2. INTRODUCTION
Dolphins are highly intelligent marine mammals and are part of the family of
toothed whales that includes orcas and pilot whales
There are 40 extant species named as dolphins.
Name derived from Greek word delphis, meaning womb.
3. Common bottlenose dolphin
KINGDOM : Animalia
PHYLUM : Chordata
CLASS : Mammalia
ORDER : Cetacea
FAMILY : Delphinidae
GENUS : Tursiops
SPECIES : T. truncatus
4. BOTTLENOSE DOLPHINS
Most common species
Familiar due to exposure they receive in captivity,
movies and programmes
Largest species of beaked dolphins
Inhabit temperate and tropical oceans and absent
from polar waters
Distribution is generally limited to surface water
temperatures of 10° to 32°C (50° to 90° F).
5. Habitat is usually warm temperate waters and they are greatly
adapted to survive in marine, estuarine as well as river waters.
They are not endangered or threatened
Worldwide population is about 6,00,000.
Median life spans between 8.3 and 17.4 years in wild and about 22.8
years in captivity.
As a dolphin ages, it periodically produces growth layer groups
(GLGs) of dental material. Age can be estimated by examining a sliced
section of a tooth and counting these layers.
Dolphins spent about 33% of each day sleeping
6. PHYSICAL CHARACTERISTICS
In general, 2 to 3.9 m (6.6 to 12.8 ft.) long
Males and females almost similar in appearance but males weigh twice as much as
females
Avg. weight is 150-200kg for a female while about 400kg for male
Body is streamlined, sleek and fusiform
Skin is smooth and rubbery without hairs and sweat glands
Skin colour- grey to dark grey on back; white on lower jaw and belly
Blubber present below the dermis
The rounded region of a dolphin's forehead is called the melon.
7. Well-defined rostrum (snout-like projection) in front of the melon.
Teeth are conical and interlocking.
Teeth are designed for grasping (not chewing) food.
Bottlenose dolphins have 18 to 26 teeth on each side of the upper and lower jaws, a total of
72 to 104 teeth.
Eyes are on the sides of the head, near the corners of the mouth.
A bottlenose dolphin breathes through its blowhole. It is usually covered with muscular
flap
8. SENSES
They have a larger brain size than same sized mammals
This may be due to an increased size of the auditory region to facilitate sound processing.
Thus, dolphins have a well-developed, acute sense of hearing.
They can hear tones with a frequency up to 160 kHz with the greatest sensitivity ranging
from 40 to 100 kHz (humans only up to 20kHz)
Acute vision- adapted for underwater vision mainly.
Primarily monocular
Skin sensitive to vibrations
Taste buds at base of tongue- can detect 3 or 4 primary tastes (sweet, bitter, sour, salty)
May not have sense of smell
9. COMMUNICATION
Sound production to navigate, communicate, hunt, and
avoid predators in dark or limited vision waters.
Produced by air movements in the nasal passage.
Tissue complex called dorsal bursa- phonic lips- tissue
vibrations produce sound
Can be clicks, squeaks, whistles etc
identifies itself with a signature whistle
A mother dolphin may whistle to her calf almost
continuously for several days after giving birth.
10. ECHOLOCATION
By producing clicking sounds and then receiving and interpreting the resulting
echo.
By this, dolphins can determine size, shape, speed, distance, direction, and even
some of the internal structure of objects in the water.
11. FOOD
During early morning and late afternoon
Predators- eat wide variety of fishes, squids, and crustaceans such as shrimps
Adult bottlenose dolphins eat approximately 4% to 6% of their body weight in food
per day.
A nursing mother's daily intake is considerably higher — about 8%.
A dolphin's stomach is compartmentalized for rapid digestion.
Hunting techniques include pinwheeling, drivers and blockers, strand feeding etc
Dolphins do not chew their food
Before eating large fishes, bottlenose dolphins shake them or rub them on the
ocean floor until suitable-size pieces break off.
13. REPRODUCTION
Females reach sexual maturity at 7 to 10 years and
males at 7-12 years
Breed throughout the year
Females ovulate 2-7 times and both sexes have multiple
mates
Births may occur in all seasons, but typically peaks
occur during spring, early summer and fall.
During courtship, dolphins engage in head-butting and
tooth-scratching.
Gestation period is about 12 months
14. A female dolphin can potentially bear a calf every two
years
Calves are born in the water
Assisting dolphin seen near mother and calf- auntie
dolphin- can be male as well
Calf is about 10-20kg at birth
A calf may nurse for up to 18 to 24 months
The calf suckles from nipples concealed in abdominal
mammary slits.
Calves begin to take a few fish at about 3 to 4 months
Mother-calf bonds are long-lasting; a calf typically stays
with its mother 3 to 6 years.
15. BEHAVIOUR
Bottlenose dolphins live in fluid social groups.
Primarily found in 2-15 individuals per group
These communities around the world are described as “fission-fusion” societies.
Bottlenose dolphin females form alliances primarily to obtain food resources and for
reproduction
Establish and maintain dominance through posturing, biting, chasing, jaw clapping,
smacking their tails on the water, emitting bubble clouds from their blowholes
Large adult male- protection, scouting
Aid injured dolphins and often seen with other toothed whales
16. THREATS
Variety of diseases and parasites can be responsible for dolphin deaths.
Natural predators include certain large shark species such as tiger sharks
(Galeocerdo cuvier), dusky sharks (Carcharhinus obscurus), bull sharks
(Carcharhinus leucas), and great white sharks (Carcharhinus carcharias).
They are affected by heavy boat traffic, habitat loss and pollution.
Bottlenose dolphins have been taken directly for meat, leather, oil, and meal (for
fertilizer and animal feed) in Peru, Japan etc.
In the course of fishing operations, gear and nets can accidentally entangle and
injure or drown dolphins.
17. CONSERVATION
The International Whaling Commission
IUCN/The World Conservation Union Species Survival Commission
(SSC)
The Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES)- listed in appendix II
The Marine Mammal Protection Act (MMPA)
U.S. Dolphin Protection Consumer Information Act (DPCIA)
Marine life Parks
The SeaWorld & Busch Gardens Conservation Fund
18. IWC- To protect small cetaceans and whales Seaworld created nutritional formulas
for orphan animals
The non-profit SeaWorld & Busch Gardens Conservation Fund(SWBGCF) is committed to species
research, habitat protection, animal rescue, and conservation education.
