Chapter 14
WHAT IS A MARINE MAMMAL? Member of Class: MAMMALIA All possess major adaptations that allow them to live in the water (to a greater or lesser extent) Some marine mammals live entirely in the marine environment, others may come on land for part of their lives However, all marine mammals derive all (or most) of their food from the marine environment
POLAR BEAR Ursus maritimus
SEA OTTER Enhydra lutris
SIRENIANS - Manatees and dugongs
PINNIPEDS - Seals, sealions and walruses
CETACEANS Whales, dolphins and porpoises
To be classified as a mammal Must posses all five characteristics Lungs and breath air. Are warm blooded and maintain a constant body temperature. Most bear live young. One primitive mammal group, the Monotremes (which includes the duckbill platypus and the echidna) lays eggs. Produce milk and nurse their young. Have hair at some point in their lives
14.1 Cetaceans: Whales and Dolphins and porpoises Cetacean pronounced si-tey-shuhn The largest cetaceans are the whales the smallest cetaceans are dolphins and porpoises, which are actually small whales that range from 2-4m in length
14.1 Cetaceans: Whales and Dolphins and porpoises Dolphins & porpoises SIMILARITIES? both very intelligent & social Both display a variety of acrobatic leaps, spins & somersaults out of water and into the air DIFFERENCES? Dolphins have elongated snout and swim faster
2 main classes of whales: baleen and toothed Baleen Whales: filter feeders with baleen plates; eat zooplankton and small fish Suborder Mysticeti Include species Blue Whale biggest animal to ever live on earth Finback Whale Humpback Whale Right Whale Gray Whale
The Baleen whales all possess hundreds of plates of baleen instead of teeth. Baleen is made of keratin and hangs from the upper jaw. The fringed baleen plates trap engulfed prey and filter out water. Throat of some baleen whales (Rorqual) is pleated like an accordion to expand and hold the large amounts of water
Types of feeding methods in Baleen whales Rorquals take huge gulps of water to get krill and small fish Right whales swim slowly through nearsurface waters with their mouths held open to skim and strain the small zooplankton Bottom feeders such as the gray whale suck up sediments on the seafloor and then filter out and eat small crustaceans and other invertebrates
2 main classes of whales: baleen and toothed Toothed Whales: hunters with peglike teeth; eat fish, squid, penguins, and seals - Suborder Odontoceti - Include species - Sperm - Killer - Pilot - Beluga - narwhal - Dolphins and porpoises
Toothed whale feeding Active hunters for fish, seals, penguins, squid Usually swallows it whole Compartments in the stomach chew and digest the food
Toothed whales Largest: sperm whale - 15m length - Cone-shaped teeth on long, narrow lower jaw Smallest (not counting dolphins and porpoises) is the narwhal -5m in length -elongated front tooth grows out of the left side of its jaw -tusk used at breeding time to attract females and to fend of rival males
Reproduction in Whales Fertilization & development are internal Gestation period (period of embryonic development) is 11 to 18 months Breed about once every 3 years Give birth to one calf Mother invest great deal of parental car Close bond develops between mother and calf Nurses calf 6 to 10 months Milk rich in protein & fat (50%) helps the newborn grow fast and add on layers of insulating fat
14.1 SR
14.2 Whales Adaptation and Behaviors Blowhole: (nose or nostril) in whales and dolphins, opening on top of head used for breathing - As early whales became more fully aquatic, their nostrils moved from front (snout) to the top of the head but must surface to breath Toothed whales have one nostril; Baleen whales have two nostrils Breath in air, carried to lungs, and exhale through blowhole
Killer whale, or orca Swimming in Whales Fastest of all marine mammals 55km/hr Tail flukes: in cetaceans, hind flipper used to propel animal through the water Dorsal fin used to stay on course Pectoral fins used for steering, braking, & balance
Other Movements in Whales Lobtailing: behavior in which whales wave and smash tail on ocean surface May be a sign of aggression or announcing its presence Spyhopping: behavior in which whales rise head above water to look around
Diving: most common activity of whales. Use pectoral fins to change position from horizontal to vertical. The tail flukes are the last part out of the water Breaching: behavior in which wales leap out of water and crash back down Might be a means of dislodging skin parasites Form of communication Or just playful behavior
Whales are longdistance swimmers Travel with extended family group or pod Can cover thousands of kilometers Many migrated between feeding and breeding grounds Feed and breed in cold water (Arctic or Iceland) Give birth in warmer water (California or Caribbean Sea) Whale Migration
Keeping Warm in Cold Water Blubber: in cetaceans and pinnipeds, a thick layer of fat under the skin 60cm thick Traps and prevents body heat from being lost - Babies lack the fat layers of adults so it is most adaptive for them to be born in the warmer water
Communication and Echolocation in Whales Melon: in dolphins, a fatty bump on forehead that focuses sounds in the head Echolocation: in cetaceans, a natural form of sonar used in communication and hunting
Communication and Echolocation in Whales Stranding: a behavior in which whales become beached (and die) along shores Internal organs crushed by their own body weight Possible disease, parasites, or infection disorients leader of pod along shoreline Man made toxins in water from PCB, DDT Biotoxins from red-tide
