1. Pond Life Jar
Click on the organism in the jar, then click on the organism again to return to the jar

3. Euglena (single-celled)
Name (genus): Euglena
Size : µm
Where to find them : Planktonic, often colouring the water green.
Notes : Euglena, like some other micro-organisms, have features of both algae (e.g. green and photosynthesise) and protozoa (moves with whip-like flagella). Thus biologists debate how they should be classified. It also has a red eye spot.
You may come across them when viewing a larger organism under the microscope. Euglena, if abundant, may cross the field of view moving in and out of focus.
Classification :
Kingdom - Protoctista, Phylum - Discomitochondria

4. Spirogyra (single-celled)
(Example of a filamentous algae)
Name (genus): Spirogyra
Size : Filaments µm wide, filaments up to many cms long
Where to find them : Often occurs in floating green masses, slimy to the touch.
Notes : The single cells are arranged end to end to form long threads (filaments). The spirally arranged ribbon-like plastids are distinctive. Many biology textbooks use this as the example of a filamentous algae.
Classification :
Kingdom - Protoctista, Phylum - Gamophyta

5. Actinosphaerium (single-celled) (Example of a heliozoa)
Name (genus) : Actinosphaerium
Size : µm
Where to find them : Planktonic and amongst plants (especially fine-leaved).
Notes : The Heliozoans, also called sun-animalcules in older books, are a delight to study under the microscope. They have hair-like pseudopodia called axopodia (which are often stiffened) that radiate outwards.
There are a number of smaller species e.g. in the genera Actinophrys and Acanthocystis.
Classification :
Kingdom - Protoctista, Class - Heliozoa

6. Hydra (multicellular)
Name (genus): Hydra
Size : mm including tentacles
Where to find them : Attached to surfaces like water plant stems and the undersides of floating leaves.
Notes : The Hydra is a very distinctive creature with its tentacles. If a jar of pond water with some weed is left to stand for a while, the hydra - if present, may be seen by eye attached to the wall of the jar, or the vegetation. They are often pale brown or green. The underside of floating weed like duckweed is a particularly good place to find them.
Hydra have many fascinating features, one in particular is that they can reproduce asexually by budding where a smaller hydra grows off the body of the adult and eventually separates. The tentacles have stinging cells which they use to capture prey like small water fleas. They are a classic organism for biology students to study as they are a representative member of the Phylum Cnidaria. The cnidarians are the most primitive animal where the cells are organised into different layers.
Classification :
Kingdom - Animalia, Phylum - Cnidaria, class - Hydrozoa

7. Daphnia (multicellular)
(Example of a water flea)
Name (genus): Daphnia
Size : mm
Where to find them : Planktonic, or amongst plants, organic matter etc.
Notes : Water fleas are a delight to observe under the microscope. The beating heart, compound eye and moving limbs can all be seen as they have a transparent shell. The water flea shown is the well known genus Daphnia which are often available in pet shops for fish food.
Another common water flea Simocephalus is similar but usually larger. Chydorus, is another common one, but smaller and more globular, and often found amongst weeds.
Water fleas are easy to spot in a jar of pond water by the jerky movements of their second antennae (shown left). Hence their common name, although they are not fleas.
The females often carry live young, and if you are lucky they may give birth while you are examining them.
Classification :
Kingdom - Animalia, Phylum - Crustacea, Order - Cladocera
Note: The classification where Crustacea is assigned a phylum is adopted here.

8. Stentor (single-celled)
Name (genus): Stentor
Size : Up to mm long
Where to find them : Attached to plants/algae and planktonic.
Notes : One of the largest freshwater protozoans and larger than some multi-celled pond animals.
When it is attached to a surface, it adopts the trumpet shape shown and the ring of cilia around the trumpet rim draw in water, together with the smaller organisms on which the Stentor feed. When the Stentor swims it adopts an oval shape.
The Stentor is often green in colour because of the algae (single-celled plants) associated with it. Like other large single celled creatures (e.g. amoebas) they have many nuclei. In Stentor you can see the nuclei as a 'string of pearls'. The large sphere is a water expelling vesicle. The cell is covered with tiny hair-like 'cilia'.
Classification :
Kingdom Protoctista, Phylum Ciliophora

9. Paramecium (single-celled)
Name (genus) : Paramecium
Size : µm
Where to find them : Plankton and amongst organic matter.
Notes : One of the larger singe-celled pond animals. Many protozoa are very small, but the larger Paramecium can just be seen as a speck swimming in pond water. A compound microscope at 40X - 100X should show more detail if you can catch one with an eye dropper and place it on a slide.
The older text books called them 'slipper animalcules' as with careful study under a microscope they do look like a slipper. The Paramecium is often used as one of the classic examples of a protozoan and are widely illustrated in biology textbooks.
Classification :
Kingdom Protoctista, Phylum Ciliophora

