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.
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.