A pond is a body of freshwater smaller than a lake. Ponds are naturally formed by a depression in the ground filling and retaining water. Streams or spring water is usually fed into these bodies. They can also be man-made ponds which can be created by damming a stream, digging a hole. Ponds are usually land locked and have no outflow. Because of this, they are considered to be self-contained ecosystems. These ecosystems are often teeming with rich vegetation and a diverse organismal life.
A drop of pond water appears clear and lifeless to the naked eye but within it are many queer creatures that can only be seen when viewed through a high-powered microscope. The first simple microscopes, magnifying ten times or less, were made by Dutch spectacle-makers in the 16th century. These aroused a great deal of wonder and it was considered particularly fascinating to watch live fleas with them. Thus they became known as "flea glasses". By 1674, the self-taught Dutch naturalist and lens-grinder, Leeuwenhoek, had made microscopes giving magnifications up to 270-power and had begun to tell about the multitude of very small living things he saw in water.
A whole new world of life was revealed for the first time. Since then, thousands of species of microscopic water plants and animals have been described and given scientific names. Common English names are rare. They can multiply at an enormous rate and are the most abundant living things in both fresh and salt water. A single quart of water may have more individuals in it than there are people in the world. Life in a Drop of Pond Water, students observe microscopic organisms found in pond water using a hand lens, 10x magnification, and 40x magnification. Observing these organisms should stimulate discussions about how single-celled living things might satisfy their needs for food, water, and air.
They can do this by comparing the needs of macroscopic organisms to those of microscopic ones. It is important to remember that while watching microorganisms is informative, it is not always likely that students will be able to observe these tiny cells performing such functions as dividing or taking in food. Thus direct observation should be supplemented with films of living cells or by using prepared materials.
If we look carefully and examine pond water without culturing it, we will probably find the protozoa are somewhat difficult to find because they are not present at high density. To increase the protozoa density, we will make a hay infusion .A hay infusion is a culture made from water collected from a pond, lake, stream, or puddle. In making this First, we must go to our nearest body of water and collect a water sample. Any natural water will work, but tap water out of our tap will have enough chlorine in it to kill or inhibit the growth of microbes.
Pour the water into the Gatorade battle , and add a handful of hay or grass to the pound water. A bottle we do not care about should be used, as it is going to get pretty scummy. Let the mixture incubate at room temperature or above for several days. If desired, the addition of a light source will encourage the growth of photosynthetic microbes. During the incubation, check the infusion and add more pond water as it evaporates. In 5 to 10 days the broth should turn dark and turbid. Examination under a microscope will reveal a large number of microorganisms. Lay two or three strands of cotton on a microscope slide.
Apply a drop of pond water to the cotton strand by means of dropper using wet mount technique. Place a cover slip over the drop of water. Place the slide on the microscope stage and observe the drop of water under LPO. Gradually shift to HPO. And then record the observations. Differentiate non-living object from the living organism we see in the water sample .Sketch the structure of each living organism we see in the microscope and write a short description on the organism’s color, shape, movement, and relative size. Lastly, place a drop of salt solution at the right edge of the glass slide and observe the behaviour and direction of movement of the organism.
Result and discussion
One of the better known creatures, one that often swarms in puddles and ponds, is the Paramecium or Slipper Animalcule which is barely visible to the naked eye. It moves using tiny hair-like structures on its surface called cilia. In fact, the paramecium belongs to a whole group of protists that move using cilia, the Phylum Ciliophora. Compared to the amoeba, the paramecium is fast swimmer. It is so fast that when looking for it under the microscope it may zoom right over your viewing field before you have a chance to really even see it. For this reason, biologists add a thickening agent to the water to slow the paramecium down so it can be seen more clearly. You can also place obstacles on the slide to get in its way, such as cotton fibers. Once you have the paramecium slowed or trapped, you can see many amazing features within it. The paramecium has two nuclei.
One nucleus controls the cells activities, and the other functions in sexual reproduction. As the paramecium swims forward, it will roll its body so you can see both sides. On one side is an indentation called the oral grove. The paramecium sweeps food into this opening, which then forms a food vacuole within the cell where digestion occurs. Like the amoeba, paramecium generally eat protists that are smaller than they are. The oral groove is also used in sexual reproduction, where two paramecia join together and exchange DNA. Once they separate and divide by mitosis, the new paramecia are different from the original parent. Both the amoeba and the paramecium live in fresh water, and due to osmosis, water will tend to enter their cells. These two protists must have a strategy for removing the excess water (or they might explode!).
The organelle called the contractile vacuole does the job. It serves as a water pump to remove the extra water that builds up in the cell. Under the microscope, the contractile vacuole will often look like a clear air bubble within the cell. The amoeba and paramecium are just two of the many protozoa you can find living in pond water. There are other groups like the Zoomastigina phylum which include protists that move using a tail like structure called a flagella. The euglena has a flagella, but it is sometimes classified as an algae because it can photosynthesize use light to create food like a plant.
Seen under a microscope, its body is a single cell enclosed in an oblong flexible envelope covered by thousands of short hair-like "cilia" that actively row the animal about. And they are moving fast and freely without the stand of cotton but when we put some cotton on it we can see under the microscope that the organism got trap and cannot move anymore. If we add salts to the water to match the solute concentration inside the Paramecium, this balances the osmotic pressure and the contractile vacuole can go take a nap or something because water is no longer entering the cell.
