Whales. Fossil Record Shows that some land animals began to make the transition to sea animals about 50 million years ago.

Whales

Fossil Record

• Shows that some land animals began to make the transition to sea animals about 50 million years ago.

Mammals

• Whales are mammals and all mammals share 3 characteristics:

– Hair

– Feed young with milk from mammary glands

– Have a 4-chambered heart

Whales and Dolphins

belong to the Order CetaceaThere are about 80

species

Whales versus Dolphins• Whales are largest and dolphins and

porpoises are the smallest.

Baleen Whales• Two blowholes

• Baleen plates – filter feeders

Plates grow to several feet in length

May be several hundred in one animal

• Flat on outer edge, bristles on inner edge trap small organisms

• Krill: food source for many baleen whales

• Includes the humpback, blue, finback, right, sei, and gray whales.

Baleen

Toothed Whales• One blowhole

• Have teeth to seize prey

• Include the Sperm, killer, pilot, beluga, dolphins and porpoises

• Killer whales: top carnivores

Baleen Whale vs. Toothed Whale Size

Whale Reproduction• Fertilization and development are internal

• Whales breed about every 3 years and the female whale, or “cow”, stays pregnant between 11 and 18 months.

• Whales are born tail first.

• Nurse for 6-10 months

• A blue whale calf drinks the equivalent of 400 glasses of milk per day and the milk is 50% fat in content.

Whale Birth

Adaptations and Behaviors

• Whales breathe through their blowholes which are connected to their lungs, not their stomachs (Dory and Marlin would never have been shot out the blowhole).

• Blowhole is on the dorsal side of their bodies, up on their head, so it surfaces first

• Baleen whales have 2 blowholes, toothed whales have 1 blowhole

Blowhole

Swimming• Whales swim by the up and down

movement of their hind flippers or tail flukes

• The dorsal fin helps keep them on course

• Pectoral fins are used for steering, braking and balance.

• The bones inside the fin are similar to the bone structure of the hands of land mammals and whales still have hip bones.

Whale Skeleton

Diving• Whale uses its pectoral fins to change from horizontal to vertical.

• The tail flukes then push the body down into the water head-first

Lunging – swim up to the surface and engulf food (bubble net)

Lobtailing• Waves tail in the air

then smashes it into the water.

• Not fully understood by scientists

• May be a sign of aggression or a way to announce its presence.

Spyhopping• Whale raises

head above the water’s surface to look around for a few seconds.

• May be a sign of curiosity

Breaching – leaps almost completely out of the water and crashes back down with a huge splash.

Whale Migration

• Whales spend the summers feeding in the waters off the Bering Sea and Arctic Ocean. These waters are nutrient rich and contain a lot of plankton.

• During the winter, whales migrate to warmer, shallow waters around Baja California (Gray Whale) or Mexico (Humpback) to breed and have their young.

Migration Map

Keeping Warm• Blubber keeps

whales warm (they are endothermic or warm blooded) in water.

Echolocation- form of sonar where the whale bounces sound off of objects to detect objects in the water

Stranding• Stranding is where a dolphin or whale swims

into shallow waters and becomes beached. • The whales die as their internal organs are

crushed by their own body weight.• It is puzzling because, for whatever reason,

their echolocation system is not working.• May be caused by PCBs and DDT or natural

toxins in the water.

Mass Stranding

Pilot Whales are the most commonly stranded whale. May have been caused by the use of sonar by navy ships.

Threats to Cetaceans• 1. Hunting – both regulated and

unregulated• 2. Pollution – PCBs and DDT may

interfere with echolocation causing strandings– Oil slicks also a big problem

• 3. Overfishing or killing of whales’ food source(s).

• 4. Noise – interfering with echolocation• 5. Unintentional tangling in nets used for

other purposes (dolphins in tuna nets)

Blue

Humpback

Right

Minke

Gray

Toothed Whales

Narwhal

Spyhopping

Sperm

Beluga

Humpbacks are identified by the markings and shape of their tails(Also an example of lobtailing)