KLOROS

The Kloros are a chlorine-breathing, colonial insectoid species which developed an expansionnist space faring civilisation. They resemble man-size insects with a number of small tentacles protruding from their chest, a long, slender neck and a diminutive head containing a somewhat triangular-shaped proboscis and a pair of huge bug eyes. Their central nervous system brain is located in the abdominal region, and their head acts mainly as a support for the sensory organs. Their blood is green. Oxygen is deadly for them.

Kloros  have a respectable sense of morale. They lack the concept of familial bond, but do have an analogous "group bond" to their colony and always travel with their groups.

Source: Isaac Asimov, C-Chute (first published in the pulp sci-fi magazine Galaxy in 1951 and  later published in the book Nightfall and Other Stories).