LAKE BIWA MUSEUM

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July 16, 2008

Microscopic World

Lake Biwa Museum opens workshop for students. The students go out to the lake just out side of the museum to collect planktons. They are hardly seen by eyes, so students use the electron microscopes to watch and draw each of them in the laboratory. Several sample photos of planktons are prepared by the museum curators. So students can recognize what they are actually watching through the microscopes. At the end, the museum curators explain each of phytoplankton and zooplanktons.

Today, many of the students collected anabaena and microcystis. They are genus of filamentous cyanobacteria. The cities and villages have been rapidly developped and nutritious drain flow into rivers and lakes. That propagates cyanobacteria and float surface of the lake which looks like dropping green ink on water. The cyanobacteria produce neurotoxins, which is toxic and harmful to environment, plants and animals.

The plankton shown in the TV monitor is Noro (Leptodora kindtii), a kind of water flea. It looks like a tiny shrimp, which has single compound eye.

The curator Taisuke Otsuka is the specialist of phytoplankton. Phytoplankton doesn’t move by itself, so it is not easy for students to find. He shows the features of the planktons and explains its' ecology.

What is Plankton anyway?

Plankton is defined as a creature which has limited ability to move by itself or just float in the water.

So the 1/1000 millimetre long Picoplankton is a plankton, and 2 meters long Megaplankton such as jellyfish is a plankton as well.

Is the Slipper Animalcule male or female?

It is said that there are more than several thousands different kinds of plankton only in Lake Biwa. However, only about 800 of those have been listed up. Plankton can be normally divided in two groups. Phytoplankton and Zooplankton. To get nutrition, phytoplankton photosynthesizes and zooplankton feeds on other plankton. Each of them has different size in different colour.

One is in pink to protect itself from sunshine, and another is in red dyed by food. Some stick sand grains to create nest, and another has mucus around its body to protect from predator.

Paramecium, Slipper Animalcule has 3 genders A, B, and C!! unlike most of the beings on the earth which have two genders, male and female.

Super Unicellular It is thought that life on earth began 3 billion years ago. It is still unknown what exactly the first being emerged was. It is commonly understood that the first being produced its offspring which produced its' offspring, and gradually increased variation between organisms, then each of them branched out to millions of species. There are many different kinds of microscopic organisms which evolved in the different way from human, mammalians, fowl, fish and so on. They are unicellular, which consist of only one cell. Their sensory system is not divided into mouth, nose, eye, ear, and so on. But unicellular has ability to sense. One proceeds towards light, another recognizes smell and another feels magnetism. "Unicellular is like a computer chip. One cell has all functions of the sensory systems. It is likely to be misunderstood that unicellular have fewer abilities, but that is wrong", said Yasushi Kusuoka, the Senior Research Scientist.

Gallery C exhibits the culture and life style of the people around the Lake Biwa. The plankton zone in the gallery was expanded in March 2008 after renovation.

Actually some unicellular plankton has amazing ability. For example, one amoeba never die. If the cell is damaged or lost part of it, it can fix the damage by itself. It reproduces via mitosis and cytokinesis. When it becomes old, the amoeba can be merged with younger one to be a younger unicellular. Paramecium bursaria, a kind of slipper animalcule, can survive only with sun shine. Paramecium bursaria has symbiotic algae, chlorella. Paramecium bursaria feeds on organic substance which is produced by chlorella via photosynthesis. The chlorella feeds on phosphorus and nitrogen which is excretions of the Paramecium bursaria.

The senior research scientist Kusuoka released his discovery of the new kind of ciliophora, which is a kind of the slipper animalcule. The ciliophora was collected from the lake shore close to the museum. Kusuoka studied the ciliophora with Prof. Dr. Wilhelm Foissner from University of Salzburg and Associate Professor Tomoyuki Nagano from Miyagi University of Education and they have determined that it is a new species. His dissertation was published on International Society of Protistologists' scientific journal, "Journal of Eukaryotic Microbiology" in June. The ciliophora was named Levicoleps biwae by Dr. Foissner. Levi means "smooth" and Biwae means "Lake Biwa". Lake Biwa has long history. It is thought that Levicoleps biwae was emerged in the ancient times. It may have some clues to find out about specialisation in the ancient lake.

Plankton supports a lot of lives in water. When you take a look at lakes, liver or ocean, plankton is too tiny for our naked eyes. If you get interested in the micro world, you would find that there is a huge wonder world.

The planktons in the illustrations are depicted to show you the detail and not in the right size or ratio.

