Tursiops truncatus [tur sE' ops
trun' kah tuhs]
The bottle-nosed dolphin is
10-14 feet long and weighs up to 1,100 pounds,
with males being slightly larger than females.
Its flippers taper to a point, and its dorsal fin
has a harply-pointed apex that is directed
backwards. The body is light gray to black in
color, with the belly always being lighter than
the rest of the body.
The most distinguishing feature
of the bottle-nosed dolphin is its short, thick
beak with 20-28 sharp conical teeth on each side
of the jaw. These teeth are what makes the
bottle-nosed dolphin's lower jaw seem to protrude
beyond the upper jaw, which in turn creates the
bottle-nosed dolphin's characteristic
Distribution and Habitat
Bottle-nosed dolphins live in temperate and
warm waters around the globe, including all
oceans except the Arctic and the Mediterranean
Sea. They do not migrate, but will sometimes
travel long distances in search of food.
Fish make up the majority of the bottle-nosed
dolphin's diet, but squid and shrimp are also
taken. Prey is tracked by echolocation. Although
the bottle-nosed dolphin will dive as deep as 70
feet or more to take prey underwater, it usually
prefers to strike prey with its flukes, knocking
it clear out of the water and then catching it in
its mouth. Groups of dolphins will also hunt in
packs, herding schools of small fish into an
increasingly smaller area and picking off
stragglers. Bottle-nosed dolphins are also known
to follow fishing boats and feast on leftover
bait and castoffs.
Breeding activity peaks in March and April,
during which period males compete viciously for
females. Once a male has spotted a potential mate
and fought off any competition he will posture
and gesture to the female until she either allows
him to mate with her or swims away.
One calf is born after a gestation period of
twelve months. The mother will help her newborn
calf to the surface so it can breathe, but it can
swim on its own soon after birth. The calf will
stay as close to its mother as possible for the
first couple of weeks, but will start taking off
on its own for short "hunting trips" as
it grows. It will be weaned at 18-20 months, but
will stay with its mother until 4-5 years of age.
The mother will not mate until her calf is
The age of sexual maturity varies greatly by
geographic population, ranging from 5 to 12 years
for females and 9 to 13 for males, and females as
old as 45 years have given birth to healthy
calves. Average life span in the wild is 40-50
Habits and Behaviors
Bottle-nosed dolphins live and travel in pods
containing about a dozen or so individuals of
both sexes and all ages. There are no leaders in
a pod, but there is a hierarchy based on size.
The process by which individual dolphins come
together into various pods is not known, nor is
it known whether individual dolphins stay with
one pod for life or move from one pod to another.
As social animals, bottle-nosed dolphins have
developed a very complex communications system of
squeaks and whistles, with each individual
dolphin having its own distinctive whistle.
While individual animals of many species are
known to show distress when another of their kind
is injured or sick, and there are many examples
of one animal putting itself at risk to protect
another, the bottle-nosed dolphin is one of the
few animals known to actually "come to the
rescue" of a sick or injured
"colleague." It is not at all uncommon
for one, two, or more individual dolphins to help
an injured "comrade" to the surface so
it can breathe, and for them to stay with him/her
until it can either stay at the surface on its
own or dies.
The swimming motion of the bottle-nosed
dolphin is an up-and-down movement of the fluke,
and it can swim at speeds of over 18 miles per
Although it can dive to depths of 70 feet or
more and stay submerged for up to 15 minutes, the
bottle-nosed dolphin typically surfaces to
breathe two or three times a minute. It is also
very fond of leaping clear out of the water and
can get as high as 16 feet above the surface
before landing with a splash on its back or side.
Because bottle-nosed dolphins are among the
most intelligent animals in the sea, and because
they are very active and playful, they are star
attractions at marine parks around the world.
A bottle-nosed dolphin was the star of
"Flipper," a television series that
aired from 1964 to 1967.
Although many people use the terms
"dolphin" and "porpoise"
interchangeably, dolphins are actually a subgroup
with porpoises, a group that also includes the
orca (killer whale) and beluga whale.
Bottle-nosed dolphins are threatened by
commercial fishing, especially tuna fishing, but
their population appears fairly consistent.
Although they are not listed as an endangered
species, they are protected by law in the U.S.
and other nations.
genus & species Tursiops truncatus
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