Dolphins and porpoises

An interactive lesson By: Lindsey Redden

Some Pictures of Bottlenose Dolphins

Dolphin vs. porpoise

• Dolphin Porpoise

Porpoises

• Family Phoecoenidae

• No distinct beak or rostrum

• Spade shaped teeth

• Smaller than most dolphins

Vaquita

• Smallest cetacean

• Only found in the Gulf of California

• One of the most endangered cetaceans.

• Only 600 left

• Dolphin Family Delphinidae

• Larger

• Conical teeth

• Distinct beak or rostrum

• 37 species

Dolphin’s Head

• Well defined rostrum (snout)

• Conical interlocking teeth designed for grasping

• 71-104 teeth

• Eyes are on the side of the head near the corners of the mouth

• Ears are located behind the eyes. Small openings with no external flap

DOLPHIN SENSES

• EXCELLENT VISION IN AND OUT OF WATER

• Eyes have rods (black and white) and cones (color vision)

• Skin is sensitive to touch

• Have taste buds

• No olfactory bulb, possibly no sense of smell

DOLPHIN SWIMMING

• Regularly swim at 3 - 7 mph

• Burst of up to 40 mph

• Regularly dive 10 - 150 feet

• Deepest trained dive up to 1,800 feet

• Average of 1 - 6 breaths per minute

• Dives can last 8 - 10 minutes

ADAPTATIONS FOR DIVING

• Heartbeat is reduced• Blood is directed to vital organs (heart,

lungs, and brain)• Muscles have myoglobin, which stores

oxygen and helps prevent oxygen deficiency

DOLPHIN RESPIRATION

• A dolphin exchanges 80 - 90 % of the air in its lungs with each breath (humans exchange 17%)

• Dolphins inhale and exhale in less than 2 seconds

DOLPHIN SLEEP

• Dolphins are conscious breathers. They have to think to breathe.

• Dolphins sleep with one hemisphere of the brain at a time. They are never completely unconscious, so they can still breathe.

• In the first attempts at dolphin surgery, the dolphins died because they stopped breathing..

DOLPHIN BODY REGULATION

• Body Temperature is 98.4 0F

• Body Fat is about 18 - 20 %

DOLPHIN SOCIAL ORGANIZATION

• Live in groups called pods (2 - 20 in pods)

• Pods are based on age, sex, and familial relations

• Mature females and offspring

• Mature males and sub adult males

• Hunt together in teams

• Have dating rituals and friendships

Social Behavior

FOODFOOD

• Eat fish, squid, and crustaceans

• Eat 4 - 6% of body weight daily

• Do not chew their food but swallow it whole head first so spines won’t catch in their throat

REPRODUCTION

• Gestation is 12 months

• Usually give birth to 1 calf every 2 years

• Dolphin milk is 17% fat, (humans and cows are about 4.5%)

ECHOLOCATION IN DOLPHINS

• Air sacs - make clicks

• Melon - focuses clicks

• Lower jaw - detects returning sounds

ECHOLOCATION IN DOLPHINS page 2

• Used to sense landscape in the dark

• Used to locate prey

• May be used to locate one another

• May be used to stun prey

• Works like sonar

Dolphin Intelligence

• Have a brain structure similar to humans

• Can process the complexities of social relationships when living in organized groups

• Have a large number of interconnections between neurons

INDICATIONS OF DOLPHIN INTELLIGENCE

• Can learn languages and respond correctly to sentences never uttered to them before ex. Frisbee fetch hoop

• Can rearrange environment to follow a command ex. Swim through a hoop, but hoop is on the bottom of the pool

Baiji (Chinese river dolphin, Yangtze river dolphin)

• Lived only in the Yangtze river

• Last seen in 2004• An intensive search

in 2006 found no individuals.

• They were killed by illegal fishing, collisions with boats, and water pollution.

Amazon river dolphin

• Lives only in the Amazon river

• Color ranges from blue to grey to pink

Bottle nosed dolphin

• Found in most tropical and subtropical areas.

• Have many complicated behaviors and hunting techniques.

• Hunt cooperatively with humans in Brazil.

Various Dolphin species

Japanese Dolphin Hunt

• Every year Japanese fisherman kill thousands of dolphins in coastal bays.

• This is done from a belief that the dolphins compete with the fisherman for fish.

• The dolphins are usually sold for their meat, and some are used in marine parks.