East Pacific Dolphin
| East Pacific Dolphin | ||||||||||||
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East Pacific Dolphin ( Stenella longirostris ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Stenella longirostris | ||||||||||||
| ( Gray , 1828) |
The East Pacific dolphin ( Stenella longirostris ) is a species of the spotted dolphin ( Stenella ). It is also known as the spinner dolphin (from English to spin ), because representatives of this species make jumps in which they rotate quickly around their own body axis like a drill .
features
The body length of the East Pacific Dolphin varies somewhat, but is mostly in the range of 1.20 to 2.30 meters with a weight between 20 and 80 kg. They all have a triangular, hardly sickle-shaped dorsal fin and a long, narrow snout. The East Pacific dolphin is dark gray on the top and creamy white on the underside. Dark spots may stand out on the base of the tail, back, and throat. The snout is noticeably long and has a dark tip. There are several subspecies that can differ from one another in terms of their color and shape.
In the Atlantic there is a risk of confusion with the Clymene dolphin , which also behaves similarly.
behavior
As social animals, East Pacific dolphins form groups of a few to several thousand animals. Very playful and acrobatic, they are known to “ride” the bow waves of boats. The reason for their characteristic rotations is so far unknown, although observed individual specimens have carried out up to 14 of these "spinnings" in a row.
distribution
East Pacific dolphins are most common in the East Pacific, for example off Hawaii and Mexico , but are common in tropical seas around the world. They prefer deep ocean areas of the high seas .
Taxonomy
The East Pacific dolphin was first described by John Edward Gray in 1828 and was given the name " longirostris " because of its long snout. Today four subspecies are distinguished from this species:
- S. l. orientalis as an eastern subspecies in the tropical east Pacific.
- S. l. centroamericana in the area of Central America and Costa Rica , as well as in the East Pacific.
- S. l. longirostris as nominate form also known as Gray's Spinner Dolphin in the central Pacific especially around Hawaii .
- S. l. roseiventris , the smallest form, was first discovered in the Gulf of Thailand .
In addition to these forms, there is great variability, with some color variants being typical for individual regions and populations .
threat
The East Pacific dolphin is currently not considered threatened. The populations living in the tropical east Pacific are often associated with schools of yellowfin tuna . A biological phenomenon that only occurs in this marine region. Because a school of dolphins can easily be observed from boats or helicopters, the dolphin school was circled with a purse seine net when fishing for tuna , which was then drawn in from below. In this way, more than 7 million dolphins were killed as bycatch between the late 1950s and the 1990s .
The populations in the tropical east Pacific have not recovered from this to this day; it is assumed that around half of the total population disappeared. The total population is about 900,000.
swell
- ↑ Earth Island Institute (English) ( Memento of the original from December 26, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ SAFE - International Control Program for Dolphin-Safe Tuna. Society for the rescue of the dolphins V., accessed on June 26, 2017 .
Web links
- Stenella longirostris in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Retrieved on 11 May, 2006.