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Do animals with very small eyes see microscopic objects?


I understand that many small creatures have very elementary eyes: they are not scaled-down versions of the human eye but as I understand it often just light-sensitive organs for detecting movement.

However, a mouse I would guess has an eye that is like the human eye but probably less than 1% the size. So does that mean that a mouse sees details that humans can't?

There has been recent evidence that ants might recognize their own reflections. Now, I know the structure of insect eyes is very different from mammalian eyes but if indeed they can recognize themselves in a mirror, that implies that their eyes can perceive very small details.

I could also imagine that things like wavelength mean that details of very small objects simply can't be perceived by bouncing visible light off of them -- that is why their are electron microscopes and so I could believe that mice, etc. can see bacteria, etc. any better than we can.


The Human Eye Facts, Functions, Structure and Problems

What do you know about the eye definition biology? Just learn about human eye facts and you will get precious information about it. You can define the eye as an organ of vision which makes you visualize the world around you. The eyes are two in number and each is placed inside specialized compartments in the skull.

The human eye is the organ which enables you to see. The human eye does not only let you view the scenes and phenomenon in your surroundings, but also enables you to differentiate between colors. Sometimes, there is a minor defect in the eye function and the individual cannot make difference between the red and green color. What is the name for such a condition? Well, you call it ‘color blindness’.


Eyes Made of Rock Really Can See, Study Says

Mollusks' mineral lenses can distinguish shapes, not just light.

When it comes to hard stares and stony gazes, no animal can match the chiton, a small mollusk with eyes made of rock crystal. Now a new study shows just what these strange eyes are capable of.

Scientists had long known that chitons have hundreds of beadlike structures resembling eyes on the backs of their shells. The lenses "are like big, clear pieces of rock," said study leader Dan Speiser, a marine biologist at the University of California, Santa Barbara. (Related: "Coral Algae Have 'Eyes,' Study Says.")

What's been unclear, however, is if the creatures could actually see using these organs or whether the eyes were good only for sensing changes in light intensity.

"It's been known for over a hundred years that these eyes exist, but no one's really tested what sort of vision they provide," Speiser said.

His latest research—conducted while he was a graduate student at Duke University in North Carolina—revealed that the sea creatures' eyes are the first known to be made of the mineral aragonite, the same material chitons use to make their shells.

What's more, these stony eyes likely have unique advantages over the squishy eyeballs of other animals.

To test the chiton's vision, Speiser and his team collected Indian fuzzy chitons (Acanthopleura granulate) from the Caribbean.

When left alone, a chiton will lift part of its oval-shaped body to breathe. But when threatened, the animal will clamp down tightly on the seafloor to protect its soft underbelly.

In the lab, the scientists placed individual animals on a stone slab beneath a white screen, which could change colors. Once the chitons seemed relaxed, the team either placed a black disk directly above the mollusks or changed the color of the background screen from white to gray.

The black disk was designed to simulate a suddenly appearing predator, while the dimming screen mimicked subtle changes in natural light that chitons might experience in the wild—for example, when a cloud passes in front of the sun.

In the experiment, the chitons went into lockdown mode when shown the black disk, but the animals remained at ease when the screen dimmed. This suggests the chiton's eyes are able to distinguish shapes, a prerequisite for true vision.

"The eyes allow the chitons to see objects—not with much detail—but they can distinguish between approaching objects and just decreases in light," Speiser said.

Speiser estimates chiton vision is about a thousand times courser than human vision, and it's likely they see only in black-and-white. (Related: "Sharks Are Color-Blind, Retina Study Suggests.")

"Even compared to other animals with small eyes, chitons don't see particularly well," Speiser said.

Rock Eyes Better for Tidal Creatures

Chitons' rock eyes do appear to have some specific advantages. For one thing, the hard aragonite is extremely resilient, an important trait for chitons, which are constantly being pummeled by waves in their natural habitats, shallow tidal pools.

"If their eyes were made of protein"—which is the case for humans and most other animals—"they would get worn right away," Speiser said. (See "Hammerhead Sharks Have 'Human' Vision.")

