Spinner Dolphin (Long-snouted) - Stenella longirostris

Spinner Dolphin (Long-snouted)
Eastern Pacific form
Stenella longirostris

Other Names: Longsnout, Spinner, Long-beaked Dolphin, Rollover

Habitat: Offshore and inshore

Status: Common

Population: Unknown

Threats: Entanglement in fishing nets, hunting/whaling

Group Size: 5-200, sometimes in larger, mixed schools

Fin Position: Center

Newborns: 28-34 in (70-85 cm), Unknown weight

Adults: 4 ¼-7 ft (1.3-2.1 m), 100-165 lb. (45-75 kg)

Diet: Squid or octopus, fish, and krill or other crustaceans

Teeth: 88-128 on top row, 84-124 on bottom row

Description

Dorsal fin:

- leans forward in large males
- dorsal fin shape highly variable between populations and becomes more erect with age
- triangular or slightly falcate fin (whitebelly form)
- slightly falcate fin (Hawaiian form)

Flukes:

- flukes have "swept-back" appearance
- slight notch in middle
- pointed tips
- flukes medium to dark gray on both sides

Flippers:

- long, pointed flippers

Other characteristics:

- long, thin beak
- crease where beak joins forehead
- distinct but gently sloping forehead
- predominately dark gray body
- prominent keels above and below tail stock on adult males only
- slender body
- creamy white patch on belly (variable)
- 3 distinct patches of color (whitebelly form)
- 3 distinct areas of coloration (Hawaiian form)
- slightly larger and dark than whitebelly form (Hawaiian form)
- dark gray stripe from eye to flipper
- black "lips"
- dark-tipped beak

Behavior

- when breaching, hurls itself up to 9 ¾ ft (3 m) into the air, then twists its body into sinuous curves or spins round on its longitudinal axis up to 7 times in a single leap
- may also be seen breaching in the normal way
- readily bow-rides in most areas (will come to bow of a boat from far away and may stay for half an hour or more) but much more nervous in eastern tropical Pacific and rarely approaches boats in Lesser Antilles, Caribbean
- large schools often churn water into a foam when swimming
- often associates with Pantropical Spotted Dolphins, Yellowfin Tuna, and seabirds in the eastern tropical Pacific; may be seen with other cetaceans throughout range

Distribution

- tropical and subtropical waters in the Atlantic, Indian, and Pacific Oceans
- sometimes occurs in warm temperate waters, but mainly tropical
- each variety has a more limited range than the species as a whole: for example, the Costa Rican form is found only in a narrow band of water less than 95 miles (150 km) wide off western Central America; and the eastern form is found from the tip of Baja California, Mexico, south to the equator and offshore to about 125º
- two or more varieties may occur in the same area
- distribution in the Atlantic poorly known
- most common far out to sea, especially in the eastern tropical Pacific, but also found close to shore, for example of southeastern USA and around some islands
- the Hawaiian form seems to rest inshore by day and moves to feed offshore at night

e-mail questions, comments, and/or suggestions to
wcrc@sci.tamucc.edu

Internet Coordinator: Candice Orca Mottet

e-mail questions, comments, and/or suggestions to wcrc@sci.tamucc.edu

e-mail questions, comments, and/or suggestions to
wcrc@sci.tamucc.edu