North and South Atlantic Oceans, including the Mediterranean
S. rayi was a species of this genus found in North Carolina, in the early Pliocene.[5]
The common name for species in this genus is the "spotted dolphins" or the "bridled dolphins".[2][3] They are found in temperate and tropical seas all around the world.[2][3] Individuals of several species begin their lives spotless and become steadily more covered in darker spots as they get older.[2][3]
The genus name comes from the Greekstenos meaning narrow.[2][3] It was coined by John Gray in 1866 when he intended it as a subgenus of Steno.[2] Modern taxonomists recognise two genera.[2][3]
The clymene dolphin (S. clymene) is the only confirmed case of hybrid speciation in marine mammals, descending from the spinner dolphin (S. longirostris) and the striped dolphin (S. coeruleoalba).[6]
Stenella dolphins tend to be more active during nighttime and spend their daytime resting. Although these dolphins are supposed to spend 60% of their daytime resting, they happen to be exposed to human activities for 80% of their day. These patterns of sleep deprivation can have negative impact on their resting habit and leads to decline in their population size.[7]
^Walker, Ernest Pillsbury; Ronald M. Nowak; John E. Heyning; Randall R. Reeves; Brent S. Stewart; John E. Heyning; Randall R. Reeves; Brent S. Stewart (2003). Walker's Marine Mammals of the World. JHU Press. p. 264. ISBN9780801873430.