For another thing, the experiments suggest aragonite allows the chitons to see equally well in air or underwater, something that's probably useful as tides ebb around the mollusks.

"Behaviorally, the chitons react the same" in both mediums, Speiser said.

That's probably because aragonite has two refractive indices, the extent to which a particular material focuses incoming light. With an aragonite eye, one index creates an image on the eye in water while the other works in air.

Meanwhile, a few mysteries remain about chiton eyes. For instance, it's still not known why only some chiton species have eyes, or how the creatures are able to use the same material to make both their eyes and their shells.

"It's going to be interesting to see how they're shaping these lenses,” Speiser said. "How do they make them the right size and shape and keep them translucent? They're exerting some very fine control."

The chiton-eyes research will be detailed in the April 26 issue of the journal Current Biology.


What are Some Common Microscopic Animals? (with pictures)

Microscopic animals are animals that are too small to be seen by the naked eye. Microorganisms such as bacteria are almost all too small to be seen without assistance, though these are not qualified as animals. Eukaryotic (complex-celled) unicellular organisms with animal-like characteristics are called protists, but these too are not considered part of Kingdom Animalia (also known as metazoa). True animals are multicellular and have differentiated tissues.

Animals that are too small to see without a microscope are the most numerous of all animals. If aliens were instructed to take a random animal from Earth, they'd probably grab some type of microscopic animal. Common ones include planarians (flatworms) many types of mites, including dust mites and spider mites and aquatic crustaceans, such as copepods and cladocerans (water fleas). The most numerous are nematodes (roundworms), rotifers (aquatic filter-feeders), and tardigrades (water bears). Nematodes, in particular, are probably the most numerous animal on Earth, representing at least 90% of all life on the sea floor, and they are ubiquitous in all habitable environments on land and sea.

Microscopic animals are part of a size continuum that stretches all the way from viruses to the largest living organisms. They were first discovered by the Dutch scientist Antonie van Leeuwenhoek, the "Father of Microbiology," in 1675, using microscopes of his own design, some of which could magnify up to 500 times. The smallest object that can be seen with the unaided human eye ranges from about 1/40 to 1 mm, but "microscopic" often refers to any animal smaller than 1 mm in width, especially smaller than 1/10 mm in width.

These tiny animals are extremely important to the global ecosystem, making up a significant portion of biomass and representing the base of some food webs. The smallest, like rotifers, mostly live on bacteria, while larger specimens consume smaller animals or suck fluids from trees. Mites are especially adapted to the latter, and are found on large numbers under the leaves of many plants. Dust mites, the most common cause of allergies, are found in nearly every human home on the planet, where they survive on dead skin cells that drop from human inhabitants. A common strategy for killing these tiny beasts is to reduce ambient moisture.

Because microscopic animals are so numerous and distributed, only a portion of them have been described by science. Others will surely be discovered in the future, adding to scientists' knowledge of the planet's biodiversity.

Michael is a longtime InfoBloom contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Michael is a longtime InfoBloom contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.


Which Animals Have YELLOW Eyes At Night?

Now let’s change the focus to animals with yellow glowing eyes for a moment. This is a very common feature among animals and we find quite a lot of species with glowing yellow eyes at night.

Bears

Bears are one example. In the daytime, they normally have dark brown eyes. But when the light reflects at night they typically appear bright yellowish.

Check out these bears staring at the driver.

They could probably scare most people if you saw them at night!

As we mentioned above, cats can have all sort of eye colors. This cat is staring at the photographer with bright yellow eyes that could pierce you.

Eye color is determined by two pigment colors called melanin and lipochrome. The blend of pigment (or lack thereof) determines which color the cat’s eyes will have. But at night time the light can change the eye color by reflecting only parts of the light spectrum.

These two sets of yellow cat eyes look pretty scary in the dark!

Deers

Another animal you typically can encounter at nighttime is the Deers. They will often stare right at you when you are driving or walking by a forest.

