Leptodora kindtii

(Focke, 1844)

Glass Waterflea, Invisible Water Flea

Leptodora kindtii is a large, nearly transparent predatory cladoceran found in temperate lakes across the Northern Hemisphere. It is one of the largest water fleas, reaching up to 21 mm in length, and occupies the pelagic zone of freshwater systems where it functions as a significant . The exhibits pronounced seasonal , typically peaking in summer months with abundances exceeding 18,000 individuals per m² in some systems. Its have been impacted by competition and from cladocerans, particularly Bythotrephes longimanus, which has contributed to documented declines in abundance and body size in invaded lakes.

Pronunciation

How to pronounce Leptodora kindtii: /ˈlɛptəˌdɔːrə ˈkɪndiːaɪ/

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Identification

Distinguished from other cladocerans by its large size (up to 21 mm), nearly transparent body, and two prominent used for swimming. Possesses a single . The Leptodora contains only two ; L. kindtii is distinguished from L. richardi by geographic distribution, with L. kindtii being the widespread Northern Hemisphere species. In lakes where it coexists with Bythotrephes longimanus, L. kindtii can be differentiated by its generally smaller body size in contemporary and its tendency to occupy shallower depths during summer months.

Habitat

Pelagic zone of temperate lakes and ; occurs at both deep (>200 m) and shallow (<60 m) stations. Tolerates freshwater to oligohaline conditions, never occurring at salinities greater than 4 psu. Found in hydrodynamically variable environments including stagnant and actively flowing areas.

Distribution

Northern Hemisphere temperate lakes. Documented from Lake Michigan, Lake Constance, Lake Erie, Curonian Lagoon (SE Baltic Sea), and mainstem Missouri River in Montana, USA.

Seasonality

Present in pelagic zone from mid-May to November. peaks in summer, with timing varying by site; at stagnant freshwater sites, populations may peak approximately two weeks earlier than at hydrodynamically active sites, likely due to warmer early-season temperatures.

Diet

Juveniles consume smaller prey including Bosmina and the rotifer Conochilus. consume a broader size range including Bosmina, Daphnia, and copepods. Prey capture occurs by chance contact using legs.

Behavior

Performs diel vertical . Occupies shallower depths than coexisting Bythotrephes longimanus during summer months, particularly at deep stations; this differential vertical distribution may represent a spatial from . Exhibits declines and reduced body size in response to Bythotrephes longimanus, attributed to competition for food and direct predation.

Ecological Role

Top-down regulating grazing zooplankton . Daily consumption during peaks can equal 100% of daily zooplankton production in some systems. Serves as prey for planktivorous fish. Coexists with similar predators through temporal and spatial differentiation.

Similar Taxa

Bythotrephes longimanusCoexisting predatory cladoceran with which it shares similar ; distinguished by temporal appearance (B. longimanus appears slightly earlier), deeper summer distribution at deep stations, and larger body size in contemporary where they co-occur.
Leptodora richardiCongeneric distinguished by restricted distribution; L. richardi has limited range while L. kindtii is widespread across Northern Hemisphere.