Water Fleas

Cladocera

Classification

Phylum: Arthropoda
Subphylum: Crustacea
Class: Branchiopoda
Order: Diplostraca
Suborder: Cladocera

Pronunciation

How to pronounce Cladocera: /kləˈdɒsərə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Sida crystallina 82345394 by Ivan Sinkov. Used under a CC BY 4.0 license.

Holopedium gibberum 209626837 by Stephanie Tran. Used under a CC BY 4.0 license.

Crustacea (Maididea, Pl. 89) (7929824180) by Dana, James Dwight. Used under a Public domain license.

Sida crystallina 53113460 by Dmitry Kulakov. Used under a CC BY 4.0 license.

Polyphemus pediculus 53113199 by Dmitry Kulakov. Used under a CC BY 4.0 license.

Penilia avirostris 146626828 by Lukas Schärer. Used under a CC BY 4.0 license.

Summary

Cladocera, or water fleas, are small freshwater crustaceans characterized by their unique morphology and reproductive strategies, notably cyclical parthenogenesis, allowing them to thrive in various aquatic environments.

Physical Characteristics

Body less than 5 mm long, covered by a thin carapace that does not enclose the head. Head down-turned with a single compound eye and two pairs of antennae. Body not obviously segmented, with lobed appendages on the thorax.

Identification Tips

Look for the distinctive setae pattern on the second antennae, and the presence of a cervical sinus may help in differentiating species.

Habitat

Aquatic habitats, commonly found in freshwater environments including vernal pools.

Distribution

Over 1,000 recognized species globally, many remain undescribed, with cosmopolitan distributions due to the ability to produce dormant eggs.

Diet

Feeds primarily on detritus, algae, and bacteria; some species are also predatory.

Life Cycle

Lifecycle dominated by cyclical parthenogenesis; females produce clones asexually under favorable conditions and transition to sexual reproduction that creates dormant eggs in harsher conditions.

Reproduction

Primarily asexual reproduction through parthenogenesis; sexual reproduction occurs later in the season to produce drought-resistant eggs.

Ecosystem Role

Serves as a key component in aquatic food webs, feeding on organic matter and serving as prey for larger aquatic organisms.

Collecting Methods

Net sampling in freshwater habitats
Sediment sampling from lakes and ponds

Preservation Methods

Fixation in ethanol or formaldehyde
Freeze-drying for long-term storage

Evolution

Originated significantly earlier than their first fossils found in the Jurassic; modern forms suggest a lineage that stretches back to the Paleozoic.

Similar Taxa

Misconceptions

Often misidentified due to their small size and resemblance to other small crustaceans.