ZOOPLANKTON

Diversity of the Heterotrophic Plankton Community

Major Groups of Zooplankton

• Ciliates• Rhizopods• Rotifers• Cladocerans• Copepods

Ciliate Zooplankton

• Animal-like unicellular heterotrophs.• All have two different types of nuclei.• They move and feed by cilia.

Some common ciliates in the microzooplankton community

• Stentor

• Halteria

• Tintinnida

Rhizopod Zooplankton

• These are amoeboid unicellular heterotrophs• Most common taxa observed in the

microzooplankton are thecate like Difflugia.

Actinopod Zooplankton

• These are free-floating cells with radiating axopods. e.g. Actinosphaerium.

Turbellarian Zooplankton

• These are free-living flatworms that live in stagnant pools and eutrophic lakes. e.g. Stenostomum

Rotiferan Zooplankton

• Animal heterotrophs that feed by ciliary pads surrounding the mouth.

• All have a specialized “jaws” called trophi in the gullet.

• Many are covered by a lorica.

Typical Life Cycle of a Rotifer

Some Rotifers in the Zooplankton

• Keratella

• Polyarthra

• Filinia

More Rotifers

• Brachionus

• Asplanchna

• Conochilus

Annelid Zooplankton

• Oligochaete segmented worm. e.g. Aeolosoma

Arthropod Zooplankters

Most freshwater taxa are Crustaceans (arthropods with cephalothorax and abdomen)– Order Anostraca– Order Ostracoda– Order Cladocera– Order Copepoda

• Suborder Calanoida• Suborder Cyclopoida• Suborder Harpacticoida

Anostracan Zooplankton

• Fairy Shrimp

• Clam Shrimp

• Tadpole Shrimp

Ostracod Zooplankters

• Sometimes called seed shrimp. Rarely in the euplankton.

Cladoceran Zooplankton

Cladoceran Life Cycle

Filter-Feeding Cladocerans

• Holopedium

• Diaphanosoma

• Chydorus

More Filter-Feeding Cladocerans

• Daphnia

• Bosmina

• Moina

Predaceous Cladocerans

• Leptodora

• Polyphemus

Copepod Diversity

• Suborder Cyclopoida

• Suborder Calanoida

• Suborder Harpacticoida

Copepod Life Cycle

Calanoid Copepods

• Diaptomus

• Epischura

• Limnocalanus

Cyclopoid Copepods

• Cyclops

• Macrocyclops

• Megacyclops

Harpacticoid Copepods