Abstract
The amphipod, Hyalella azteca, was described by Saussure in 1856. Weckel (1907) discussed the synonomy of the species and credited its discovery to Bate (1862), who classified this species as Hyalella knickerbockeri. | Depending upon age and sex, this small crustacean ranges from 2 to 7 mm in length. Males are slightly larger than females of the same age. Sexual reproduction is obligatory and occurs throughout the year in the laboratory at 21C. Young are brooded in the marsupium of the female and released before her molt. This animal is of ecological interest since it is common and abundant in a good part of North and South America (Pennak, 1953) , and is therefore readily available for study. Hyalella feeds upon epiphytic growths on rooted aquatic plants, on dead organic material in the substrate, and on living plants, particularly filamentous green algae (Cooper, 1965). Laboratory investigations indicate that several aquatic invertebrates, especially several members of the order Odonata, feed upon Hyalella. Strong (1972) reported that Hyalella is a natural food source for at least six species of fish. Thus, late in the aquatic food chain.