[1] Halocaridina rubra are small red shrimp, which can also appear yellow or orange, and are rarely longer than 1.5 cm (0.6 in).

Its habitat is unique and sparsely represented on five of the eight high Hawaiian Islands (Maui, Kahoʻolawe, Oʻahu, Molokaʻi and Hawaiʻi).

[1] ʻŌpaeʻula are herbivorous and detritivorous shrimp occupying both hypogeal (subterranean) and epigeal (surface) anchialine waters.

[4] Typical food of ʻōpaeʻula is algal and bacterial mats on the surface of rocks and other substrates in anchialine pools.

[5] ʻŌpaeʻula are social creatures and are rarely seen fighting, in fact when unstressed they often cluster together while eating or sunbathing.