Body smooth except for a spine between the insertions of gnathopod 2, cephalon flattened anteriorly. Length of largest male 22 mm, largest female 12 mm, smallest ovigerous female 6.4 mm.
Large males with articles 2-3 of the peduncle of antenna 1 slightly shorter than antenna 2, article 3 subequal in length to article 2, article 1 less than one-half the length of article 2, articles of peduncle expanded. In females and small males the peduncle of antenna 1 sometimes shorter than antenna 2.
Mouthparts typical of the genus, lacinia mobilis of right mandible 5-toothed.
Propodus of gnathopod 1 with 2 proximal grasping spines, grasping margin of dactylus and propodus serrate. Basis of gnathopod 2 short and stout, less than one-half of the length of pereionite 2, anterodistal margin produced into triangular projection; ischiurn and merus with posterodistal margin pointed in larger males; palm of propodus with numerous setae, single proximal grasping spine, distally with large rectangular tooth and slightly proximal tooth.
Gills ovate to elliptical, more ovate in larger males.
Propodus of pereiopods 5-7 robust with 2 proximal grasping spines, palm expanded slightly near grasping spines and with numerous setae.
Abdomen of male and female typical of genus.
C. equilibra has been collected from various habitats including sea grass, red and green algae, sponges, hydroids, alcyonarians, bryozoans and colonial ascidians. This species ranges in depth from the surface to 3000 m.
Sweden and Norway to the Mediterranean Sea including the British Islands; Black Sea; Azores; tropical West Africa; St. Helena Island, South Africa; Madagascar; Mid-North Atlantic and Sargasso Sea; Bermuda; east coast of United States; Texas; Venezuela; Brazil; Argentina; Chile; Taboga Island, Panama; between Panama and the Galapagos Islands; California; Hawaii; Japan; Philippine Islands; Cook Strait; Australia; New Zealand; Tasmania; Hong Kong; Malaysia.