10. Vorticella (single-celled)
(Example of a peritrich)
Name (genus) : Vorticella
Size : The 'bell' is up to 150 µm, with stalk up to 1 mm.
Where to find them : Attached to algae and plants etc.
Notes : Vorticella are one of the peritrich protozoa. Although solitary, they often occur in groups to form a tiny jelly-like mass just visible to the naked eye. Their stalks contract like a spring. Some similar types e.g. Epistylis (not contractile) and Carchesium (contractile) are true colonies with branching tree-like stalks.
Classification :
Kingdom Protoctista, Phylum Ciliophora

11. Desmid (single-celled)
Example - genus Closterium
Name : Desmids
Size : Wide range amongst species
ca 10 µm - 1 mm
Where to find them : Planktonic, or on vegetation, particularly neutral to acidic waters.
Notes : An attractive and varied group of algae. Although species vary widely in shape, they share the feature of being divided into two equal halves (semicells) which are often mirror images. A distinct constriction between the two semicells or gap in the plastids is usually seen.
Classification :
Kingdom - Protoctista, Phylum - Gamophyta

12. Volvox (single-celled, but colonial) Name (genus) : Volvox
Size : Colonies up to 1 mm
Where to find them : Planktonic in still and flowing waters.
Notes : One of the 'jewels' of a pond when found. Volvox is a spherical colony of hundreds of green algal cells each with two whip-like flagella. These cells are distributed on the surface of a hollow jelly-like globe. Sometimes the colony may contain smaller colonies as shown left.
Volvox has features of both algae and protozoa, and is classified by some authorities as a green algae (Chlorophyta) and by others in the protozoan order Volvocida.
Classification :
Kingdom - Protoctista, Phylum - Chlorophyta

13. Rotifers (multicellular)
Examples of genera left to right below:
Philodina, Collotheca, Brachionus
Name (phylum): Rotifers
Size : Wide range amongst species
25 µm - 1 mm
Where to find them : Some species are planktonic, others are attached to plants, other organisms, stones or creeping on plants, mud surface etc.
Notes : A particularly fascinating group for the pond dipper with a microscope. Older books call them wheel animalcules. The head has a crown of cilia (the 'wheel organ'), which in some species looks as if it is rotating like a wheel, hence their common name.
Rotifer species show a wonderful variety of forms. Some move and contract like a leech (e.g. Philodina far left), others build 'houses'.
Classification :
Kingdom - Animalia, Phylum - Rotifera

14. Cyclops (multicellular)
Name (genus): Cyclops
Size : mm
Where to find them : Planktonic, or amongst plants, organic matter etc.
Notes : Cyclops is one of the easiest pond creatures to see and identify even with the naked eye. The female often carries a pair of egg sacs and is a fast swimmer! It possesses just one eye hence it was named after the Greek mythological creature of this name.
They are usually a drab green or brown but can be quite brightly coloured. Another common copepod Diaptomus has one egg sac, longer antennae, and long thin body.
Classification :
Kingdom - Animalia, Phylum - Crustacea, Class - Copepoda
(Example of a copepod)

15. Cypris (multicellular)
(Example of an ostracod)
Name (genus): Cypris
Size : mm
Where to find them : Amongst aquatic vegetation and browsing the surface layers of bottom mud
Notes : The body of an ostracod, including the head, is enclosed by a bean-shaped shell (the carapace). If seen at low power under the microscope, just the antennae and limbs appear out of the gap between the two halves of the shell as they move amongst vegetation and mud.
Some of the smaller rounded water fleas (e.g. Chydorus) may be confused for an ostracod, but the shell of a water flea is usually much more transparent.
The ostracods, although quite easy to recognize, are often hard to identify further, because externally they all look rather alike!
Classification :
Kingdom - Animalia, Phylum - Crustacea, Class - Ostracoda

16. Diatoms (single-celled)
Name (phylum): Diatoms
Size : wide range amongst species
ca µm
Where to find them : Planktonic, or attached to plants; often form brown crusts on surfaces under water e.g. stones, plant stems.
Notes : Diatoms have silica shells in two halves that fit together like an old pill-box. The shell (the frustule) often has very fine structure (which is best seen in commercially prepared slides of diatoms). The optical microscope is pushed to the limit to resolve the detail in some species.
Classification :
Kingdom - Protoctista, Phylum - Diatoms (Bacillariophyta)

17. Pond Life JarAmoeba (single-celled)
Name (genus) : Amoeba
Size : µm
Where to find them : Decaying organic matter e.g. on leaves and surface of bottom mud.
Notes : Although usually common, they're not always abundant, so casual pond dipping may not find them. Inspect samples from the habitats above carefully in a Petri dish with low power first, to locate specimens for study at higher powers. The finger-like protusions (pseudopodia) are used for movement and feeding.
The amoeba shown is a so-called naked amoeba. There are also testate amoeba which live in shells (tests). Squeezings from Sphagnum moss may often contain examples of testate amoeba.
The species Amoeba proteus, although apparently rare in the wild (see ref. 4), is often cultured for classroom studies of a protozoan. Amoeba are widely described and illustrated in biology textbooks.
Classification :
Kingdom Protoctista, Phylum Rhizopoda