14.2 SR
14.3 Seals and other Marine Mammals Carnivores: sea otters and polar bears Herbivores: term that describes planteating animals; usually have blunt teeth
Seals and Sea Lion Pinnipeds: seals, sea lions and walruses Pinnipeds mean wing-foot 30 different species Seals and sea lions have widest distribution and inhabit all oceans Sea lions have longer forelimbs used to move through water and used prop itself up on land, also have external ear flaps Seals can only drag its body along the beach Both have whiskers Feed on fish squid mollusks, crustaceans
Reproduction in Pinnipeds Pinnipeds breed on land Females give birth and nurse on land Mature males right for access to females Dominant males acquire harems of females they mate with Seals and sea lions have ability to delay embryonic development so birth occurs exactly 12 months after mating when they come ashore again to breed
The Walrus Walruses only found in polar seas of north Arctic Walruses can dive 90 meters deep to find food Tusks are overly developed canines found both in male and females Used for digging up mollusks on seafloor and hauling walrus up onto ice
Adaptations of Pinnipeds Not fully aquatic Intelligent & social Communicate using a variety of sounds Ability to dive to great depths Deepest diver is the elephant seal 1500 m Layer of blubber and seals and sea lions are covered with dense fur Seals and sea lions have been hunted for their fur and walruses for their ivory tusks
The Sea Otter Sea Otter: only recently adapted to living in the ocean 3 million yrs. Ago Related to weasels and minks Smallest of marine mammals 1 meter in length 3 main population life in Pacific along coast of California, Alaska & Aleutian Island & Russian islands
The Sea Otter Found in kelp forests holding onto the kelp to anchor themselves in choppy water Efficient swimmers and divers with webbed hind feet, flattened tail and streamlined body Eat mussel, crab, abalone, sea urchin, fish and snails While floating on back on surface of water they use rocks to open the shell fish
The Sea Otter Spend most of their life in the ocean Eat, sleep, mate and rear their young in the water May go ashore at low tide to look for mollusks Have no blubber but retain body heat because of very thick fur which is constantly groomed with oil from its skin
Threats to Sea Otters Oil spills devastate them because they can not clean their fur, otters will freeze due to insulation loss In 1800s otter was almost hunted to extinction for its prized fur Today they are protected and making a comeback
Threats to Sea Otters California population less then 2500 otters Russian and Alaskan population better at 20,000 and 120,000 otters Sea otters also at risk of predation by great white shark & orca Also there is a rive otter that lives in fresh water and are found in Europe, North and South America Also need protections due to loss of habitat, pollution, and hunting
Manatees and Dugongs Manatee a docile marine mammal, lives in warm shallow waters of Florida Live under water, feed on vegetation About every 15 they surface for air Social animal, communicate using highpitched squeaks and whistles
Manatees and Dugongs Winter manatees stay in warm coastal rivers Summer migrate to warm ocean waters along coasts Also found in Caribbean, Amazon River, and along Atlantic coasts of South American and West Africa
Manatees and Dugongs Manatees move slowly in water propelled by gentle up-and-down movement Have no hind limbs and forelimbs used for feeding Consume up to 45 kg of vegetation a day Reach over 900kg body weight Referred to as the sea cow
Manatees and Dugongs Dugong is closely related to the manatee Classified in the order of mammals called Sirenia named for mythical female sirens Distant relative of the elephant Dugongs found in tropical Pacific and off the east coast of Africa
The Polar Bear Most terrestrial marine mammal Lives on ice floes along shore in North Pole Has dense fur and thick layer of blubber Excellent swimmer with powerful forelimbs, not fast enough in the water to catch a seal, must do that on land
The Polar Bear Polar bears prefer seal but also ear fish, birds, and plants Polar bears are solitary animals with the exception of mother bears with her cubs
Homework page 350 1-3
14.4 The Diving Response Diving marine mammals can dive to great depths on a single breath because they can increase the oxygen-carrying capacity of their bodies Dive response is the detouring, or shunting, the blood that contains nutrients and oxygen from the rest of the body to only vital organs brain, heart, lungs, and muscles
Other Diving Response Adaptations Marine mammals can inhale and exhale quickly and completely between dives Elastic tissue in their lungs and chest permit greater expansion Higher blood volume and greater concentration of oxygen-binding red blood cells than nondiving mammals
Other Diving Response Adaptations Diving mammals also possess oxygenbinding proteins called myoglobin located in their muscles Bradycardia: in diving marine mammals, ability to slow the heart rate during deep dives; important part of diving response Ex. Elephant seal can drop heart rate from 85 to 12 beats per minute
Other Diving Response Adaptations Diving responses involve reflex action of nervous system water pressure acts on pressure receptors located in head of animal send impulses to brain Brain sends impulses back to heart, regulates its rate Impulse from brain also sent to blood vessels, causing them to constrict or dilate
Homework page 352 1-3