When the weather is just right the larvae will transform into their adult form.  Now these poor buggers don’t have much time to make the next generation.  So they head off and mate in swarms.

Although bugs have always been a nuisance to us humans they are important for the ecosystem.  Midge fly larvae are food to some fish and I’m sure the spiders don’t mind the adults either.  So patch up your screens, drain the pool, and avoid turning on lights at night to prevent these critters from living in your home.

Sources:
http://lancaster.unl.edu/enviro/pest/factsheets/262-95.htm
http://www.thestar.com/news/gta/article/638591
http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1ARTA0005278

Now I have talked about light absorption before (see Colour Vision) so I won’t go over the details.  The device used is called a Pulse Oximeter; it has a pair of LED lights that shine a red visible light and an infared light through the finger.  There is a detector on the other side to measure how much of the light was absorbed.  Since oxgenated blood is red, then the light  picked up by the detector should also be red. If the oxygen level is high, the red blood will reflect the red light.  So now this is making sense, but there are also veins in the finger too.  So how does it measure just the blood in the arteries? Well that’s were the “pulse” part of the name comes in.

The device only measures when there is a pulse.  Pulses only occur in the arteries because this is where blood is sent after being pumped from the heart.  The flow in the veins does not have a pulse, it is basically a passive flow of blood back to the heart.  So, the Pulse Oximeter only measures the colour of the blood that pulses through the arteries; therefore capable of measuring the heart rate as well as the blood oxygen levels.

Sources:
http://www.pulseox.info/pulseox/how.htm
http://en.wikipedia.org/wiki/Pulse_oximeter
http://www.nda.ox.ac.uk/wfsa/html/u05/u05_003.htm

Fireflies use this production of light to communicate with one another, particularly with finding mates.  But they are not the only animals capable of producing light.  This ability is known as “bioluminescence” and can also be found in many creatures of the sea.

Source:
http://learn.genetics.utah.edu/content/begin/dna/firefly/

The Light Spectrum

Why do we see the colours that we see?  Why do some things appear white, blue, yellow, or purple?  Well I hope to shine some light on this question.  Some of us already know about the light spectrum, and that humans can only see a small proportion of it.  This small range is aptly named “visible light”.  Leave it to humans to name things with respect to themselves.  I say this because some animals can see outside of this range.  Bees, for example, are capable of detecting the higher-frequency Ultra-Violet light waves.  Additionally, the visible range of a Mantis Shrimp starts in UV and reaches down into the Infra-red.  But getting back to us humans.  In the visible light spectrum each colour is characterized by its own specific light wavelength.

So back to our original question, why do we see the colours that we do?  The process is more complex than I am going to get into for the purpose of this article.  Basically certain materials absorb specific wavelengths of light and reflect the rest.  This reflected light it what is transmitted to our eye and perceived as the colour of that object.  So, plants which appear green are actually reflecting green light and not using it at all.

So here’s some scientific proof that your mother was right yet again.  White is the best colour of clothes to wear on a hot, sunny summer’s day, and black is the worst.  When we see white it is because all of the different colour wavelengths are reflected from the material, whereas black is a result of all these wavelengths being absorbed, resulting in heat build up from the light energy.  This has been adapted into the animal kingdom and is very important for animals in polar regions such the polar bear or Harp seal pups.  Their fur is white and their skin black.  The white fur reflects the sun down to the black skin where it absorbs the light energy which is then transferred into heat energy.  As you can see this would be very advantageous for an animal in order to stay warm in such a cold climate.

T. nutricula is found in all the world’s oceans, and is a 4-5 mm clear jellyfish with a bright red stomach inside. After hatching from an egg, the baby jellyfish (“hydriods”) settle on the ocean floor, as most jellyfish do, in a colony. When conditions are right, the hydroids break off and turn into the bell-shaped jellyfish we all recognize. Once it reaches maturity, the jellyfish releases eggs to form the next generation.

What makes T. nutricula unique is that it can reverse its own aging to prevent death. Any stage of its life can reverse to any previous stage, including all the way back to a hydroid colony. This makes the jellyfish “biologically immortal”, meaning that age has no effect on when the jellyfish dies. Unfortunately, the jellyfish can still be eaten and therefore die at any age, so there’s probably not any thousand-year old jellyfish around.

There are other species considered to be biologically immortal. Bristlecone pines have been shown to live for thousands of years. Tardigrades and bacterial colonies are also among the immortal animals. Some people believe that humans, with future technology, can become biologically immortal. I’ll believe it when I get my flying car.