The eyes of the deer will often light up with a yellow tone at night simply because the light is reflected back.

Raccoons

Another animal you might have in front of you when you notice a yellow set of eyeballs is the raccoon.

Raccoons are also nocturnal animals and therefore also have the reflective layer behind the eyes. They will typically reflect yellow light back of you.

Chinchillas

Chinchillas are pretty popular as exotic pets.

Here is a cute little fella eating an apple in a tree. The yellow eyes really light up in the dark and they seem to be very focused on the photographer.

Panthers

The last animals we will look at with yellow eyes in the dark are the Panthers. They are large cats that hunt at night and their yellow eyes are very intense.

Most cats (large and small) will have yellow eyes in the dark. But most cats won’t have yellow eyes when the face is lit. But the Panthers can have very pretty yellow eyes. Though sometimes they can appear greener.


How Many Plankton?

Plankton are really important, so scientists wanted to know how many different types of microorganisms there are. Scientists captured microscopic plankton from all over the world to record the biodiversity of the little ocean critters. Then they created a huge database of all the plankton, including information on body size, genetics, and many other characteristics of each species. The huge global database is available for other scientists around the world so that they may access existing information or add new information.

Big animals like sharks and dolphins may be the easiest to recognize, but those big animals wouldn’t be able to exist without teeny tiny creatures like plankton. Maybe that’s why the Spongebob Squarepants character tries to take over Bikini Bottom. Plankton knows just how important he is to the ocean ecosystem.


Turkey Biology

Turkeys have some curious features that stand out upon first glance. One of the first things people notice about turkeys are the red, fleshy stretches of skin and bulbous growths located around the head and neck region. These structures are the:

  • Caruncles: These are fleshy bumps on the head and neck of both male and female turkeys. Sexually mature males may have large carnuncles with bright colors which are attractive to females.
  • Snood: Hanging over a turkey's beak is a long flap of flesh called the snood. During courtship, the snood enlarges and becomes red as it fills with blood in the male.
  • Wattle: These are flaps of red skin that hang from the chin. Males with large wattles are more attractive to females.

Another prominent and noticeable feature of the turkey is its plumage. Voluminous feathers cover the breast, wings, back, body and tail of the bird. Wild turkeys can have over 5,000 feathers. During courtship, males will puff up their feathers in a display to attract females. Turkeys also have what is called a beard located in the chest area. Upon sight, the beard appears to be hair, but is actually a mass of thin feathers. Beards are most commonly seen in males but may occur much less commonly in females. Male turkeys also have sharp, spike-like projections on their legs called spurs. Spurs are used for protection and defense of territory from other males. Wild turkeys can run as speed of 25 miles per hour and fly at speeds of up to 55 miles per hour.

Turkey Senses

Vision: A turkey's eyes are located on opposite sides of its head. The position of the eyes allows the animal to see two objects at once, but limits its depth perception. Turkeys have a wide field of vision and by moving their neck, they can gain a 360-degree field of view.

Hearing: Turkeys do not have external ear structures such as tissue flaps or canals to assist with hearing. They have small holes in their head located behind the eyes. Turkeys have a keen sense of hearing and can pinpoint sounds from as far as a mile away.

Touch: Turkeys are highly sensitive to touch in areas such as the beak and feet. This sensitivity is useful for obtaining and maneuvering food.

Smell and Taste: Turkeys do not have a highly developed sense of smell. The region of the brain that controls olfaction is relatively small. Their sense of taste is believed to be underdeveloped as well. They have fewer taste buds than mammals and can detect salt, sweet, acid, and bitter tastes.


