Animal Coverings Facilitated

Transcription

1 Animal Coverings Facilitated Students will explore various animal coverings with their senses, with help from a high-powered microscope. Description: Explore fur, feathers and scales like never seen before through a high-powered microscope! Location at the Zoo: Wings of the World Penguin Exhibit Materials: cart, ipad, bag of various biofacts, animal pictures Background: Animals can be classified into different groups based on similar physical characteristics. One of the easiest separators is by body coverings. This activity will focus on three groups: mammals have hair or fur; reptiles have scales; birds have feathers. Of course there are always exceptions to the rule. For example, whales are mammals, yet they seemingly don t have hair or fur. Whales do in fact have hair, but only during the early years of their lives. Not all coverings are created equal. HAIR & FUR Hair and fur is made up of dead cells that don t change once they have grown out of the skin. There is no difference between the two; the length of hair and pattern of where it grows is an individual and species trait. Animal hairs can be divided into groups: Guard hairs form outer coat and provide protection Fur or wool hairs form inner coat and provide insulation Tactile hairs (whiskers) found on the head and provide sensory functions Other tail and main hair, human hair Parts of hair on the microscopic level: Definitions of hair parts: Medulla hollow core filled with shrunken cells and air. Not always present. Cortex middle and largest layer, composed of spindle-shaped cells in bundles. Pigments in the cortex give human hair its color.

2 Pigment granules small, dark, solid structures granular and smaller than cortex cells. Vary in color, size and distribution in a single hair. Human hair pigment granules are commonly found toward the cuticle (except red heads, where it is found near the medulla). Animal pigment granules are commonly found toward the medulla. Cuticle translucent outer layer of scales; always point from root of hair. Types of cuticle scales Crown-like Bat hair (bat & small rodent hair, rarely on humans) Petal-like (mink, seals, cats, other mammals, never humans) Mink hair Flattened (human hairs, many animals) Human hair FEATHERS All birds have feathers and only birds have feathers. Most feathers share similar structures, and some are adapted for special roles. Feathers support flight, visual communication, waterproofing, and many other functions. Definitions of feather parts: Shaft main, central support that runs the length of feather. Vane part that unzips and rezips; gives feather overall shape. Rachis part of shaft where vanes are located. Calamus/Quill base of shaft. Barbs intricate structures that form the vane. Barbules parts of barbs. A single barb can contain hundreds of barbules.

3 Barbicels tiny hooks that connect barbules (very similar to the action of Velcro!) SCALES/SKIN All animals shed their skin. Humans shed 1.5 million skin cells every hour. Similar to

4 humans, some reptiles shed a little at a time such as turtles, alligators, and most lizards. Snakes shed all their skin at once, leaving it behind in one piece. Turtles Turtles shed their scales a bit at a time. Even their shell, which grows with them throughout their lives, sheds pieces called scutes. Scales are a protective, waterproof adaptation that reduces evaporation from the animal s body. Scales are highly variable in size, thickness, function and color. Definitions of scale/skin parts: Epidermis - The outer layer of skin or scales which is shed on a regular basis. Dermis - The inner layer of skin. This layer contains pigment cells that give scales their color. Keratin protein that scales, fingernails and feathers are made of. Fun fact - some lizards will eat their own shed! Set Up: Make sure the ipad is on. On the home screen, click on the Photos application. At the top of the screen, there should be a list of options. Click on Albums to find the Microscope Activity album and click on it to open. Each picture will show up as a thumbnail. To open it, click on it once. It will bring up the labeled photo of your choice. To return to the thumbnails, click Microscope Activity in the upperleft hand corner. Fur/Hair Human Hair 10x and 40x - A human hair appears solid when magnified and shows the hair s color. Only the cuticle is visible at 40x magnification and the hair has a textured appearance. It is obvious at this magnification if human hair has been modified in any way such as with hair dye. Human hair keeps us warm and also acts as a touch sensor (like eyelashes) to alert us to foreign bodies. Orangutan Hair 10x and 40x - Orangutan hair has similar traits and uses to human hair but thickly covers a larger portion of the body. It is usually reddish-orange in color, thin, and shaggy. Polar Bear 40x - Polar bear fur looks very different than human hair under a microscope. While it appears white to the naked eye, it is in fact colorless because it is both hollow and transparent. The hair looks white because the air spaces in each hair scatter light of all colors. The color white becomes visible to our eyes when an object reflects back all the visible wavelengths of light rather than absorbing some of the wavelengths. Under magnification, polar bear hair reveals its true nature, transparent with a distinct hollow center. This hair configuration allows for extra

