Marine Mammals Chapter 10
Mammals: 1. Have a four-chambered heart 2. Females have mammary glands 3. Have hair
Order: Cetaceans There are about 80 different species Include whales, dolphins, and porpoises The difference between dolphins and porpoises is that dolphins have an elongated snout and can swim faster. Two main groups of whales: baleen whales toothed whales Pod: group or family of whales
Baleen Whales Belong to suborder Mysticeti Are filter feeders that eat plankton and small fish They include such species as the blue, finback, humpback, right, and gray whale Blue whale: the biggest animal that has ever lived on Earth even bigger than the largest dinosaurs Measures 30 meters long and weighs in at 150,000 kg
Three types of feeding methods in baleen whales: Rorquals ( furrow whales ) take huge gulps of water to get krill and small fish Right whales swim slowly through near-surface waters with their mouths held open to skim and strain the small zooplankton Gray whale (bottom feeder) suck up sediments on the seafloor and then filter out and eat small crustaceans and other small invertebrates t
Toothed Whales Belong to suborder Odontoceti Include sperm, killer, pilot, and beluga whales as well as dolphins and porpoises Have peglike teeth on their jaws to catch their prey: fish, seals, penguins, and squid; usually swallow their prey whole
Sperm whale is the largest of the toothed whales; ;grows to about 15 meters in length The smallest is the narwhal 5 meters long Sperm whale has large cone-shaped teeth but only on its long narrow lower jaw The male narwhal a has an elongated front tooth that grows out of the left side of its upper jaw; used at breeding time to attract females and fend off rival males
Reproduction in Whales Cetaceans are fully aquatic animals; they do not return to land to breed Gestation period may last from about 11 months to as long as 18 months in the largest whales. Breed about once every 3 years and usually give birth to one calf at a time Born tail first
Newborn whale is pushed by its mother to the surface to get its first breath Female nurses her calf from 6 to 10 months Whales milk is rich in protein and fat Blue whale feeds her calf the equivalent of 400 glasses of milk a day
Adaptations and Behaviors Breathing: Whales breathe through an opening on the top of their heads blowhole which is its nose or nostrils Toothed whales have one nostril; baleen whales aeshave etwo nostrils s
Swimming: Killer whales are the fastest of all the marine mammals, being clocked at 55km/hr. Vigorous contractions of its body muscles cause the up-and-down movement of its hind flippers called tail flukes. Pectoral fins are used for braking, steering, and balance Inside the pectoral fins are bones that are similar in structure to its land-dwelling ancestors.
Other Movements in Whales: Diving: used to capture prey around them; produce a wall of bubbles to confuse and entrap their prey. Whale then swims up and engulfs its prey lunging. Lobtailing: waving its tail in the air then smashing it on the ocean surface. Not fully understood by scientists. Some believe its aggression or announcing its presence.
Skyhopping: whale raises its head above the water s surface to look around for a few seconds. Breaching: whale leaps almost completely out of the water and then crashes back down, creating a huge, loud splash. reasons: dislodging of skin parasites form of communication playful behavior
Are endothermic Able to keep warm in the frigid polar seas; blubber thick layer of fat that traps and prevents body heat from being lost through the skin. May be more than 60cm thick.
