Adult males are 1,8-2,6 m long and weigh 80-140 kg.  Females are 1,7-2,3 m long and weigh 70-90 kg.  This is the smallest of the dolphin species in Icelandic waters.  Its snout is long and narrow, the dorsal fin back swept, long and pointed, and the fluke and flippers are rather small.  Each jaw contains 80-110 teeth.  The back is black, the front sides yellowish and pale green and light grey further back and the belly is white.  There are many colour variations between the many and different stocks of the world oceans.  The life expectancy of this species is unknown.  The common dolphin sustains itself on a great variety of fishes, sardines, anchovies, herring etc. and squid.

Research in the Pacific Ocean may suggest a population of about 1 million animals there and thus several millions world wide, but actually nothing is known about it yet, not even the number of animals in Icelandic waters.  Very little or nothing is known about the migration habits.  Sometimes shoals of thousands of animals are spotted.  They are playful and curious and follow vessels and larger whales, humpbacks, blue whales, sei whales etc.  The average diving depth seems to be about 40 m, but once a depth of 280 m was measured and a diving time of 8 minutes.

Many scientists do not agree on the classification of the different colour varieties of this species and little is known about the mating habits and the birth.  It seems that the cows reach puberty at 6-7 and the males at 5-12 years of age.  The calf is born in spring, summer, or autumn after a 10-11 months gestation period and is suckled for 14-19 months.  This species is not popular among the aquariums of the world because of its shyness in captivity.  The Russians, Turks, and Bulgarians almost hunted the common dolphin to extinction in the Black Sea during the early part of the 20th century.