Post by OldGreenVulture on Dec 3, 2019 12:37:02 GMT
Spinner Dolphin - Stenella longirostris.
Classification
CLASS: Mammalia
ORDER: Cetacea
SUBORDER: Odontoceti
FAMILY: Delphinidae
GENUS: Stenella
SPECIES: longirostris
Subspecies
There are four named subspecies:
1. Eastern Spinner Dolphin (Stenella longirostris orientalis), found in the tropical eastern Pacific.
2. Central American or Costa Rican Spinner Dolphin (Stenella longirostris centroamericana), also found in the tropical eastern Pacific.
3. Gray's or Hawaiian Spinner Dolphin (Stenella longirostris longirostris), found in the central Pacific around Hawaii but represents a mixed bag of broadly similar subtypes found throughout the world.
4. Dwarf Spinner Dolphin (Stenella longirostris roseiventris), first found in the Gulf of Thailand.
The first published reference to the spinner dolphin appeared in 1769. The Benedictine monk Dom Antoine-Joseph Pernety sighted a school of several hundred unusual dolphins off West Africa while on a voyage to the Falkland Islands in the South Atlantic. The dolphins "sprang out of the water in an extraordinary manner." They "leaped at least three or four feet high and turned round not less than three times in the air, as if they had been on a spit." Only the spinner dolphin has been seen to spin several times in the air like this in the wild (W. F. Perrin and James Gilpatrick, Jr.).
Physical Description
The body size, shape, and color patterns of the various forms differ according to geographical location. Spinners in general all share common characteristics: their bodies are slender, their beaks are long and thin (except for the Atlantic short-snouted spinner) and their flippers are small and pointed at the tips. Their coloring is in shades of dark gray, light gray, and white; most forms have white bellies.
Feeding
The spinner dolphin's diet consists of small fish and squid. Spinners have more teeth than other species of dolphins, with between 45 to 65 sharp, pointed teeth in each side of both the upper and lower jaws. They feed at night.
Reproduction
Females reach sexual maturity at about 4 to 7 years, males at about 7 to 10 years. A newborn calf averages 32 inches (80 cm) in length. The gestation period is 10 1/2 months, and the calving interval is between 2 to 3 years. Calves nurse for from 1 to 2 years.
Distribution
The Costa Rican spinner is found in large, close-knit groups of 1,000 or more animals in coastal waters less than 90 miles (150 km) off the western coast of Central America; the eastern spinner is a more oceanic species found in deep water off the coast of Mexico and the west coast of Central America, often travelling in large herds of thousands or more, sometimes in the company of spotted dolphins; the whitebelly spinner is distributed even further offshore from Mexico, Central America, and the Pacific region of northern South America, travelling in herds of 1,000 or more; the Hawai'ian spinner is common throughout the Hawai'ian Islands and congregates in herds of 200 or more.
Natural History
Spinner dolphins frequently travel in the company of other species, such as the spotted dolphin and, in Hawai'i, humpback whales. In the eastern tropical Pacific, spinner dolphins swim with yellowfin tuna, an association that has led to the slaughter of hundreds of thousands of spinners in the purse-seine tuna fishery. Known predators are sharks, killer whales, and possibly false killer whales, pygmy killer whales, and pilot whales.
Behavior
The unusual spinning behavior common to all spinner dolphins is most probably a function of communication. It correlates with the general alertness of a school, and occurs most frequently when the school is dispersed. It may also serve to dislodge parasites or remoras (a type of fish that attaches itself to other large fish, cetaceans, or ships).
Conservation Status
Whitebelly and eastern spinner dolphins in the eastern tropical Pacific have suffered enormous population losses as a result of entanglement in the nets of tuna fishermen. For a reason not yet known, they swim in herds above schools of yellowfin tuna. Instead of looking for tuna, the fishermen look for dolphins; when they find them, they encircle the herd with large nets called "purse seine" nets, capturing the dolphins along with the tuna. It is believed that the stock has declined by as much as 80% since the 1960s, when purse seining operations began. Spinner dolphins do well in captivity, and have been displayed in Hawai'i and elsewhere in the U.S., Indonesia, the Philippines, and Hong Kong.
