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Communication in bottlenose dolphins appears to be
extensive and complex. A dolphin maintains an intricate
social network that includes a few close associates (such
as mothers and calves or pair-bonded males), plus more
casual relationships with others who come and go within
a larger group. Dolphins hunt together to find food. Pods
of dolphins coordinate their movements to
herd prey, and then take turns swimming into the middle
of the assembled fish to eat. There is still much to
learn about how
dolphins communicate though a number of generalities
have emerged from research.
Sound travels 4.5 – 5
times faster through water than through the air. For
this reason dolphins rely on sound for communication
more than any other mode. Scientists believe that every
bottlenose dolphin develops a distinctive high-pitched
whistle, called a signature
whistle (Tyack, 2000). This whistle appears to serve
as a means of individual identification, much like a
name. It may let the rest of the pod know which pod members
are around, where they are, and, perhaps, something about
their mental state. Dolphins in distress sometimes emit
their signature whistles very loudly. Whistles may serve
to establish or maintain vocal or physical contact between
dolphins. Dolphins often respond to another dolphin’s
whistle by whistling themselves or moving toward the
whistler. If they become separated, a young calf and
its mother whistle frequently until reunited. Dolphins
also whistle when separated from other group members.
Dolphins do not always respond immediately to another
dolphin whistling. Sometimes, many dolphins in the group
whistle at once, repeating their signature whistles over
and over. In this case, the whistling may help the dolphins
keep track of each other.
Bottlenose dolphins also seem to whistle while foraging
on various prey items (Acevedo-Guiterrez 2004). Scientists
believe that as a group of dolphins finds a school of
potential prey they will vocalize more frequently. This
increase in vocalizations attracts more dolphins to the
area that can assist with rounding up the fish, allowing
all individuals to get a larger meal. An increase in
the number of dolphins nearby also provides safety for
all individuals, as sharks and other large predators
are likely to want to feed from the same food source
the dolphins have discovered.
Dolphins are capable of imitating certain sounds very
accurately and often learn other dolphins' whistles.
One reason for imitating another dolphin's whistle may
be to get its attention within a large group. Preliminary
research seems to support this idea although details
of the exact reason for imitation are still under investigation.
Dolphins may use other sounds besides whistles to communicate.
Courtship behavior can yield pulsed yelps. When under
duress, dolphins emit pulsed squeaks. Aggressive confrontation
can produce buzzing click-trains.
Dolphins do not generally
rely on visual communication, although they have excellent
eyesight both above and below the water’s surface.
There is often silt and other particles floating in
the water column that can make it difficult for dolphins
to communicate visually over long distances. However,
when close to each other, body language may play a
role in dolphin communication. Researchers are still
studying the behaviors and situations when dolphins
use body language and there are still many questions
regarding the meaning of any specific body movement.
Following is a list of dolphin behaviors observed here
at Dolphin Research Center. These behaviors are possibly
used as a means of visual communication.
Arch: Bend head and tail ventrally.
Eyewhite display:
Rolling eyes, showing the whites.
Flex: Bend head and tail dorsally.
Headwag: Rapid, side
to side shaking of the head.
Play dead: Roll
over submissively in the vicinity of another dolphin.
Snit: Sharp, sideways head jerk with
closed or open jaws; may be accompanied by sound.*
*May indicate agitation or aggressive behavior.
To some extent, dolphins may also communicate by touch.
Calves swim close to their mothers, brushing their bodies
with their flanks and pectoral fins. This may serve to
strengthen their bond and promote or strengthen social
ties. On the other hand, dolphins use touch in rough,
aggressive ways during courtship and when establishing
dominance. They use their teeth to make parallel scratches,
called rake marks, on each other's skin. Scientists continue
to study these behaviors and the situations in which
dolphins use them to learn exactly what they might mean.
Below is a list of behaviors that we have observed our
dolphins using here at Dolphin Research Center, possibly
to communicate by touch.
Bite : Close mouth around body part
of another animal.*
Butt : Hit with melon or snout.*
Hold hands: Swim
with pectoral fins overlapping.
Mouth: Touch another animal with open
mouth.
Nuzzle: Touch or rub another animal
with closed mouth.
Pectoral Pat: Tap
or stroke with pectoral fins.
Push: Forcefully press against another
animal with head or rostrum.*
Ram: Hit another animal full force,
head-on.*
Rub: Two animals touch body parts,
moving against each other with friction.
Stranding on chest:
One animal inverted, lifting another out of water, putting
recipient between the flippers (often between mother
and calf).
Stranding on rostrum:
One animal lifting another out of the water, carrying
recipient on the rostrum (often between mother and calf).
Tail kick: Strike
with tail.*
Tooth rake: Draw
teeth across the body of another animal.*
*May indicate agitation or aggressive behavior.
For many years, researchers have looked for evidence
of a dolphin language, a way to share complicated information
such as stories, family histories, and philosophy in
the way that humans do. Although a few dolphins have
learned to use a simple artificial language consisting
of hand gestures or computer-generated whistles, extensive
research to date has failed to demonstrate a natural
language in dolphins.
References
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Guttman, Norman and Harry Kalish. 1958. Experiments
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 Copyright © 2007 Dolphin Research Center
Information Can Be Used with Proper Citing
Dolphin Research Center, 58901 Overseas Highway, Grassy Key, FL 33050-6019
305-289-1121 www.dolphins.org
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