4.2 View Prepared Slides

  1. Get a white slide box.
  2. Clean all of the exposed lenses with special lens paper. Do not use paper towels, Kimwipes®, or cloth as this will scratch the lenses. If the view through the microscope becomes blurred, additional cleaning with lens paper may be necessary. Use alcohol pads if necessary.
  3. Make sure that the low power objective is clicked into position.
  4. Move the oculars as far apart from each other as possible then look through them with both eyes open. You will see two non-overlapping regions of light. Push the oculars slowly towards each other until you see one circle of light.
  5. Always use both eyes when you look at slides. This will avoid eye strain and headaches.
  6. Get the slide labelled “Letter e” (Figure 4.6) from the slide box.
  7. Place the slide (coverslip up) on the stage and center the specimen over the opening in the stage.
  8. Always start with the low power (4×) objective in place.
  9. While looking through the ocular, use the coarse adjustment knob to slowly move the stage upward until the specimen comes into focus. If it does not, check to see that the material is centered on the stage, lower the stage, and try again.
  10. Using the fine adjustment knob, obtain a sharp focus.
  11. To increase the magnification, be sure the area you wish to examine specifically is in the center of the field then, watching from the side to be sure that the objective clears the slide, turn the nose-piece until the next higher power objective clicks into position. The material now should be in view and should require only slight focusing with the fine adjustment. Never focus with the coarse adjustment under high power.
  12. What happens when you increase the magnification?
  13. Before removing the slide, always return the microscope to low power and turn the coarse adjustment knob until the stage is moved all the way down.
  14. View the computer chip slide (Figure 4.7).
  15. View the colored threads slide (Figure 4.8).
  16. Which thread is at the bottom, in the middle, on top?
  17. Depth perception requires that a slightly different angle of an object is seen by the left and right eye. This happens because of the horizontal separation parallax of the eyes. If an object is far away, the disparity of that image falling on both retinas will be small. If the object is close or near, the disparity will be large. The microscope presents the same view to both eyes. Therefore, the only way to answer the above question is to change the focus of the image and observe what happens: when you move the stage upwards, to bring the slide closer to the objective, the thread that is on top will come into focus first, the middle one second and the bottom one last. Try it and write down your answer!
    • Bottom thread: __________
    • Middle thread: __________
    • Top thread: __________
  18. View the stage micrometer slide (Figure 4.9).
  19. What is the unit of this scale?
  20. What is the distance between 1.0 and 1.5 in meters?
  21. How many subdivisions can you distinguish between 0 and 0.1?
  22. What is the distance in meters between the smallest subdivision?
  23. View the blood smear slide (Figure 4.10).
  24. Which cells are red blood cells? Mark with an arrow and label it “RBC”.
  25. Which cells are white blood cells? Mark with an arrow and label it “WBC”.
  26. Return the slides to the slide boxes and the slide boxes to the bench where you picked it up.

Figure 4.6: A printed letter.

Figure 4.7: Close-up view of an electronic chip.

Figure 4.8: Which thread is on top, in the middle, at the bottom?

Figure 4.9: A microscopic scale.

Figure 4.10: A human blood smear.


Scientists identify plankton from space

This organism is a species of plankton called Mesodinium rubrum. Each is very tiny. But when they multiply rapidly, plankton can form large blooms that turn the ocean surface green, red or brown. Some blooms are so large that satellites can spy them from space.

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December 1, 2015 at 7:00 am

Plankton — tiny organisms drifting in the sea — often are too small to see without a microscope. But with the help of some math and a very powerful imaging device, scientists for the first time have identified a species of plankton from space. Finding out which plankton are proliferating can help researchers learn more about toxic threats in the ocean. For instance, it might help determine if your nearest beach should be closed owing to poisons shed by those microbes.

Plankton in the ocean often bloom — undergo short periods of rapid reproduction. The tiny organisms can increase so quickly that they form a mass big enough to change the color of the water. Affected water can turn red, brown or even green. Regardless of the color, all of these blooms are still called “red tides.”

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Some blooms can prove harmful to the environment. They can reduce the amount of sunlight that reaches other organisms. And they can deplete waters of the oxygen that fish and other species need to survive. But some blooms are particularly dangerous for people. That’s because these plankton make a toxin, or poison. Toxins can kill fish, make it hard for some people to breathe and taint the shellfish destined for dinner tables. When health officials are uncertain which species of plankton is behind a bloom, many play it safe and close beaches.

