What are the things that make a marine mammal a mammal?
Breath air through lungs
Also, usually large brains and different shapes and sizes of teeth
How is it that these mammals are able to survive in a marine environment?
for life in a wet, cold and salty place.
Streamlined body to reduce drag
Powerful, efficient appendages
Efficient use of O2 in lungs
O2 is stored in blood (myoglobin) and muscles
Voluntary and conscious breathing
Collapsible lungs, thick cartilaginous trachea to
tolerate pressure changes
High tolerance to lactic acid- muscles can work anaerobically
Large body, small surface-to volume ratio reduces heat loss
Blubber and/or underfur
Complex circulatory system conserves and dissipates heat
Use freshwater from food, inhaled air and blubber
Remove salts from bodies using many small kidneys
Marine Mammal Evolution
Life evolved in sea 3 billion years ago
Ancestors in and out of sea, on and off of land as food was available.
Whales and dolphins share a common ancestor with sheep, cows, pigs, giraffes? Related to hippos?
Manatees relatives of elephants?
Seals relatives of bears or canines ?
Evolution of a Seal
Evolution of a Whale
Feet to Flippers-
Front legs became paddle-like for steering
Hind legs disappeared
Nostrils to Blow hole-
Moved to the top of the head and became blowholes
Quick breathing while swimming
Tail to Fluke-
Animal tail widened into horizontal flukes for swimming
Became sleek and torpedo-shaped “streamlined” for movement through water
Air is precious and in short supply while diving.
A seal’s heart rate slows
when diving and blood
is directed away from
extremities towards heart,
lungs and brain.
Whales have double
the amount of blood
and # of red blood
cells than land
Cold is a problem for many marine mammals - water conducts heat 25x faster than air. *Blubber to insulate and streamline *Blubber as stored energy Seals have braided arteries so that cold blood is warmed. Some whales have blubber 20 inches thick!
Found in North Pacific and North Atlantic, Hudson Bay
Summer in the Gulf of Maine and north, they breed there and find food.
Come to LI late November – April, sometimes longer
Pups born mid-May – July, 75 cm, 10kg, swim from birth weaned in 3 – 4 weeks, mother’s milk 50% fat
Harp Seals – Pagophilus groenlandica - big spots and blotches, like dalmatians. Whiskers are cat-like, bushy and thinner. Can grow to 6 ft., 400lbs.
Other True Seals Hooded Seals – Cristophora cristata - blue backs, can grow up to 9 ft. and 900lbs., females 7 ft., 670lbs. Gray Seals – Halichoerus grypus - horse heads, long snout, molt in June. Can grow to 7.5-8 ft., 800lbs.
Types of Cetaceans
2 blow holes 1 blow hole
Baleen Whales - Mysticetes
Larger whales including:
Diet and Feeding
Filter feed by catching zooplankton or small schooling fish by skimming or gulping large volumes of prey in water.
Tongue forces water to back of mouth past hundreds of baleen plates acting as sieves to trap the prey, then swallow.
Humpback Whale – Megaptera novaeangliae
40-50 ft long, 40 tons
Males have complex whale song
Feed during summer in Arctic
Breaching, Tail flopping
Breed and give birth during winter
Population dropped by 90% during whaling industry
May live 50 years
Fin Whale – Balaenoptera physalus
70 ft long, 70 tons
Can swim up to 35 mph
Dives for as long as 50 minutes
Winters in the Arctic, food rich
Summers near Equator, live off fat
May live 90 years
Blue Whale – Balaenoptera musculus
75-90ft, 125tons – Earth’s largest animal ever
May consume 4 tons of zooplankton each day in summer
Summer most frequently off eastern Canada
Winter to Florida and Gulf of Mexico
May live 80 years
Toothed Whales - Odontocetes Smaller whales including: Beluga Orca Sperm Pilot Odontocetes Sperm Whale Pilot whale pod Orca Beluga
Diet and Feeding
Odontocetes have variable number of identical conical teeth or spade shaped teeth used to strain or grasp prey, primarily fish and squid
Sperm Whale – Physeter macroencephalus
60 ft, 70 tons
Square head 1/3 length of body
Narrow, underslung jaw
36-50 conical teeth in lower jaw only
Deepest, longest dives – up to 2 hours, 9,800 ft
Present year round in Gulf of Mexico and NC to Georges Bank
Killer Whale – Orcinus orca
30 ft, 8 tons
Round head, slight beak
20-26 teeth in both upper and lower rows
Diverse diet to include fish, squid, reptiles, marine mammals