Stenella Dolphins
 

Common Name: Spotted, Spinner or Striped Dolphins
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Stenella
Species: Five species:
Pantropical spotted dolphin Stenella attenuata
Atlantic spinner dolphin Stenella clymene
Striped dolphin Stenella coeruleoalba
Atlantic spotted dolphin Stenella frontalis
Pantropical spinner dolphin Stenella longirostris
Atlantic spotted dolphin Stenella frontalis



Genus: Stenella

The dolphins of the genus Stenella belong to the Mammalian Order Cetacea, in the suborder Odontoceti. All toothed whales belong to the suborder Odontoceti, which is Latin for "toothed whales". These dolphins belong to the oceanic dolphin family, Delphinidae. Other members of this family include the killer whale, long-beaked common dolphin, and pilot whale. The generic name, Stenella, is the Latin diminutive form of the Greek steno, which means "narrow". This refers to the longer rostrums of the species in this genus.
 


Atlantic spotted dolphin Stenella frontalis
 


Striped dolphins are light gray dorsally with a dark lateral stripe on each side, bordered by a white underside. Spinner dolphins are dark gray dorsally, tan or gray laterally and pale white or gray ventrally. Spotted dolphins have dark spots against a light background ventrally and light spots on a dark background dorsally and laterally. Spotted dolphins gain spots as they age. Adult striped, spotted and spinner dolphins are range from 4-7 feet in length. These dolphins weigh between 150-350lbs. Males are generally larger than females.
 


Pantropical spotted dolphin Stenella attenuata



These species prefer deep, clear offshore waters of the tropical and subtropical oceans. They feed on a variety of small ocean fish and squid. Groups of 20 or less are common in coastal waters, while larger groups of 50-100 are commonly observed on the open ocean. Juvenile males form smaller groups, while females with calves may join other females, forming larger groups. Groups are fluid, and individuals move freely among a variety of group sizes and compositions. Gestation lasts 10-12 months for most species. Calves of all specieas are 2-3ft in length at birth, reaching sexual maturity at 10-15 years for males, and 7-10 years for females.
 


Pantropical spotted dolphin Stenella attenuata



The specific name, attenuata, is Latin for “tapered”. However, the scientist responsible for naming this species, John E. Gray (1800-1875), may have understood attenuata to mean “sharp” because he referred to this species as the sharp-beaked dolphin. The pantropical spotted dolphin inhabits the temperate and tropical waters of all oceans.
 


Pantropical spotted dolphin Stenella attenuata
 


Atlantic spinner dolphin Stenella clymene

The specific name, clymene, is the probably named for the Greek nymph Clymene, a daughter of Oceanus, a mythical personification of the Atlantic Ocean. These animals were first named spinner dolphins by 18th century sailors because they regularly leap out from the water, rotating multiple times while in the air. Atlantic spinner dolphins inhabits the tropical waters of the Atlantic Ocean.

Atlantic spotted dolphin Stenella frontalis

The specific name, frontalis, is Latin for “forehead”, probably referring to the species' well-defined melon. The Atlantic spotted dolphin lives throughout the tropical waters of the Atlantic Ocean.
 


Atlantic spotted dolphin Stenella frontalis



Striped dolphin Stenella coeruleoalba

The specific name, coeruleoalba, is derived from the Latin coeruleus, meaning "blue", and albus, meaning "white”. This refers species’ dorsal coloration of light gray and ventral coloration of white. The striped dolphin inhabits tropical and temperate waters of all oceans.

Pantropical spinner dolphin Stenella longirostris

The specific name, longirostris, derived from the Latin longus, which means "long", and rostrum which means “snout”. This refers to the dolphin’s prominent beak. These animals were first named spinner dolphins by 18th century sailors because they regularly leap out from the water, rotating multiple times while in the air. The pantropical spinner dolphin lives throughout tropical and temperate waters of all oceans.
 


Pantropical spinner dolphin Stenella longirostris



Conservation

Dolphins of this genus have been heavily affected by the tuna fishing industry. The American tuna industry place restrictions and developed methods to protect dolphins from tuna nets with the advent of the Marine Mammal Protection Act of 1972. This decreased the number of dolphins killed by fishing nets each year. Foreign fishing industries were obligated to abide by similar U.S. standards via trade agreements. The current population estimates of the eastern tropical Pacific Ocean exceed one million. The pantropical spinner dolphin is estimated at 1.7 million, the pantropical spotted dolphin is estimated at 2.1 million, and the striped dolphin is estimated 1.9 million. Although these numbers seem large, they are significantly less than estimates taken during the 1960's.


 

CAC is a program of the Institute for the Study of Human-Animal Relations at Canisius College in Buffalo, NY.