This image comes from the Hyperspectral Imager for the Coastal Ocean, which flew aboard the International Space Station. It depicts Long Island Sound, water separating New York and Connecticut. The brown smudges in the water are massive blooms of plankton — a ‘red’ tide. H. Dierssen et al/PNAS Because of red tides’ potential risks, scientists try to keep track of plankton blooms. Usually, this search takes place at sea. “We go out on a ship and take buckets of water,” explains Heidi Dierssen. She works at the University of Connecticut in Storrs. There, she studies ocean optics — the light coming off the water surface — to gauge what’s living in it.

Dierssen and her colleagues collect water samples from Long Island Sound, the water separating New York and Connecticut. It’s an estuary, where fresh and saltwater mix. Back in the lab, her team uses microscopes to scout for plankton. But because the researchers head out only once a month, they usually miss sudden blooms, even huge ones.

A lucky strike from space

But on September 24, 2012, “one of our colleagues had been out to sea, and she had seen this large bloom,” Dierssen recalls. “[She] collected some water for us and brought it back.”

At the same time, Dierssen was looking through images of the ocean captured from space. A camera aboard the International Space Station had snapped pictures of the same area of Long Island Sound — on the same day.

That camera is called the Hyperspectral Imager for the Coastal Ocean, or HICO. This spectrometer analyzes wavelengths (colors) of light. HICO was designed specifically to study light from coastal areas.

Most imagers in space “see” only about one square kilometer (0.4 square mile) per pixel. Pixels are the tiniest dots of light on a computer screen. Pictures emerge from viewing thousands of pixels or more. The smaller the area represented by each pixel, the more detailed an image will become.

This is Long Island sound, photographed using light picked up by the imager aboard the International Space Station. Yellow marks masses of certain cells performing photosynthesis. Their hue helped scientists identify which species had bloomed. H. Dierssen et al./PNAS Imagers where each pixel represents one square kilometer per pixel would portray Long Island Sound as a series of large colored blotches. The sound is only 177 kilometers (110 miles) long. Its maximum width is a mere 34 kilometers (21 miles). But HICO was almost 10 times better than those imagers. It could detect changes over areas as small as 0.00011 square kilometer (1,180 square feet) per pixel. Signs of a red ocean could be seen in this far more detailed image. The imager also could detect a wider range of colors than most similar instruments in space.

So when Dierssen studied the image from the space station, she was able to pick out the same red tide that her colleague had just sampled. “We were lucky,” she adds, because HICO “is no longer operational.” It had only been working a short time as part of a test. Another imager also captured the image, but in far less detail.

Seeing yellow, finding red

Green algae and plants possess chloroplasts (KLOR-oh-plasts). These tiny structures turn sunlight into energy. Being fluorescent, chloroplasts absorb some light, then emit a share of it back into space. Most of them emit light that the imager would read as reddish.

But one type does not. These chloroplasts contain phycoerythrin (FY-ko-eh-RITH-rin). This pigment emits light that the imager sees as yellow. HICO detected that color coming off of Long Island Sound.

Based on that yellow “flag,” Diersson and her colleagues could tell which species of plankton had made it: Mesodinium rubrum (MEZ-oh-DIN-ee-uhm RU-brum). M. rubrum is a zooplankton (ZO-plank-tun), a tiny animal that eats algae. And when it does, this animal keeps their chloroplasts, using them to get extra energy from the sun. It was the algal chloroplasts that these plankton had eaten that had emitted the yellowish glow seen from space.

Diersson’s team confirmed the animal’s ID with its microscopes. M. rubrum does not make toxins. So this red tide posed no danger to swimmers, shellfish or human diners.

The researchers also analyzed the genes — segments of DNA that are unique to each species — of the blooming plankton. These confirmed that the species was M. rubrum. The scientists published their findings November 16 in the Proceedings of the National Academy of Sciences.

