Common Phytoplankton and Zooplankton in Carroll County Ponds

Some Examples

Phytoplankton

Kingdom Monera – The Blue-green “Algae”

Nostoc sp.

• Forms colonies composed of filaments of moniliform cells in a gelatinous sheath

• Possess heterocysts (clear, thick-walled cells) capable of nitrogen fixation

Phytoplankton

Kingdom Monera – The Blue-green “Algae”

Lyngbya sp.

• Filaments lack heterocysts

• Filaments with equal diameter throughout whole length

• Rigid sheath that can extend beyond the cells in the filament

Phytoplankton

Kingdom Monera – The Blue-green “Algae”

Merismopedia sp.

• Cells arranged in perpendicular rows one cell thick to form rectangular colonies

• The colonies may be flat or slightly wavy and are held together by colorless, indistinct mucilage

Phytoplankton

Division Chlorophyta – Green Algae

Botryococcus sp.

• Cells form an irregularly shaped aggregates, with thin filaments connecting cells.

• Will bloom when in the presence of elevated levels of dissolved inorganic phosphorus

• Has potential as a producer of biofuels

Phytoplankton

Division Chlorophyta – Green Algae

Scenedesmus sp.

• Colonies with 4, 8, or 16 cells arranged in a row.

• Spines and bristles make the colonies more buoyant and allow them to uptake the light and nutrients that are more abundant near the surface, and may deter predation by herbivores

• May be dense in nutrient- rich waters

Ankistrodesmus sp.

• Cells are long and needle- or spindle-shaped, or sometimes curved or slightly crescent-shaped.

• May be found individually, clustered, twisted around each other, or in tufts among other algae.

• The parietal chloroplasts sometimes have pyrenoids

Phytoplankton

Division Chlorophyta – Green Algae

Staurastrum sp.

• Cells composed of two halves (semicells), often almost divided from each other by deep median incisions (True of all desmids)

• Often bear elaborate ornamentation

• Many small processes and arms tipped with spines

Phytoplankton

Division Chlorophyta – A Desmid

Fragilaria sp.

• Frustules rectangular to lanceolate, in girdle view

• Frustules are joined by small marginal spines to form ribbon like (band-shaped) colonies.

Phytoplankton

Division Bacillariophyta – Diatoms

Dinobryon sp.

• Loricate

• Lorica cylindrical and consisting primarily or entirely of cellulose and protein; vase- or Funnel-shaped and often with a slightly broadened mouth

• Forming arbusculate (tree-like) colonies (rarely solitary)

Phytoplankton

Division Chrysophyta – The Golden Algae

Phytoplankton

Division Pyrrophyta – Dinoflagellates

Peridinium sp.

• Motile, single, golden-brown cells

• Outer covering of rigid plates

• Two flagella

Phytoplankton

Division Rhodophyta – Red Algae

Porphyridinium sp.

• Cell with pink to red chloroplasts

• Cells solitary, but often grouped into irregular colonies with ill-defined mucilaginous matrix.

• Forms gelatinous coatings on surfaces in freshwaters

Zooplankton

Kingdom Protista – Protozoans, Ciliates

Prorodon sp.

• Flexible ovoid body, round in cross-section

• Mouth apical

• Swims in large circles, revolving rapidly around the long axis of its body.

• Eats bacteria, green algae, and small nematodes. Cytoplasm typically filled with food particles.

Zooplankton

Kingdom Protista – Protozoans, Ciliates

Didinium sp.

• Didinium are unicellular and have an oval shape and two rows of cilia

• Front ends in a pointed snout (cytosome).

• Free-living carnivores

• Feed on other protists, dinoflagellates, and green algae

Zooplankton

Kingdom Protista – Protozoans, Ciliates

Stentor sp.

• Among the largest aquatic protozoans. Up to 2 mm long, they are larger than some of the smallest multicellular organisms

• Usually attach to substrates and form a trumpet shape.

• If they are free-swimming, they assume an oval or pear shape.

• A major characteristic of Stentor is the rapid contraction and extension of the cell body.

Zooplankton

Phylum Rotifera – Rotifers

Keratella sp.

• A footless rotifer which possesses a protective covering, or lorica, made up of hexagonal plates

• Has a crown of anterior spines

• May or may not have a posterior spine

Zooplankton

Phylum Arthropoda, Class Crustacea, Order Ostracoda – Seed Shrimp

Unidentified Ostracod

• Jointed appendages

• Body flattened from side to side and protected by a bivalve-like, chitinous or calcareous valve or "shell".

• They have a wide range of diets, and the group includes carnivores, herbivores, scavengers, and filter feeders.

Zooplankton

Phylum Arthropoda, Class Crustacea, Order Copepoda – Seed Shrimp

Cyclopoid Copepod (likely Cyclops sp.)

• Jointed body and appendages

• With a teardrop shaped body and large antennae.

• Have a compound, median single eye, usually bright red and in the centre of the transparent head

• Cyclopoid copepods have antennae shorter than length of body

Zooplankton

Phylum Arthropoda, Class Crustacea, Larval Stage

Unidentified Nauplius larva

• Jointed appendages

• Oval body with 3 pair of appendages

• Immature form of copepods, cladocerans, and ostracods