5 Feathers warmth and makes the hair waterproof, as water can easily be whisked away with a few shakes after swimming. Porcupine 10x - A porcupine quill looks very different than the first two but is really a modified hair coated with a thick plate of alpha-keratin (the key structural component our hair and nails are made of). The primary function of quills is defense; they are quite sharp and can be released on contact. Under magnification, prehensile-tail porcupine quills show their light, spongy center and how thick their keratin coating is. Quills are not hooked like fishhooks but towards the tip, they do have microscopic, scale-like barbs that are seen under magnification. Wolf White 40x and Wolf Black 40x - Wolves have two kinds of hairs. There are the long, stiff hairs of the outer coat, called "guard hairs". Wolves also have an "undercoat" of soft fur that grows thick in the winter and helps to insulate its body from the cold. This hair is shed in the spring and summer in large sheets and chunks. Wolves use their hair to communicate. By raising or flattening its hair, a wolf may signal aggression, anger or dominance. By holding its "hackles", or the hair on the back of its neck, stiff, for instance, a wolf signals aggression or dominance. The hair around the face can also puff out making the wolf's aggressive stare look even larger to a potential enemy. Blue and Gold Macaw 10x - A macaw s feathers do help this bird fly, but what is usually most noticeable is the coloration of the feathers that helps members of their species identify each other. When viewing a magnification of a macaw feather, the color of the feather is still seen in the barbs of the feather. Barred Owl 10x and 40x - Owl feathers are also made for flying but lack the bright colors of macaw feathers. Instead, the coloration is meant for camouflage but owl feathers also have a special feather adaptation that allows these birds to fly almost silently. It is a fringe-like edge called a fluting or a fimbriae which breaks down air turbulence during flight, muffling the sound that prey might be able to hear otherwise. An alternate theory is that the flutings actually shift the sound energy to a higher wavelength that is beyond human and most prey s hearing. The naked eye can see the little fringes at the end of an owl feather but it is most easily seen under magnification where it looks like little bristles at the end of the barbules. Duck 10x and 40x Waterfowl, like ducks, feathers are for flight and protection. Contour feathers collectively serve as a protective outer shell. They overlap one another much like shingles on a roof, forming an almost impenetrable barrier to wind and moisture. Feathers are also held in place by specialized muscles just under the skin. Using these muscles waterfowl can fluff up their feathers and move them back into position at will. Emu 10x and 40x - Unlike the macaw and owl, emu feathers aren t made for flight. Emus are terrestrial birds with absolutely no flying abilities. The barbs found on a typical emu feather are widely spaced and don't have the usual hooks that attach to the other barbs. Instead, each barb hangs loosely and gives emu feathers a hair-like appearance. Emus are also the only bird that have double feathers or a feather that grows two shafts. Looking at the magnified picture of an emu feather, the barbs almost appear to be hair strands. Magellanic Penguin 10x and 40x Penguin feathers are also not made for flight, at least not in the sky. Penguins fly underwater and have unique feathers that act like a wet suit, offering them protection. Their coloration allows for camouflage from both above and below in the water with their black backs and white bellies. Their smooth plumage provides waterproof insulation by trapping air against their bodies, plus it gives them extra buoyancy in cold seas. Penguins have more feathers per square inch than any other bird in the world.

6 Scales All reptiles shed their skins, referred to as ecdysis, in a manner that differs from species to species. Snake Shed 10x and 40x - Snakes shed or "slough" their skins in one piece, including eye caps. In general, snakes will slough at least once a month. The frequency of shedding depends on many factors: species, age, nutritional and reproductive status, the presence of skin parasites or bacteria, and ambient enclosure temperature and humidity. Generally speaking, younger snakes will shed more frequently than adults and shedding often precedes mating and giving birth. Box Turtle Scute 10x and 40x - A turtle s shell is primarily made up of bone plates that are covered in scutes. These scutes are shed individually and make up a type of skin that covers the bony structure underneath. Magnified, little cracks and the roughness of the scute are very easily seen. Activity: Introduce yourself to the group and invite them to touch and explore the animal coverings. We know that animals are covered in different ways. Have the group name some examples. Some have hair, feathers, scales, shells, skin, etc. Because you are stationed near the penguin exhibit, it might be easier to bring visitors over by starting with penguin feathers. For younger groups, watch as they explore the touchable feathers, furs and reptile biofacts. Be receptive to what they are drawn to and focus on taking their observations deeper. Allow them to share their voice by asking questions about what they see, feel and think. For example, which feather is softer? For older groups, spark their interest by allowing them to explore the touchable biofacts. Be receptive to what they are drawn to and focus on taking their observations deeper. Allow them to share their voice by asking questions about what they see, feel and think. Ask questions that help them focus on comparing the biofacts. For example, which of these feathers seems to have more of a fringed vs straighter edge? Fringed feathers create less resistance as they move through the air, making flight almost completely silent. What animal might benefit from silent flight? Owls, who hunt for their prey at night. For all groups, ask if they have they ever wondered what this feather looks like zoomed in. See if they can use their eyes to zoom in on the feather closely. What do they see? Microscopes help us see things very close up, where our eyes can only see so far. Explore the prepared slide photos and point out a few different things that will help them understand how coverings help animals survive. For instance: Feathers: Velcro-like to keep the pieces together and smooth = better for flying, and keeping heat in/cool out. Fur/hair: different thicknesses to protect skin, keep heat in/cool out, different colors to blend in/stand out (skunks), polar bears have hollow hairs to keep their heat in and the extreme cold out. Porcupine quills are enlarged hairs. Whiskers are sensory receptor hairs (catfish do not have true whiskers, although they serve a similar purpose as mammal whiskers). Scales: create a waterproof, protective barrier allowing reptiles to live in dry parts of the world. Conclusion Animals have different body coverings to protect them and help them survive. If they could choose, would they want their skin to be covered in fur, feathers or scales? Why? It s okay to get a little silly. Send them on their way by encouraging them to keep an eye out for animals at the Zoo that have interesting coverings and to think for a minute about how it might help the animal survive.