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BOTTLENOSE DOLPHIN
Tursiops truncatus
(Montagu 1821)
DERIVATION: from the Latin tursio for an animal like the dolphin; from
the Greek ops for face; from the Latin truncare for cut off.
A question often asked is what is the difference between dolphins and
porpoises. A general rule to differentiate between them is the shape of
their beak or nose. Porpoises tend to have a blunter shaped face, lacking
the distinguished beak of dolphins. The dentition of the two also differs.
Porpoises have spade-shaped teeth while dolphins have conical-shaped teeth.
Bottlenose dolphins display perfect examples of these "dolphin-like
features."
In all areas where bottlenose dolphins have been studied in the wild,
there appears to be two populations: coastal and offshore. Differences
between them have been studied and continue to be explored, but presently
there exists no conclusive information distinguishing these two populations.
Bottlenose dolphins usually form groups of fewer than ten (coastal) or
25 (offshore) individuals, though groups of several hundred have been
reported from some offshore areas.
Males reach sexual maturity at 10 to 12 years; females at 5 to 12. Females
bear a single calf every second or third year with a gestation of about
12 months. Calves nurse for a year or more. They are closely tended by
adults during the first six months of their lives. "Babysitting"
has been observed, in which nearby adults remain with a calf as its mother
forages for food. As they age, young dolphins become more independent,
tasting scraps of food in the wake of feeding adults and gradually learn
to hunt on their own. Echolocation and other feeding-related behavior
is most likely learned during this period of weaning.
Coastal bottlenose dolphins feed on a variety of foods, eating a wide
variety of fish and invertebrates. They have adapted their feeding strategies
to take advantage of human activities, eating netted fish, trash fish
discarded by fishermen, and fish attracted to piers and idle boats.
Offshore bottlenose dolphins prefer a squid diet and often travel with
groups of squid-loving pilot whales. The color of bottlenose dolphins
is a subtle blend of brown to charcoal, with lighter sides and a light
belly. Variations of color include all black, albino, and cinnamon-colored
dolphins. Spots are present on some individuals.
Teeth number from 18 to 26 in each row. In older dolphins, teeth are often
worn down, particularly in coastal populations, probably reflecting differences
in diet and feeding habits between the two populations. Males are larger
than females. Length at maturity is 11-12 feet; females are slightly shorter.
They dorsal fin is moderately tall and falcate. Bottlenose dolphins are
mostly cosmopolitan and absent only in polar regions.
They are the most familiar marine mammal in the world as bottlenoses are
the most common captive species found in hotel tanks, amusements parks
and oceanariums throughout many countries. These are the dolphins that
often befriend humans in the wild, as their curiosity and coastal range
brings them into frequent human contact. In New Zealand, a bottlenose
would come into shallow water, play with children, and even let them ride
on its back. "Georgy Girl," a female bottlenose in Florida,
did this same behavior The T.V. star "Flipper" captured the
public love and admiration of dolphins, but unfortunately for them, this
has become a fatal attraction.
Captive dolphins are often cramped abused, isolated, exposed to human
disease, malnourished, and always have a shortened life. One of the "Flippers,"
Susie, was sold to a traveling show. She died from exposure while being
exhibited at a German shopping mall in the dead of winter.
By: Maris Sidenstecker