Cyclopoida

Cyclopoid Copepods

Family Guides

Cyclopidae
Lernaeidae(anchorworms)

Cyclopoida is an order of small crustaceans within the class Copepoda, comprising approximately 30 . Members are primarily planktonic, inhabiting both marine and freshwater environments, and are distinguished by morphological features including shorter than the and combined. The order exhibits metamorphic larval development with embryos carried in paired or single sacs attached to the first abdominal somite. Molecular phylogenetic studies have reclassified the former order Poecilostomatoida as a lineage nested within Cyclopoida.

Lernaea by (c) Alan Couch, some rights reserved (CC BY). Used under a CC-BY license.

Diacyclops by (c) Kseniya Atuchina, some rights reserved (CC BY), uploaded by Kseniya Atuchina. Used under a CC-BY license.

Lernaeidae by no rights reserved, uploaded by Andrew Deacon. Used under a CC0 license.

Pronunciation

How to pronounce Cyclopoida: /sɪˈkloʊpoɪdə/

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Identification

Distinguished from other copepod orders by: (1) first shorter than plus length (vs. longer in Calanoida), and (2) uniramous second antennae. The main body occurs between segments 4 and 5. These features separate Cyclopoida from Calanoida and Harpacticoida.

Images

Habitat

Marine and freshwater planktonic environments. Documented from epipelagic ocean zones, glacial lakes, meadow puddles, and various lentic water bodies. Some occur in mountain and transitional zones between Nearctic and Neotropical regions.

Distribution

distribution spanning marine and freshwater systems globally. Documented occurrences include: Mediterranean Sea, North Atlantic (Norway, Sweden, Denmark), North America (Vermont, USA; Mexican fauna in Nearctic-Neotropical transition), Ukrainian Carpathians (Runa, Borzhava, Vododilnyi massifs), and South America (Colombia: Departamento del Tolima).

Life Cycle

Metamorphic larval development with distinct naupliar and copepodid stages. Embryos carried in paired or single sacs attached to first abdominal somite. Development includes stages from nauplii (I-III) through metanauplii (IV-VI) to .

Behavior

Capable of rapid movement. Some exhibit active ambush strategy rather than passive foraging. Males of at least some species (e.g., Oithona nana) alternate between immobile feeding phases and mobile mate-searching phases, with documented sacrificial involving autolysis to fuel prolonged partner search.

Ecological Role

Major components of plankton in marine and freshwater . High abundance documented in some (up to 253.5 thousand individuals/m³ in mountain meadow puddles). Contribute to trophic networks as both consumers and prey, though specific quantitative roles not detailed in sources.

Human Relevance

Subject of studies for biodiversity assessment and taxonomic identification. Some containing cyclopoids are considered conservation priorities due to concentration of aquatic diversity in mountain regions.

Similar Taxa

CalanoidaCalanoida have first longer than plus , and biramous second antennae, versus Cyclopoida's short first antennae and uniramous second antennae.
HarpacticoidaHarpacticoida typically have different body proportions and joint placement; Cyclopoida are distinguished by the specific combination of short first , uniramous second antennae, and joint between segments 4-5.

More Details

Taxonomic Revision

The suborder Poecilostomatoida, previously treated as a separate order, is now recognized as a lineage nested within Cyclopoida based on molecular phylogenetic evidence. This group is temporarily referred to as the 'poecilostome lineage' pending formal taxonomic revision.

Sex Determination

A ZW sex determination system has been predicted in at least one (Oithona nana), with highly female-biased sex ratios observed (male/female ratio <0.15) due to elevated male mortality.