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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 |
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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.
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