Exploration of the Pond
This gallery is an exploration of the microscopic flora and fauna found in fresh water habitats.
Population Explosion of Flagellates
Configured for darkfield polarised light, here we image a population explosion of flagellated micro-organisms.
Just like the stream lines seen in vortex shedding from the wing tips of an airplane as it passes through moist air, in the second half of this movie clouds of flagellated protozoa make visible the twin vortex generated by a rotifers ciliated 'turbine'. By reducing the exposure time the tracks of the particles can be traced out, just like when one photographs the trailing lights of the traffic in a long exposure at night.
Peritrich Colony in Darkfield (DF)
Large colony of the bell shaped ciliate - Peritrich. The entire colony is attached by a single long slender stalk to the organic debris below. Peritrich are holozoic ciliates. This means that they have a mouth and acquire nutrients by engulfing solid organic matter. Their mouth consists of an elaborate food-catching apparatus that secures food by means of ciliary currents. The anterior end of each peritrich body forms a bulging peristome. The peristome is the blue coloured path seen in each cell and is defined as a fringe of small projections around the mouth of a capsule. In this case, the fringe is composed of cilia, all of which beat in synchronised motion, like a Mexican-wave. The motion induces a water currents in the local environment in the form of a vortex that causes food particles to spiral down the funnel where they are then guided into the vestibule along the adornal zone.
Peritrich Colony in DIC+DF
Close-up of a large colony of the bell shaped ciliate - peritrich. The colony mirrors the structure of a tree in that it has a trunk called a stalk made up of myonemes. The stalk breaks up into a series of branches at the end of each is the bell-shaped peritrich capsule.
The blue coloured path is the peristome, the structure that generates the beautiful instability in the local watery environment, the vortex that funnels food into its mouth.
Starting at a magnification of around 100 times, the movie shows the scene from the above photos - the overall tree-like structure of a colony of Peritrich microorganisms. The movie then progresses to a higher magnification at over 200 times to examine the finer details of the organisms. You can see the 'turbine' spinning at the anterior end of the vestibule. In fact, this is not a turbine but a row of hair-like structures called cilia. The cilia beat back and forth in a synchronised motion which gives the impression of rotation. Returning to x100 we see the spring like reflexes of the peritrich stalk that anchors the colony to a substrate composed of organic debris. Next we transition to over 400 times magnification switching from dark field to differential interference contrast microscopy that gives a 3D like effect.
The movie shows a swarming population of dinoflagellates collected from a bloom in a fresh water habitat. The movie shows sequential magnification of approximately 150 to 250 times imaged in DIC.
A rootlet of pond weed provides the basis for a micro-ecosytem. Here we see Paramecium feeding on biofilms that encapsulate the rootlet.
Belonging to the kingdom Protista, Paramecium are agile creatures whose hydrodynamic propulsion in the low Reynolds number regime is achieved by rapid synchronised beating of the thousands of cilia carpeting its outer body.
Here, a Paramecium bursaria glides along a filament of alga hoovering bacteria that populate the encapsulating biofilm.
The intake of food is achieved by the beating cilia lining its oral groove, which induce a circular rotating vortex in the surrounding local environment and thereby funnel small debris into its mouth. The food particles are stored in membrane bound compartments called vacuoles which breakdown the food through chemical reactions catalysed by enzymes.
Paramecium feed on the biofilm encapsulating a strand of filamentous Spirogyra algae. The cell nuclei and cytoskeletal network are visible in the filamentous algal cells. The globular spots on the cytoskeletal filaments are motor proteins which ‘run’ along these microtubule ‘highways’. The green structures are the chloroplasts which are helically wound within the interior of the cells and produce sugary food and oxygen as a waste product through photosynthesis.
Cyclosis in Canadian Pond Weed Elodea canadensis
Cytoplasmic streaming in the cells of Elodea canadensis (Canadian pondweed). You can see the diffraction spots of motor proteins pushing and tugging on the chloroplasts as the run along the cytoskeletal filaments.
Timelapse movie show the movement of blue-green algae. The locomotion of this algae is thought to result from the secretion of mucus slime...