• Postabdominal claw with one basal spine and a secondary tooth in the middle
• Postabdomen with minute marginal denticles (barely visible at 400x magnification), lateral denticles prominent
• Antennal setae formula 1-1-3 / 0-0-3
• Inferoposteal angle usually with teeth, variable in number
• Crest on head and valve, relative size of crest variable
• Valves obliquely striated
• Antennules with one terminal sensilla much long than the rest

• A common inhabitant of the littoral region in lakes and other small bodies of water. It is most frequently found in association with vegetation though occasionally will be found on bare rocky shores or sand (1).

• Acroperus harpae is an active species that can swim rapidly as well as crawl. Crawling is achieved through the use of the first trunk limbs with the dorsal crest on the headshield and carapace providing stability. When settled on its ventral margin the long antennae are extended posteriorly and act as props for balancing (1).

(1) FRYER, G. 1968. Evolution and adaptive radiation in the Chydoridae (Crustacea: Cladocera): a study in comparative functional morphology and ecology. Philos. Trans. R. Soc. Lond., B, Biol. Sci. 254: 221-382 + 384-385.