From Carnivora.
carnivora.net/spinner-dolphin-stenella-longirostris-t2822.html
Classification
CLASS: Mammalia
ORDER: Cetacea
SUBORDER: Odontoceti
FAMILY: Delphinidae
GENUS: Stenella
SPECIES: longirostris
Subspecies
There are four named subspecies:
1. Eastern Spinner Dolphin (Stenella longirostris orientalis), found in the tropical eastern Pacific.
2. Central American or Costa Rican Spinner Dolphin (Stenella longirostris centroamericana), also found in the tropical eastern Pacific.
3. Gray's or Hawaiian Spinner Dolphin (Stenella longirostris longirostris), found in the central Pacific around Hawaii but represents a mixed bag of broadly similar subtypes found throughout the world.
4. Dwarf Spinner Dolphin (Stenella longirostris roseiventris), first found in the Gulf of Thailand.
The first published reference to the spinner dolphin appeared in 1769. The Benedictine monk Dom Antoine-Joseph Pernety sighted a school of several hundred unusual dolphins off West Africa while on a voyage to the Falkland Islands in the South Atlantic. The dolphins "sprang out of the water in an extraordinary manner." They "leaped at least three or four feet high and turned round not less than three times in the air, as if they had been on a spit." Only the spinner dolphin has been seen to spin several times in the air like this in the wild (W. F. Perrin and James Gilpatrick, Jr.).
Physical Description
The body size, shape, and color patterns of the various forms differ according to geographical location. Spinners in general all share common characteristics: their bodies are slender, their beaks are long and thin (except for the Atlantic short-snouted spinner) and their flippers are small and pointed at the tips. Their coloring is in shades of dark gray, light gray, and white; most forms have white bellies.
Feeding
The spinner dolphin's diet consists of small fish and squid. Spinners have more teeth than other species of dolphins, with between 45 to 65 sharp, pointed teeth in each side of both the upper and lower jaws. They feed at night.
Reproduction
Females reach sexual maturity at about 4 to 7 years, males at about 7 to 10 years. A newborn calf averages 32 inches (80 cm) in length. The gestation period is 10 1/2 months, and the calving interval is between 2 to 3 years. Calves nurse for from 1 to 2 years.
Distribution
The Costa Rican spinner is found in large, close-knit groups of 1,000 or more animals in coastal waters less than 90 miles (150 km) off the western coast of Central America; the eastern spinner is a more oceanic species found in deep water off the coast of Mexico and the west coast of Central America, often travelling in large herds of thousands or more, sometimes in the company of spotted dolphins; the whitebelly spinner is distributed even further offshore from Mexico, Central America, and the Pacific region of northern South America, travelling in herds of 1,000 or more; the Hawai'ian spinner is common throughout the Hawai'ian Islands and congregates in herds of 200 or more.
Natural History
Spinner dolphins frequently travel in the company of other species, such as the spotted dolphin and, in Hawai'i, humpback whales. In the eastern tropical Pacific, spinner dolphins swim with yellowfin tuna, an association that has led to the slaughter of hundreds of thousands of spinners in the purse-seine tuna fishery. Known predators are sharks, killer whales, and possibly false killer whales, pygmy killer whales, and pilot whales.
Behavior
The unusual spinning behavior common to all spinner dolphins is most probably a function of communication. It correlates with the general alertness of a school, and occurs most frequently when the school is dispersed. It may also serve to dislodge parasites or remoras (a type of fish that attaches itself to other large fish, cetaceans, or ships).
Conservation Status
Whitebelly and eastern spinner dolphins in the eastern tropical Pacific have suffered enormous population losses as a result of entanglement in the nets of tuna fishermen. For a reason not yet known, they swim in herds above schools of yellowfin tuna. Instead of looking for tuna, the fishermen look for dolphins; when they find them, they encircle the herd with large nets called "purse seine" nets, capturing the dolphins along with the tuna. It is believed that the stock has declined by as much as 80% since the 1960s, when purse seining operations began. Spinner dolphins do well in captivity, and have been displayed in Hawai'i and elsewhere in the U.S., Indonesia, the Philippines, and Hong Kong.
From Carnivora.
carnivora.net/spinner-dolphin-stenella-longirostris-t2822.html