Sperm Whale The deepest diving whale; dives for its favorite prey Has been found at a depth of 1127m; although it is believed that they may actually dive to more than 3x that depth. Name is derived from the fact that it has a white waxy oil in its head spermaceti which plays an important role on its diving ability. Increase the density of the oil before they dive and decrease its density when they ascend Spermaceti was used in the manufacture of candles and as a lubricant for watch parts and delicate machinery
Communication and Echolocation Dolphins communicate through h a series of clicks and other sounds Sounds are produced in the dolphin s airway and then directed by a fatty bump on its head called the melon Dolphins and whales use sound waves to sense objects in their environment and to locate prey Echolocation: natural form of sonar where sound is bounced of objects
Sperm whales use a pattern of clicks known as codas Belugas produce a variety of sounds when they vocalize Humpback whales produce songs apparently by the breeding males and is related to competition for mates
Stranding: behavior in which become beached (and die) along shores Their internal organs become crushed by their own weight Even after towing them back to the waters, some whales swim back to the beach and strand themselves again Reasons: Disease, parasites, or an infection may cause whales to become disoriented along a shoreline Toxins from water pollution as well as natural toxins have been found in stranded dolphins tissue Toxins include PCB( coolants and insulating fluids), DDT, and biotoxins (from red-tide flagellates)
Other Marine Mammals
Seals and Sea Lions Classified in suborder Pinnipedia ( wingfoot or fin-foot ) Includes seals, sea lions, and walruses About 30 different species; found throughout the world Seals and sea lions inhabit all the oceans; walruses are found only in the polar seas of the north Main source of food are fish and squid; some will eat mollusks, crustaceans, or much larger prey
Seals vs. Sea Lions Forelimbs of sea lion are longer and more developed than seal Sea lion uses its forelimbs to move quickly through water; it can prop itself up and move quickly through land; seal can only drag its body awkwardly along the beach Seal propels itself swiftly through the water using its strong hind flippers Sea lions have external ear flaps; seals do not Both have stiff facial whiskers used in located food
Walrus Inhabits the frigid Arctic and sub Arctic waters Tusks are overly developed canines used for digging up mollusks from the seafloor and for hauling itself up onto the ice; found in both males and females In males, tusks are longer and used to determine dominance Use their sensitive, stiff facial whiskers to locate clams and mussels
Sea Otter Closely l related to weasels and minks Only recently became adapted to living in the ocean (about 3,000,000 yrs. Ago) Smallest of the marine mammals; grow to about one meter in legth 3 main populations live in the Pacific: along the coasts of California, Alaska, and the Aleutian Islands, and various Russian islands Commonly found in the giant kelp forest along the rocky California coast
They eat, mate, sleep, and rear their young in the water Have no blubber under their skin; but retains its heat from its incredibly thick fur Threats: Oil spills from tankers coats their fur, which they cannot clean and causes them to freeze due to lack of insulation Fur was prized by trappers in the 1800 s Prey to great white sharks and killer whales
Manatees and Dugongs Lives in the warm, shallow waters of Florida Also found in the shallow waters of the Caribbean, in the Amazon River, and along the Atlantic coasts of South America and West Africa Lives underwater, feeding on vegetation; surfaces for a breath of air every 15minutes Social animals; communicate using a variety of high-pitched squeaks and whistles Moves slowly through water propelled by a gentle up-and down movement of its paddlelike tail
Has no hind limbs and its forelimbs are mainly used for holding onto aquatic plants Adults consume up to 45kg of vegetation/day Commonly referred to as the sea cow Dugong is a close relative Both classified in the order Sirenia Distant relatives of the elephant Uses its upper lip, prehensile lip, to grasp vegetation Found in the tropical Pacific and off the east coast of Africa Its tail is triangular rather than rounded
Reproduction in Pinnipeds Have to return to land to mate and give birth Congregate by the thousands during breeding season Mature males fight for access to females; male acquires harems
Polar Bears Most terrestrial marine mammal Live on ice floes and along the shore in the North Polar region Have dense fur and thick layer of blubber; hairs are hollow o which help in retaining heat Streamlined head and body making it an excellent swimmer Favorite food: seals; will also eat fish, birds, and plants, depending on the season
The Diving Response Marine mammals can dive to great depths on a single breath because they have adaptations that increase their oxygencarrying capacity of their bodies Diving response (diving reflex): group of structural and behavioral responses that enables deep diving
Detouring of blood that contains glucose and oxygen from the rest of the body to the vital organs lungs brain muscles heart
The ability to inhale and exhale quickly; elastic tissue in their lungs and chest permits greater expansion during inhalation Diving mammals have a higher blood volume and a greater concentration of oxygenbinding RBC s than nondiving mammals Possess myoglobin, oxygen-binding protein. Together with hemoglobin, they increase the oxygen-carrying capacity of their bodies Can slow their heart rate - bradycardia
Depth and Time of Breath-Hold in Diving Marine Mammals Mammal Depth (meters) Maximum Breath Hold (minutes) Sea otter 55 5 Porpoise 305 6 Sea lion 168 30 True seal 575 73 Sperm whale 2200 90