Leachia are characterised by the presence of two parallel ridges bearing raised cartilage spikes, which run along the underside of the body near the head.

Like most glass squids, members of this genus possess a ring of light organs around their eyes.

Bioluminescent cells produce light that cancels the shadow cast by their large eyes.

Typical of cranchiid squids, juvenile Leachia species have stalked eyes.

Six species are considered valid by Voss, et al. (1992), who suggests there are 5 more that remain undescribed: