Marine Mammals

Example marine mammals: Seals, Sea Lions, Walruses, Otters, Manatees, Polar Bears, Dugongs, Whales, Dolphins

• Homeotherms

• Body temperature stays at a constant level
• Most marine mammals have a thick layer of blubber to keep body temp warm

• Reproduction: Viviparous

• Live birth: Offspring develops inside the body before birth

• Mammary glands

• Females produce milk containing essential nutrients for the offspring

• Sexual Dimorphism

• Males and females look different

• Examples: Size, Color, etc

• Order: Pinnipedia

• "fin-footed"
• Seals, sea lions, walruses

Anatomy of a Seal

Anatomy of a Sea Lion

• Seal and Sea Lion Diet

• Carnivores (meat eaters)
• Fish, squid, octopus, crustaceans, and occasionally other pinnipeds

Characteristic	Seal	Sea Lion
Ears	Ear holes	Ear flaps
Front Flippers	Stubby front flippers with claws on each toe	Elongated front flippers without claws
General Body Shape	More streamlined	More agile
Where They Hang Out	Spend most of their time in the water	Bask in the sun
On Land	Galumph: ‘belly crawlers’	Walk
Walking	Can't	Sea lions are able to ‘walk’ on land more easily because they can rotate their hind flippers underneath their bodies.
Vocalization	Grunt/chirp	Bark
Socialization	Solitary and shy towards humans	Gather in large groups called rafts or herds of up to 1,500 animals

Walruses

• Characteristics

• Large, Robust Body
• Reddish-Brown coloration
• HUNDREDS of vibrissae (whiskers)
• Both male and females have large tusks

• Diet

• Mainly eat bivalve mollusks (clams, oysters) and other invertebrates like marine worms, snails, sea cucumbers, squid, and crab

Order: Carnivora

• Sea otters and polar bears
• Sea otters

• Characteristics

• Very fine, dense fur coats with 2 layers. (one for warmth and one oily top coat to keep water away from the skin)
• Small front feet with retractable claws
• Flipper-like, broad and webbed back feet

• Diet

• urchins, abalone, mussels, clams, crabs, snails
• eat approximately 25% of their weight in food each day
• males can weight up to 100lbs

• Keystone species

• Keystone Species: A species whose role in the environment is essential for maintaining structure and function in an ecosystem
• Sea otters prey on the species that would otherwise destroy kelp forests.

• Kelp forests provide food and shelter for many different marine species.

• Other facts

• While sleeping, sea otters hold hands so that they do not drift apart from one another
• A group resting together is called a raft
• Sea otters have pockets under their arms where they keep their ‘favorite rock’ which they use as tools to open and eat shells

• Polar Bears

• Characteristics

• Order: Carnivora
• Largest land carnivore
• Spend most of time on ice, but depend on the ocean to survive
• Males (800-1500 lbs) are significantly larger than females (300-550 lbs)

• Adaptations for cold weather

• Fur and skin

• The hair of a polar bear is actually hollow and TRANSLUCENT
• Their skin is BLACK. (To attract sunlight for warmth)
• It only appears white due to the way light reacts with their fur
• This helps them to blend in with their surroundings

• Feet

• Thick padding on feet to insulate from cold
• Wide paws and hair between pads on paws to prevent from slipping

• Tiny ears

• To reduce heat loss

• Adaptations for aquatic life

• Claws and strong legs to help swim and catch prey

• Diet

• Seals, whale carcass, beluga
• They do NOT typically eat fish

• Breeding

• Females breed once every 3 years
• They are pregnant for 8 months
• Most common litter size: 2
• Cubs stay with mom for ~30 months

Order: Sirenia

• Manatees and dugongs

• Characteristics

• Large body
• Completely aquatic (never on land)
• Tough thick skin with little hair
• No hind limbs
• Flattened tails
• Nostrils on top of snout with nasal plugs
• Mammary glands located in ‘armpits’

• 4 species remain

• Endangered or Threatened

• Amazonian Manatee
• West African Manatee
• West Indian Manatee
• Dugong

• Extinct

• Steller's Sea Cow

• Steller’s sea cow went extinct in the 1700s due to overhunting
• Measured 30 ft long

• Diet

• Herbivores
• Only eat PLANTS

Characteristic	Manatee	Dugong
Feeding	feed at all water depths	feed exclusively on what is at the bottom of the water
Tail	Rounded tail	Dolphin-like fluke
Nails	have nails on forelimbs	do not have nails
Teeth	Replace their teeth throughout their lives Teeth are lined along sides of mouth All molars	Two tusks used for digging up plant roots Teeth rounded and peg like Teeth do not grow back
Mouth	Short snout	Broad downward- facing trunk-like snouts
Life Span	~50 years	~70 years
Size	Larger (11 feet)	Smaller (8 feet)
Location	Tropical Atlantic and Pacific	Indian Ocean and Western Pacific
Reproduction	Females: Produce 1 calf every 2-5 years Males: have several female partners	Females: Produce 1 calf every 3-7 years Males: are monogamous

Biggest threat: Sirenias are often injured by the propellers of boats