks to special amino acids
Here’s an article about experiments done that altered the electrical properties of cells that changed the way the organism grew. This included eyes on the tales of tadpoles, and hints of being able to regrow severed limbs in creatures that do not normally possess such a capacity.
It’s Electric: Biologists Seek to Crack Cell’s Bioelectric Code