Home | Is it a mite? Home | Glossary
Common names: water fleas, daphnia
Probability of encounter: high if intercept has standing water and from some soils if appropriate extraction techniques used (i.e. wet funnel, flotation).
Quarantine importance: unknown. Most species are suspension feeders on detritus and microbes.
Similarity to mites: small size, lack of clear segmentation
Normal adult length:
mostly 0.25 - 2 mm
Body tagmata: head (1 pair of antennae), trunk, postabdomen
Eyes: median fused compound eye, naupliar eye
Antennae: biramous, swimming
Mouthparts: mandibles without palps; one pair of maxillae
Legs: 5-6 pairs of swimming/ grasping/ filtering legs
Respiration: cutaneous and coxal epipodites of trunk limbs
Gonopore: various on trunk
Distinguishing features: Minute swimming crustaceans with head shield
and shell-like carapace, swimming 2nd antennae, dorsal brood chamber
Comments: Water fleas are normally considered aquatic organisms and would be expected primarily in moist intercepts (e.g. bromeliads); however, they also can be extracted with wet funnels from some soils. Eggs are brooded under the carapace which sometimes forms a protective capsule (ephippium) that allows aerial dispersal by wind.
Diversity: 4 suborders, 11 families, 80+ genera, >400 species.
References
The Cladoceran Website - http://www.cladocera.uoguelph.ca/