Kilback

Meanwhile, crabs have been known to repeatedly rub a spot on their bodies where they've received an electric shock.And even sea slugs flinch when they know they're about to receive a noxious stimulus.That means they have some memory of physical sensations.We still have a lot to learn about animal pain. As our knowledge grows,it may one day allow us to live in a world where we don't cause pain needlessly.

because we may be causing these animals unnecessary suffering.Scientific experimentation,though controversial, gives us some clues. Tests on hermit crabs show that they'll leave an undesirable shell if they're zapped with electricity but stay if it's a good shell. And octopi that may originally curl up an injured arm to protect it will risk using it to catch prey.That suggests that these animals make value judgements around sensory input instead of just reacting reflexively to harm.

So an oyster may recoil when squirted with lemon juice, for instance, because of nociception.But with such a simple nervous system,it's unlikely to experience the conscious part of pain.Other invertebrate animals are more complicated, though,like the octopus,which has a sophisticated brain and is thought to be one of the most intelligent invertebrate animals.Yet, in many countries, people continue the practice of eating live octopus.We also boil live crawfish, shrimp, and crabs even though we don't really know how they're affected either.This poses an ethical problem.

We've reached the point that research has made us so sure that vertebrates recognize pain that it's illegal in many countries to needlessly harm these animals. But what about other types of animals like invertebrates? These animals aren't legally protected, partly because their behaviors are harder to read. We can make good guesses about some of them, like oysters, worms, and jellyfish. These are examples of animals that either lack a brain or have a very simple one.

However, we get clues from observing how animals behave.Wild, hurt animals are known to nurse their wounds,make noises to show their distress, and become reclusive.In the lab, scientists have discovered that animals like chickens and rats will self-administer pain-reducing drugs if they're hurting. Animals also avoid situations where they've been hurt before, which suggests awareness of threats.

The second part is the conscious recognition of harm.In humans, this occurs when the sensory neurons in our skin make a second round of connections via the spinal cord to the brain.There, millions of neurons in multiple regions create the sensations of pain.For us, this is a very complex experience associated with emotions like fear,panic,and stress,which we can communicate to others.But it's harder to know exactly how animals experience this part of the process because most them can't show us what they feel.

In vertebrates, including humans,pain can be split into two distinct processes.In first, nerves and the skin sense something harmful and communicate that information to the spinal cord.There, motor neurons activate movements that make us rapidly jerk away from the threat.This is the physical recognition of harm called nociception,and nearly all animals,even those with very simple nervous systems,experience it.Without this ability, animals would be unable to avoid harm and their survival would be threatened.

Humans know the surprising prick of a needle,the searing pain of a stubbed toe,and the throbbing of a toothache.We can identify many types of pain and have multiple ways of treating it.But what about other species?How do the animals all around us experience pain?It's important that we find out.We keep animals as pets, they enrich our environment,we farm many species for food,and we use them in experiments to advance science and human health.

Animals are clearly important to us,so it's equally important that we avoid causing them unnecessary pain. For animals that are similar to us, like mammals,it's often obvious when they're hurting.But there's a lot that isn't obvious,like whether pain relievers that work on us also help them. And the more different an animal is from us,the harder it is to understand their experience.How do you tell whether a shrimp is in pain?A snake? A snail?

Now that we can determine a fossilized feather's color, paleontologists are looking for more fossils with well-preserved melanosomes. They've found that a lot of dinosaurs, including velociraptor,probably had feathers,meaning that certain films might not be so biologically accurate. Clever girls.

The scientists then chose 20 feathers from one fossil and found that the melanosomes in all 20 looked alike,so they became pretty sure this dinosaur was one solid color.They compared these microraptor melanosomes to those of modern birds and found a close similarity, though not a perfect match, to the iridescent teal feathers found on duck wings. And by examining the exact size and arrangement of the melanosomes, scientists determined that the feathers were iridescent black.

Of course, it's more complex than this.The melanosomes are packed together inside cells, and other factors, like how the melanosomes are arranged within the feather, also matter.Let's return to the microraptor fossil.When scientists examined its feather imprints under a powerful microscope,they found nanostructures that look like melanosomes.X-ray analysis of the melanosomes further supported that theory. They contained minerals that would result from the decay of melanin.

A portion of the transmitted light then reflects off the back surface.The two reflected waves interact.Usually they cancel each other out, but when the wavelength of the reflected light matches the distance between the two reflections,they reinforce each other.Green light has a wavelength of about 500 nanometers,so melanosomes that are about 500 nanometers across give off green light,thinner melanosomes give off purple light, and thicker ones give off red light.

