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The name:
This dolphin's name comes from its tendency to leap into the air and spin on its
long axis several times before falling back into the water. The word Stenella
from the Greek
word stenos for
"narrow" apparently refers to the long,
narrow rostrum. This
description is reconfirmed by the derivation of the word longirostris,
from the Latin words, longus for "long beak".
The look:
The spinner dolphin is quite slender with a long,
thin rostrum. Its dorsal fin varies greatly from falcate to triangular and even
canted forward in the Costa Rican population; moreso in the adult males. Three
discrete subspecies have been described with slight differences in appearance.
However, the generally have dark stripes running from the eyes to flippers.
Their lips and end of the beak are also darkly colored. The rest of their
markings and coloration range from dark gray to white on the belly. These
variations are due to the genetic separation of the stocks
The size:
Along with differences in markings, there are also some differences in the
overall build of the animal between the populations. Some are more slender or
stockier than others. Overall, spinner dolphins are about 2-2.5 m long at
adulthood with males being a bit larger than females. Their weight tends to be
at least 77 kg.
The location in
Africa: Spinner dolphins are found in an almost
all the world's oceans, but are restricted to tropical, subtropical, and warm
temperate waters. They are generally found in pelagic waters, and specimens have
been taken from Madagascar as well as from Eastern and Western Africa.
Interesting facts:
Besides their remarkable aerial acrobatics, spinners are also well-known for
their extreme gregarious nature as they often travel in groups of several
hundred to several thousand individuals. They are also sometimes associated with
pan -tropical spotted dolphins as well as common dolphins.
Human impacts:
Their strong herding instincts, as well as their
close association with yellow fin tuna, makes them quite vulnerable to
incidental capture in the tuna industry purse seine fisheries in the Eastern
Tropical Pacific Ocean. Because of this, their populations in this region of the
world have been greatly reduced in recent decades. There is also probably
fisheries interactions off West Africa.
Subspecies:
Possibly five or more, including a dwarf variety in Gulf of Thailand.
Life span:
Unknown.
Statistics:
Body length: 1.3-2.1m, Weight: 45-75kg.
Physical
Description: Spinner dolphins are slender-bodied with a dark grey back,
pearl sides and a white belly. The beak is long and slender, and they have a
tall erect dorsal fin.
Distribution:
They live in tropical and subtropical waters of the Atlantic, Pacific and Indian
Oceans, often near islands.
Diet: They
feed on fish, squid and shrimp.
Behavior: Spinner dolphins typically occur in schools of
5-200 individuals, although groupings of 1,000 individuals have been reported.
They are very sociable with their own species and other species, such as spotted
dolphins.
Notes:
Spinner dolphins spin on a longitudinal axis.
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