“We could see the [red tide] from space,” Dierrsen says. “It’s the first time anyone’s ever done that.” While HICO is no longer working, Dierrsen hopes that future satellite sensors will allow scientists to similarly keep a spying eye out for plankton blooms.

Limitations on the technology

The new study “is a solid paper that addresses a current and topical issue,” say Leslie Brown and Gary Borstad. Both work at ASL Environmental Sciences in Victoria, British Columbia, Canada. They look for changes in the environment that can be detected from very long distances, including from space.

Brown and Borstad think it might be too risky to identify red tides solely from space. There needs to be microscopic identification of what’s causing a bloom, they explain, “especially when human health is involved.” But both agree that satellites and other space-based sensors could offer a valuable early warning of what deserves further study.

“Ships miss these big events,” Deirssen says. With spying eyes in space, “We can find out a lot about what’s growing in the ocean. It can help us find out why [plankton] bloom when they do.”

Power Words

(for more about Power Words, click here)

algae Single-celled organisms, once considered plants (they aren’t). As aquatic organisms, they grow in water. Like green plants, they depend on sunlight to make their food.

bloom (in microbiology) The rapid and largely uncontrolled growth of a species, such as algae in waterways enriched with nutrients.

brackish A term for water that contains a mixture of saltwater and freshwater.

chloroplast A tiny structure in the cells of green algae and green plants that contain chlorophyll and creates glucose through photosynthesis.

environment The sum of all of the things that exist around some organism or the process and the condition those things create for that organism or process. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature, humidity and placement of components in some electronics system or product.

estuary The mouth of a large river, where it empties into the ocean and freshwater and saltwater mix. Such regions are often nurseries for young fish.

fluorescent Capable of absorbing and reemitting light. That reemitted light is known as a fluorescence.

gene (adj. genetic) A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

International Space Station An artificial satellite that orbits Earth. Run by the United States and Russia, this station provides a research laboratory from which scientists can conduct experiments in biology, physics and astronomy — and make observations of Earth.

microbe Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.

microscope An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.

NASA See National Aeronautics and Space Administration

National Aeronautics and Space Administration Created in 1958, this U.S. agency has become a leader in space research and in stimulating public interest in space exploration. It was through NASA that the United States sent people into orbit and ultimately to the moon. It has also sent research craft to study planets and other celestial objects in our solar system.

optics Having to do with vision or what can be seen.

organism Any living thing, from elephants and plants to bacteria and other types of single-celled life.

oxygen A gas that makes up about 21 percent of the atmosphere. All animals and many microorganisms need oxygen to fuel their metabolism.

photosynthesis (verb: photosynthesize) The process by which green plants and some other organisms use sunlight to produce foods from carbon dioxide and water.

phycoerythrin A protein that can harvest light energy from the sun. It is found in red algae.

phytoplankton Sometimes referred to as microalgae, these are microscopic plants and plant-like organisms that live in the ocean. Most float and reside in regions where sunlight filters down. Much like land-based plants, these organisms contain chlorophyll. They also require sunlight to live and grow. Phytoplankton serve as a base of the oceanic food web.

pixel Short for picture element. A tiny area of illumination on a computer screen, or a dot on a printed page, usually placed in an array to form a digital image. Photographs are made of thousands of pixels, each of different brightness and color, and each too small to be seen unless the image is magnified.

plankton Small organisms that drift or float in the sea. Depending on the species, plankton range from microscopic sizes to organisms about the size of a flea. Some are tiny animals. Others are plantlike organisms. Although individual plankton are very small, they form massive colonies, numbering in the billions. The largest animal in the world, the blue whale, lives on plankton.

