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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