Marine MammalsMarine Mammals

Chapter 10

Mammals:Mammals:1. Have a four-chambered heart2 Females have mammary glands2. Females have mammary glands3. Have hair

Order: CetaceansOrder: Cetaceans

• There are about 80 different speciesThere are about 80 different species• Include whales, dolphins, and porpoises• The difference between dolphins andThe difference between dolphins and

porpoises is that dolphins have an elongated snout and can swim faster.

• Two main groups of whales:baleen whalesba ee a estoothed whales

• Pod: group or family of whalesPod: group or family of whales

Baleen Whales• Belong to suborder Mysticeti• Are filter feeders that eat plankton and smallAre filter feeders that eat plankton and small

fish• They include such species as the blue, y p ,

finback, humpback, right, and gray whaleBlue whale: the biggest animal that has ever gg

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 zooplanktonstrain the small zooplankton

• Gray whale (bottom feeder) suck up sediments on the seafloor and then filter out and eat small

t d th ll i t b tcrustaceans and other small invertebrates

• Belong to suborder

Toothed Whales Odontoceti• Include sperm, killer,

pilot, and beluga whales as well as d l hi ddolphins and porpoisesHave peglike teeth on• Have peglike teeth on their jaws to catch their prey: fish sealstheir 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; g g

• The smallest is the narwhal – 5 meters long• Sperm whale has large cone-shaped teethSperm whale has large cone shaped teeth

but only on its long narrow lower jaw• The male narwhal has an elongated front e a e a a as a e o gated o t

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 Whalesp• Cetaceans are fully aquatic animals; they do

not return to land to breednot return to land to breed• Gestation period may last from about 11

months to as long as 18 months in the glargest 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 breathg

• Female nurses her calf from 6 to 10 months• Whales milk is rich in protein and fatWhales milk is rich in protein and fat

•Blue whale feeds her calf the equivalent of 400 glasses of milk a dayof 400 glasses of milk a day

Adaptations and BehaviorspBreathing:• Whales breathe through an opening on the• Whales breathe through an opening on the

top of their heads – blowhole – which is its nose or nostrilsnose or nostrils

• Toothed whales have one nostril; baleen whales have two nostrilsa es a e t o ost s

Swimming:• Killer whales are the fastest of all the marine• Killer whales are the fastest of all the marine

mammals, being clocked at 55km/hr.• Vigorous contractions of its body muscles• Vigorous contractions of its body muscles

cause the up-and-down movement of its hind flippers called tail flukes.pp

• 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;• Diving: used to capture prey around them;

produce a wall of bubbles to confuse and entrap their prey. Whale then swims up andentrap 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 g yunderstood 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 g p p yout of the water and then crashes back down, creating a huge, loud splash.

reasons: dislodging of skin parasitesform of communicationplayful 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 thickthe skin. May be more than 60cm thick.

Sperm Whale• The deepest diving whale; dives for its

f itfavorite prey• Has been found at a depth of 1127m;

although it is believed that they may actuallyalthough 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 abilityability.

• Increase the density of the oil before they dive and decrease its density when theydive 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 EcholocationD l hi i t th h i f• Dolphins communicate through a series of clicks and other soundsSounds are produced in the dolphin’s airway• Sounds are produced in the dolphin’s airway and then directed by a fatty bump on its head called the meloncalled the melon

• Dolphins and whales use sound waves to sense objects in their environment and tosense 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 vocalizey

• 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• 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 shorelinewhales 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-tidefluids), DDT, and biotoxins (from red-tide flagellates)

Other Marine Mammals

Seals and Sea Lions• Classified in suborder Pinnipedia (“wing-

foot” or “fin-foot”))• Includes seals, sea lions, and walruses• About 30 different species; found throughout p ; g

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 llarger prey

Seals vs. Sea Lions• Forelimbs of sea lion are longer and moreForelimbs of sea lion are longer and more

developed than seal• Sea lion uses its forelimbs to move quicklySea 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 l t d f dlocated food

Walrus• Inhabits the frigid Arctic and sub ArcticInhabits the frigid Arctic and sub Arctic

waters• Tusks are overly developed canines used forTusks 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 OtterCl l l t d t l d i k• Closely related to weasels and minks

• Only recently became adapted to living in the ( b t 3 000 000 A )ocean (about 3,000,000 yrs. Ago)

• Smallest of the marine mammals; grow to about one meter in legthabout one meter in legth

• 3 main populations live in the Pacific: along the coasts of California Alaska and thethe coasts of California, Alaska, and the Aleutian Islands, and various Russian islands

• Commonly found in the giant kelp forest along the rocky California coastg y

• They eat, mate, sleep, and rear their young in the waterthe water

• Have no blubber under their skin; but retains its heat from its incredibly thick furits heat from its incredibly thick fur

Threats:• Oil spills from tankers coats their fur which• Oil spills from tankers coats their fur, which

they cannot clean and causes them to freeze due to lack of insulationdue to lack of insulation

• Fur was prized by trappers in the 1800’s• Prey to great white sharks and killer whalesPrey to great white sharks and killer whales

Manatees and Dugongs• Lives in the warm shallow waters of Florida• Lives in the warm, shallow waters of Florida• Also found in the shallow waters of the

Caribbean in the Amazon River and alongCaribbean, 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 15minutesy

• 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 plantsy g q p

• Adults consume up to 45kg of vegetation/day• Commonly referred to as the sea cowCommonly referred to as the sea cow• Dugong is a close relative• Both classified in the order Sirenia• Both classified in the order Sirenia• Distant relatives of the elephant• Uses its upper lip prehensile lip to grasp• Uses its upper lip, prehensile lip, to grasp

vegetation• Found in the tropical Pacific and off the east• Found in the tropical Pacific and off the east

coast of Africa• Its tail is triangular rather than roundedIts tail is triangular rather than rounded

Reproduction in Pinnipeds• Have to return to land to mate and give birthHave to return to land to mate and give birth• Congregate by the thousands during

breeding seasong• Mature males fight for access to females;

male acquires “harems”

Polar Bears• Most terrestrial marine mammalMost terrestrial marine mammal• Live on ice floes and along the shore in the

North Polar regionNorth Polar region• Have dense fur and thick layer of blubber;

hairs are hollow which help in retaining heata s a e o o c e p eta g eat• 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 ResponseThe Diving Response

• Marine mammals can dive to great depths onMarine mammals can dive to great depths on a single breath because they have adaptations that increase their oxygen-carrying 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

lungslungs

brainmuscles

heart

• The ability to inhale and exhale quickly; elastic tissue in their lungs and chest gpermits greater expansion during inhalation

• Diving mammals have a higher blood volume g gand a greater concentration of oxygen-binding RBC’s than nondiving mammals

• Possess myoglobin, oxygen-binding protein. Together with hemoglobin, they increase the

i it f th i b dioxygen-carrying capacity of their bodies• Can slow their heart rate - bradycardia

Depth and Time of Breath-Hold in Diving Marine Mammals

Mammal Depth ( t )

Maximum Breath Hold

Mammals

(meters) Breath Hold (minutes)

Sea otter 55 5Sea otter 55 5

Porpoise 305 6p

Sea lion 168 30

True seal 575 73

Sperm whale 2200 90