In
the ocean, the "school" (or, in the case of dolphins, the "pod") is the basic social unit. It provides for a cooperative,
social way of life and increases the chances for individual survival. The pod uses both acoustic and non-acoustic means
of communication. Cooperation and forming alliances are ways in which the more complex mammals attempt to manipulate
their social environment. Such alliances require sophisticated means of communication in order to manage relationships. Dolphins
do this by forming fluid, temporary groups called "pods", typically consisting of 2-15 animals. Dolphins
are very social creatures and appear to need each other while hunting, defending themselves and their pods, and (obviously)
mating. Animals in these pods join, split up and rejoin pods in different combinations. Pods may combine for several minutes
or hours to form larger social groups called "herds". Pod size appears to be related to the availability of food and the size
and openness and depth of their environment. In areas of high food availability, pods can temporarily join together to form
a "super pod", exceeding 1,000 dolphins. In deeper parts of the ocean there have been reports of super pods reaching over
a mile in length, requiring merchant ships to stop while these pods pass safely by. More shallow areas of the ocean support
pod sizes often less than 20 in number. The composition and population of these pods are constantly changing, some dolphins
moving into these pods for only minutes or hours before leaving. Pod composition is largely based on sex, age and reproductive
status.
Pods provide advantages
for the dolphin. Small foraging pods are an efficient means for feeding. Feeding in very large groups is not
efficient as it creates too much competition for the available food supply. Feeding alone is inefficient and dangerous. Protecting
the young is a strong motivation for cooperation between females within a pod.
Every dolphin develops a specific whistle pattern unique to that animal.
This is called a "signature whistle". Recent studies have shown that dolphins remember the signature whistles of "friends"
as well as "enemies" for up to 20 years. This so-called "social memory" is the longest recorded ever in the animal kingdom.
The ability to remember these whistles is an advantage to the dolphin who lives in a "fission-fusion" society where they continuously
join and leave different groups over a lifetime.
Most male mammals do not work cooperatively with each other in mating with females. Male dolphins,
on the other hand, find an advantage to working with their male pair-bond where mating is involved. They can work together
to "impress" females with their pair-bond behavior and can cooperatively "herd" one or more females into mating situations.
They must work cooperatively yet they remain in reproductive competition with each other.
Dominance within the pod is established by the dominant animal
demonstrating aggressive behavior toward the sub-dominant animals. It does this by tail-slapping, jaw-popping, chasing and
raking. Another form of aggression is the production of clouds of bubbles from the blowhole. Older dominant animals become
repositories of learned behavior and act as group leaders to pass on this information to the young.
One
type of pod is made up of mothers and their calves. These maternity pods are called “nurseries” and
may also include elderly dolphins being protected within these pods. Babysitting (called "allomothering") in nursery
pods may change over time, even involving female dolphins of a different species. Atlantic Bottlenose pods consisting only
of mother-calf pairs and mothers with their most recent offspring are often found. “Juvenile” pods will include
males and females who have left the nurseries and are not yet sexually mature. These pods provide the environment in which
socially acceptable behaviors are learned. Once sexually mature, the females often return to their mothers' pods to raise
their own young. Adult males, on the other hand, remain in these juvenile pods longer, as they take longer to mature. Once
mature, they “pair-bond” with another male and come and go to mate with the females. These pair-bonds are intended
to be lifelong associations. Should a male lose his pair-bond, he often tries to pair up with another male. Adult males
rarely associate with juvenile males.
Factors affecting the cohesion of the pod are fright,
protection and family association. Factors which cause pods to disperse include aggression and the need to find food.
Stories of dolphins saving
humans and aggressively attacking sharks are often embellished. The Bottlenose will respond to a shark in one
of three ways: tolerating it, avoiding it or aggressively trying to drive it away. The dolphin's response to a particular
shark appears to be species-related, with the strongest reaction elicited to their known predators, tiger and bull sharks.
Dolphins have been observed attacking and killing sharks. Other observers have recorded a “scouting behavior”
in dolphins, where they appear to go out and scout out unfamiliar territory or objects and report back to their social groups.
Bottlenose dolphins may come to the aid of injured dolphins, vocalizing nearby,
or they may provide physical support for the weakened animal by bringing it to the surface to breathe. Altruistic acts between
dolphins are most likely reciprocal, acting as a form of social behavior. ("I'll help you, if you'll help me.")
Site Content
Understanddolphins.com contains information condensed from a number of reputable technical sources,
peer reviewed journal articles, and respected dolphin research facilities, as well as from my personal experiences and
observations as a dolphin VIP Tour Guide and Educator.
I have made every attempt to support the information presented in this site with video and still
photographic images. On a regular basis I plan to produce more of these images and will continue to update the site with these
as well as with any new and scientifically verified information which becomes available.