Light is basically a tiny electromagnetic wave traveling through space.The top of a wave is called its crest and the distance between two crests is called the wavelength.The crests in red light are about 700 billionths of a meter apart and the wavelength of purple light is even shorter,about 400 billionths of a meter,or 400 nanometers.When light hits the thin front surface of a bird's hollow melanosome, some is reflected and some passes through.

Most feathers contain just one or two dye-like pigments.The cardinal's bright red comes from carotenoids,the same pigments that make carrots orange,while the black of its face is from melanin,the pigment that colors our hair and skin.But in bird feathers,melanin isn't simply a dye.It forms hollow nanostructures called melanosomes which can shine in all the colors of the rainbow. To understand how that works, it helps to remember some things about light.

But making sense of the evidence requires careful examination of the fossil and a good understanding of the physics of light and color.First of all, here's what we actually see on the fossil:imprints of bones and feathers that have left telltale mineral deposits.And from those imprints, we can determine that these microraptor feathers were similar to modern dinosaur,as in bird, feathers.But what gives birds their signature diverse colorations?

This is the microraptor,a carnivorous four-winged dinosaur that was almost two-feet long,ate fish,and lived about 120 million years ago.Most of what we know about it comes from fossils that look like this.So, is its coloration here just an artist's best guess?The answer is no.We know this shimmering black color is accurate because paleontologists have analyzed clues contained within the fossil.

They are beautiful but terrifying,especially if you or your town is in its path.In that case, no one,not even tornado chasers like me,enjoy watching thing unfold.Just like everything, however,tornadoes do come to an end.When the temperature difference disappearsand conditions grow more stable,or the moisture in the air dries up, the once fierce parent storm loses momentum and draws its tornado back inside.Even so, meteorologists and storm chasers like me will remain on the lookout,watching, always watching to see if the storm releases its long rope again.

Then, the mesocyclone's lower part becomes tighter,increasing the speed of the wind.If, and that's a big if,this funnel of air moves down into that large, moist cloud base at the bottom of the parent storm,it sucks it in and turns it into a rotating wall of cloud,forming a link between the storm that created it and the Earth.The second that tube of spinning cloud touches the ground,it becomes a tornado.Most are small and short-lived,producing winds of 65-110 miles per hour,but others can last for over an hour,producing 200 mile per hour winds.

When all these things are in place,a vortex can develop enclosed by the storm,and forming a wide, tall tube of spinning air that then gets pulled upwards.We call this a mesocyclone.Outside, cool, dry, sinking air starts to wrap around the back of this mesocyclone,forming what's known as a rear flank downdraft.This unusual scenario creates a stark temperature difference between the air inside the mesocyclone, and the air outside,building up a level of instability that allows a tornado to thrive.

Any storm is formed when condensation occurs,the byproducts of the clouds.Condensation releases heat,and heat becomes the energy that drives huge upward drafts of air.The more condensation and the bigger the storm clouds grow,the more powerful those updrafts become. In supercells, this rising airmass is particularly strong.As the air climbs, it can change direction and start to move more quickly.Finally, at the storm's base,if there is a lot of moisture,a huge cloud base develops,giving the tornado something to feed off later, if it gets that far.

These are especially powerful, towering thunderstorms called supercells.Reaching up to over 50,000 feet,they bring high force winds,giant hailstones, sometimes flooding and great flashes of lightning, too.These are the kinds of storms that breed tornadoes,but only if there are also very specific conditions in place,clues that we can measure and look out for when we're trying to forecast a storm. Rising air is the first ingredient needed for a tornado to develop.

They call me the tornado chaser.When the wind is up and conditions are right,I get in my car and follow violent storms."Crazy," you say? Perhaps, but really I chase these sky beasts to learn about them.I want to share with you what I know.Tornadoes are rapidly rotating columns of air that form inside storms that connect with the ground via a funnel of cloud.When that happens, they tear across the Earth, posing a huge threat to life and property.

Because of this, there's a great deal of research into these phenomena,but the truth is, there's still a lot we don't know about how tornadoes form.The conditions that may give rise to one tornado won't necessarily cause another.But we have learned a lot since people first started recording tornadoes,like how to recognize the signs when one is brewing in the sky.Are you coming along for the ride?Tornadoes begin with a thunderstorm but not just any thunderstorm.