Proceedings of the National Academy of Sciences A prestigious journal publishing original scientific research, begun in 1914. The journal’s content spans the biological, physical, and social sciences. Each of the more than 3,000 papers published each year, now, not only is peer reviewed but also approved by a member of the U.S. National Academy of Sciences.

red tide A population explosion of certain species of plankton. When enough are present, they can color the water red or reddish-brown. Some secrete a poison that can kill surrounding fish and make people sick.

satellite A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.

species A group of similar organisms capable of producing offspring that can survive and reproduce.

spectrometer An instrument that measures a spectrum, such as light, energy, or atomic mass. Typically, chemists use these instruments to measure and report the wavelengths of light that it observes. The collection of data using this instrument, a process is known as spectrometry, can help identify the elements or molecules present in an unknown sample.

toxin A poison produced by living organisms, such as germs, bees, spiders, poison ivy and snakes.

wavelength The distance between one peak and the next in a series of waves, or the distance between one trough and the next. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.

zooplankton Small organisms that drift in the sea. Zooplankton are tiny animals that eat other plankton. They also serve as an important food source for other marine creatures.

Citations

A. Pearce Stevens. “Tiny plastic, big problem.” Science News for Students. April 10, 2015.

A. Pearce Stevens. “Corals dine on microplastics.” Science News for Students. March 18, 2015.

B. Brookshire. “Scientists Say: Plankter.” Eureka! Lab. February 2, 2015.

S. Zielinski. “Will water woes leave Americans thirsty?” Science News for Students. October 30, 2014.

C. LeBlanc. “Suffocating waters.” Science News for Students. March 29, 2012.

S. Ornes. “The algae invasion.” Science News for Students. May 11, 2010.

R. Ehrenberg. “Blooming jellies.” Science News for Students. April 9, 2008.

E. Sohn. “Deep krill.” Science News for Students. March 5, 2008.

Original Journal Source: H. Dierssen et al. Space station image captures a red tide ciliate bloom at high spectral and spatial resolution. Proceedings of the National Academy of Sciences. Published online November 16, 2015. doi: 10.1073/pnas.1512538112.

About Bethany Brookshire

Bethany Brookshire was a longtime staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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4.1 Elodea Leaf Wet Mount

Elodea canadensis (American or Canadian waterweed or pondweed) is a perennial aquatic plant, or submergent macrophyte, native to most of North America. It grows rapidly in favorable conditions and can choke shallow ponds, canals, and the margins of some slow-flowing rivers. It requires summer water temperatures of 10-25 °C and moderate to bright lighting. Young plants initially start with a seedling stem with roots growing in mud at the bottom of the water further adventitious roots are produced at intervals along the stem, which may hang free in the water or anchor into the bottom. It grows indefinitely at the stem tips, and single specimens may reach lengths of 3 m or more. The leaves are bright green, translucent, oblong, 6-17 mm long and 1-4 mm broad, borne in whorls of three (rarely two or four) round the stem. It lives entirely underwater, the only exception being the small white or pale purple flowers which float at the surface and are attached to the plant by delicate stalks. It is dioecious, with male and female flowers on different plants. The flowers have three small white petals male flowers have 4.5-5 mm petals and nine stamens, female flowers have 2-3 mm petals and three fused carpels. The fruit is an ovoid capsule, about 6 mm long containing several seeds that ripen underwater. The seeds are 4-5 mm long, fusiform, glabrous (round), and narrowly cylindrical. It flowers from May to October.

4.1.1 Experimental procedures

  1. Get a single leaf from the Elodea plant and mount it on a slide, cover it with a drop of water and a cover slip.
  2. Place the slide onto the microscope state and observe at the leaf under the microscope.
  3. These leaves are two cells thick, so you should be able to focus up and down to see that the cells in one layer are larger than those in the other. When one layer is in focus, you may be able to see the shadowy outlines of cell walls in the other layer.
  4. Notice that the cells are clearly delineated by the cell wall.
  5. Inside the cells are large oval-shaped green bodies, the chloroplasts.
  6. As the cells warm, you can see the chloroplasts carried by the moving cytoplasm around the nearly transparent nucleus in the center of the cell.
  7. Make a drawing of what you see at 400× magnification.

Figure 4.6: Elodea leaf wet mount (4× objective).

Now, please watch the following video and see how it compares to what you have just read:


Watch the video: Planck Length - Sixty Symbols (January 2022).