Whales, Dolphins, Porpoises

Phylum Chordata, Class mammalia, Order Cetacea

Cetaceans are grouped on basis of their mouths:  Mysteceti - Whales with baleen (strainers) for plankton: Both nostrils have a blow hole  Odontoceti - whales, dolphins, and porpoises with teeth; carnivores; 2 nostrils but only one blow hole; smaller in size

Marine Mammal Characteristics:  Hair (at birth)  Nurse Young  Breathe Air  Warm Blooded  Placenta  Horizontal Tail ( All marine cetaceans)

The Blue Whale 100 feet long 150 tons The largest mammal alive.

Narwhal The Tusk is an 8 foot left tooth and found only in males.

Beluga Whales Pure white, Arctic whales. Called “sea canaries” due to their vocalizations.

Dolphins  The most intelligent whale.  Body temp is a constant 97.7 F  Average of 7 min. between breaths.  Swims at 25 miles per hour.

Whales and all marine mammals are protected by the Marine Mammals Protection Act of 1972.

Cetacean Adaptations In the Marine Habitat

Swimming  Powerful tail flukes  Fluke markings are used as ID  Sei whales are the fastest swimmers - 40 mph

Digestion  Multi-compartmentalized stomachs ‘chew’ food. Teeth are conical and unspecialized.

Digestion  Baleen Whales feed by jumping through pockets of plankton (breaching)  Stomach can hold 2 tons of krill at one time.

Digestion  Toothed whales often hunt in packs and seek out individual fish, penguins, seals, sharks or other whales.

Cetacean II The Journey Continues

Circulation  High Blood volume holds max. oxygen and glucose levels. Their veins are large enough for a trout to swim through.  Blood can be shunted to brain, heart, lungs and muscles and away from stomach and kidneys to protect vital organs.  A 4 chambered heart can transfer arteriole heat to the veins as blood flows toward the tail – called counter –current heat exchange.

Circulation Cont.  Blubber insulates against cold. Overheating is solved by sending blood to surface tissues ( flukes and fins) and bypassing the countercurrent vessels.  Whales in captivity exercise less and often lose the ability to cool off by straightening the fins.

Senses  Vision is poor in most species  Vocalizations and echolocation compensates.  Whales have no vocal chords but make songs, clicks and whines by vibrations in the blow hole.

Communication  Indicate territories  Attract mates  Act as homing device for young.  Families of whales have their own dialect.  Sounds are emitted and amplified in the head through an oil filled cavity called a melon.

 Incoming vibrations are focused through the jaw and melon to the inner ear and the brain.  The sounds are extremely accurate and very loud- can be used to stun prey.  When whales enter the thermocline, sounds can be heard ¼ of the distance around the earth.

Diving  Lungs are completely filled and emptied quickly through the blow hole on top of the head.  Trachea under the blow hole connects directly to lungs.  Cannot breathe through their mouth and can drown unless the top of the head is exposed to air.

 Nasal passage closes when relaxed to prevent water from entering the lungs, and allows them to sleep for short periods without drowning.  Some whales go to depths of 13,000 ft. and only breath every 90 minutes – smaller species have less range.  Oxygen is stored in the muscles. Ribs are collapsible to reduce internal air pockets.

Excretory  Specialized kidneys allow whales to drink salt water. The urine is very saline.

Reproduction  Mating usually occurs in early summer.  Implantation of the egg is delayed 4 months. Gestation lasts 7 months, so babies are born in warm summer months.  Many whales only have one calf every 2-3 years. Babies range in weight from 200 pounds to 1 tone.