They have dark, long, and slender bills and dark greyish-black feet and legs. They have a wingspan of 64-71 cm. The adult winter plumage is mostly identical except for white on the cheeks and throat and a dark spur extending back from the eye. An alternate form, or the bridled morph, only occurs in a population in the North Atlantic. It has an eye ring with a line extending toward the back of its head in addition to the regular adult plumage.
Chicks are downy when first hatched.
They are blackish brown on top and white underneath. When they are first hatched they weigh 55-95 grams. Juveniles are similar to adults except for their smaller size and darker heads. The common murre is mainly piscivorous. They are surface divers that can remain submerged for up to one minute at a time.