In some martial arts and seen in film, people have gone unconcious when a certain part of their neck is pressed.  This can be done because if the carotid sinus is pressed it will increase the blood pressure in only that area.  As a result the baroreceptors within the carotid sinus will send a signal to the heart to slow down in order to lower the increased blood pressure.  Since the blood pressure in the rest of the body has not increased, this will cause the blood pressure to fall too low resulting in unconciousness.  Unconsiousness occurs because there is not enough blood being transported to the brain; if the body is horizontal then the blood does not have to work against gravity in order to reach the brain.

Sources:

http://dictionary.reference.com/browse/carotid sinus
http://www.healthscout.com/ency/68/74/main.html
http://en.wikipedia.org/wiki/Carotid_sinus

Hooded seal inflating and everting its nostrils.

Another interesting fact about these animals is that the pup only nurses for a total of 4 days, which is the shortest lactation period of any mammal.  The mother’s milk contains 60% – 70% fat.  The pup will nurse almost non-stop until it has doubled in size from 24kg to 47kg within the 4 days.  The mother will then leave and the pup will fast on its fat reserves for a few weeks until it is old enough, and slim enough, to swim and catch fish.

Sources:
http://www.pinnipeds.org/species/hooded.htm
http://eol.org/pages/328632>http://eol.org/pages/328632

In 2009 researchers have discovered that when BBG is administrated through intravenous injection (IV) 15 minutes or even up to 6 hours after the original spinal cord injury there is a great improvement in motor control compared to those with no treatment (note: this study was done on rats and all research experiments have to be approved by an ethics board).  The rats given the BBG treatment had reduced secondary SCI and were able to walk with a limp.  The only side effect noted was blue colouring of the skin and no known toxicity, except in special cases.  This has great implication for future use because the previous compound found to have the same positive effects on SCI, oxidated ATP, had to be injected directly into the spinal cord and had potential toxic side effects.

Sources:

http://news.nationalgeographic.com/news/2009/07/photogalleries/blue-rats-food-dye-heals-pictures/index.html

http://www.medscape.com/viewarticle/706763 (may require a google search: "Blue Dye Stops Spinal-Cord-Injury Progression")

http://www.pnas.org/content/106/30/12489.full

Researchers have successfully found a way to restore red-green vision to colour blind adult Spider Monkeys.  The monkeys were trained to touch coloured dots with their head on a touch screen.  The screen was filled with grey dots of varying sizes and a select cluster of the dots were coloured; the select cluster of dots varied for each session.  This was similar to the images used to determine colour blindness in humans: a circle of dots with select dots being coloured differently to creat the shape of numbers (see one here).  When done correctly the monkeys were given grape juice as a reward.  Some of the monkeys had normal colour vision while others had colour blindness.  The colour blind monkeys were unable to detect the red or green coloured dots among the grey ones.  They were not rewarded on these occasions and were said to have gotten frustrated and would even shake the screen.  Two of the monkeys with colour blindness were given gene therapy via an altered virus injected behind the retina of the eye.  The gene that the virus inserted was that for the red pigments found in cone cells (which detect colour) of the eye.  After 20 weeks the two monkeys were capable of seeing red and green; as was shown by their increased ability to correctly identify the coloured dots.  This could have great implications for humans; colour blindness is the most common genetic disorder for humans.  It is also interesting because it has been believed that the adult human brain is unable to undergo new changes.  This study showed that adult monkeys were able to take in the new gene to alter the activation of cone cells in the eye, suggesting that the brain is capable of making alterations during adulthood.

Sources:

http://news.nationalgeographic.com/news/2009/09/090916-color-blind-gene-monkeys.html

http://www.nature.com/news/2009/090916/full/news.2009.921.html

Neon tetras (Paracheirodon innesilich) are a popular aquarium fish that appear to have a glowing horizontal stripe along their side.  This stripe is iridescent and is incapable of glowing in the absence of light.  Iridescence is caused by the reflection of light off of the many transparent layers attributing different refractive indexes.

It has been studied that the colour of the stripe changes under differing conditions (see article here).  The tetra’s stripe is violet or blue when under dim-light conditions.  But when exposed to more intense light the cytoplasm of the cells within  transparent layers thicken so that longer wavelengths are emitted creating a green colour.  It is thought that the layers contain a rhodopsin-like molecule (which our eyes have) to induce the thickening of the cytoplasm through osmotic processes via sodium channels.