(December 12, 2007) 

Lake Biwa is located at the centre of the main island, Honshu, in Japan. The biggest freshwater lake in Japan has unique biological environment. Some species are indigenous to Lake Biwa.

Lake Biwa Museum is located on the Karasumaru Peninsula, which is at the southeast edge of the Lake Biwa. The museum has three galleries and an aquarium. Through the three galleries, the visitors can experience the history of Lake Biwa from the ancient era, which is about 4 million years ago, to the present time. At the aquarium, you can see many rare freshwater fish and bugs living in Lake Biwa.

Why is the fossil of elephant here?

Lake Biwa is moving.

4 million years ago, Lake Ohyamada was formed at the area currently Ueno valley in Mie Prefecture. The Lake Ohyamada, also called Old Lake Biwa, gradually moved to north, and reached to the current location 400 thousand years ago. Believe or not, the lake is still moving to north. Probably it will reach to the Japan Sea in the future. Gallery A shows geological history. You see the gigantic elephant fossil at the centre of the hall. The fossil is big enough for visitors to walk under its belly. This is the Yellow River Elephant's fossil found in China. It is said that the Yellow River Elephant had been small sized and become the ancestor of the Akebono Elephant, Stegondon aurorae. The Akebono Elephant lived in Japan between 2.5 to 1 million years ago. Its fossil has been found from the Lake Biwa area. The gallery exhibits other fossils from the era of Old Biwa Lake such as fish, shells and plants. You are allowed to touch the fossils of dinosaur's droppings, shark’s teeth, and more. "Wow, it stinks!!" Some kids blows ups his imagination from the dinosaurs' droppings. According to a guide, many children get surprised by the sharp shark's teeth.

Tiny Endangered Species

Biwatsubokamuri, Difflugia biwae, is a very rare plankton. Despite the lake water is cleaner now than it was in 1980s, the plankton has not seen since 1981. Nobody knows why it disappeared. In the Gallery C, you can see planktons through a microscope. The fresh plankton is collected from the lake every morning, so you can see it moving actively. Here is an interesting display about dobu. Dobu is swampy place that looks muddy and dirty, but actually full of small lives, plants and algae. The display of enlarged models shows you the eco system of the micro world in dobu liver. There are crayfish, water boatmans and their food such as grain of rice from through drain. Mr. Yasushi Kusuoka, the Senior Research Scientist, made this display. He says, "Sometimes the ideal environment for a living thing is dirty smelly place for human. Each live has its own suitable condition to live and it's different from others. That is one of the themes that the museum wants the visitors to think about. The display here encourages the visitors to aware what the good environment really is more carefully."

Big catfish look like sumo wrestlers.

The must see featured fish is the Lake Biwa Catfish. Take a closer look! The huge catfish dwell in the dome tank will amaze you. Two of these catfish are very territorial and wrestle with each other sometimes. Another interesting fish is ginbuna, gibelio, a kind of carassius. The female fish can produce their offspring without a male. Gigi the catfish is also unique. She makes noise sound like "gi. gi. gi. gi. gi……"

Don't be afraid. Hold the crayfish on your hand.

Ms. Mako Kondo is a guide attending at "Touching Pool". She observes many children reacting differently from the slimy Nigoro-Carassius. Some kids are afraid of the big nails of crayfish. When she finds kids with full of curiosity, she put a crayfish on their hands. That must be an exciting experience for children. "It is my pleasure to support children to feel and touch the little wild creatures", she says.

Are you loosing weight?

The American Paddlefish and the Garpike have been existed since ancient era. The fish keeper Mr. Takashi Okada feeds these living fossils here. They eat powdered food in the aquarium. "They are so sensitive. Sometimes I notice that some of them loose their weight and hard to tell why," says Mr. Okada. The American Paddlefish opens his big mouth to eat plankton in the wild. The Sturgeon has its mouth at the bottom of his face and eat clams and warms by digging up mud. Let's observe the different shapes and behaviours of fish.

Lake Biwa for the local people

You'll learn the local people's culture and history by the lake. The traditional cargo boats and houses are on display.

Barrel Bath

Wooden Barrel Bath looks like a historical item, but it is still used by a local family.

"All species are interdependent". Lake Biwa has about 50 different kinds of fish and 15 of them are the indigenous. The population is decreasing because of alien fish such as the Blue Gill and the Black Bass. Global warming is considered as another reason. The museum research team studies about endangered species at the conservation centre.

Let's ask!

In the museum, there are several field of the researchers such as ecologist, biologist, physicist, and so on. Those researchers give some lectures to visitors. Not only that, there are some guides working to show you more about display and answer your questions in the museum.