WHALES

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WHALES

• aquatic mammals

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Whales and dolphins are cetaceansfrom the Greek
word ketos or whale

• They originated as land mammals, but evolved from
  the land to the sea about 50-60 million years
  ago.
• The bones in a whales pectoral fin are very
  similar to the bones in a human arm showing their
  common ancestry.

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Whales of Australasia

• There are 35 species of cetacean in New Zealand
  waters
• 8 are baleen whales
• 27 are toothed whales
• New Zealand has 3 species not occurring in
  Australia
• Australia has another 10 species which are not
  found in New Zealand.

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Toothed Whales Baleen Whales

• Whales are divided into 2 groups according to the
  way they obtain their food.
• Toothed whales have teeth. This group of
  cetaceans are called Odontoceti.
• Baleen whales do not have teeth but instead have
  a mesh of bristles called baleen that is attached
  to the upper jaw and acts as a filter. Baleen,
  like human hair, is made of keratin. This group
  of cetaceans are called Mysticeti.

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BALEEN WHALES

• Baleen means with moustaches.
• They have evolved to eat huge quantities of small
  organisms called plankton which are available in
  some areas e.g. krill in Antarctic waters.
• They generally live longer than toothed whales,
  up to 70 80 years has been known.
• They have two blowholes.

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Baleen Whales
The humpback whale above represents a typical
baleen whale.
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How they feed -

• Some of them gulp in the water including the food
  and squeeze the water out the side of their
  mouth. These whales are rorquals and have pleats
  under their throats which expand to allow them to
  gulp huge quantities of water. A Blue Whale can
  gulp up to 5 tons of water.
• Others such as the Right Whale swim with their
  mouths open and swing their head from side to
  side using the baleen to filter out the plankton.
• Now try the investigation to show how baleen
  filters food.

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TOOTHED WHALES

• They have one blowhole.
• Most female toothed whales are smaller than males
  while in baleen whales females are generally
  larger than the males.
• In the next diagram, a bottlenose dolphin is used
  to represent toothed whales.

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Toothed Whales
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How they feed -

• Toothed whales eat fish and squid by grasping
  them in their teeth.
• They do not chew their food, but use their tongue
  to turn the fish so that it goes down head first.
• The Killer Whale is the only true eater of
  warm-blooded prey. They have been known to eat
  seals and other cetaceans.
• Watch the video of Orca hunting.

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Whales are not fish! They are mammals

• They are warm-blooded give birth to live babies
  (tail first) and feed them with milk rich in
  nutrients.
• The gestation period varies according to the
  species but may be between 9 to 18 months.
• Baby whales dont suck, instead the milk is
  squirted out of the teats down the babys throat.
• Whale tail flukes are horizontal structures
  their tails move up and down, instead of side to
  side as fish tails do.

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Mammal breathing . not fish breathing

• Whales must surface in order to breathe, unlike
  fish. This can be spotted by an observer by the
  blow or spout from the whales blowhole.
  Click here to watch a sperm whale blowing.
• Blowholes are like nostrils on top of their heads
  and the blow is actually condensing water
  vapour.
• Whales are able to stay under water because their
  lungs fill to their capacity and they change up
  to 90 of this each time they breathe.

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How do whales keep warm?

• They store some of their food as an insulating
  layer of blubber just under the skins surface.
• The blubber reduces heat loss to the surrounding
  water and also acts as an energy reserve for long
  migrations.
• Now try the experiment to demonstrate how blubber
  is effective in reducing heat loss.

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Sleeping and Swimming

• Whales have very streamlined bodies to help them
  move easily through the water.
• Cetaceans are among the fastest swimmers in the
  sea. They are powered by their tail flukes moving
  up and down.
• Their flippers are for balance and steering.
• Whales sleep with their blowhole just at the
  water surface. They control their breathing even
  when asleep.
• If they lose consciousness the blowhole closes to
  avoid drowning.
• Whales tend to take short naps.

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Being Social

• Cetaceans generally live in groups called pods
  which vary greatly in size according to the
  species.
• Some group into nursery groups at breeding times
  with the males remaining apart at other times.
• Another whale is often involved during the birth
  of a calf and helps nudge the calf to the surface
  to take its first breaths.
• It may be that some social behaviour is
  responsible for whales not leaving other stranded
  whales after they themselves have been rescued.

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Sensing

• The sense of sight is not the predominant one for
  whales given the murkiness of their environment.
• The sense of touch is present demonstrated by
  whales rubbing against each other.
• Toothed whales do not have a sense of smell, and
  it is limited in baleen whales.
• Toothed whales use echolocation to sense things
  around them. Baleen whales may use it but less is
  known about this.

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Echolocation

• The whales make a clicking sound which produces
  vibrations that travel through the water.
• The sound waves are bounced off any solid
  objects, and the whale is able to work out the
  direction and distance of the object, and even
  its shape, e.g. whether it is another animal or
  the sea floor.
• Watch the video of echolocation helping to hunt a
  giant squid.

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Communicating

• Toothed whales communicate by making whistling
  sounds which appear to transmit complex and
  intentional messages.
• Baleen whales produce a variety of sounds
  including whistles, clicks, thumps and moans.
• Humpbacks are known for their singing some
  songs can last up to 30 minutes and are thought
  to be the longest and most complex of any animal.
  These are really love songs and occur during
  the breeding season.
• A Blue Whales whistle is the loudest sound known
  to be produced by anything living.
• Watch the video about research that was carried
  out on how and what whales hear.

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Migration

• Many whales migrate between feeding and breeding
  grounds, e.g.
• Humpbacks migrate north to around Samoa, Tonga
  and New Caledonia to breed in autumn and south to
  the Antarctic to feed in spring.
• The whales migrate in 3 phases
• The pregnant females leave first in order to get
  to the new feeding grounds first and so get the
  most food.
• The males migrate next.
• Finally, the non-pregnant females and those with
  calves.

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Tracking the effects of humans on whales

• Marine scientists have been tracking the
  migratory patterns of whales in order to study
  how whales are affected by changes in the
  environment.
• For example, scientists have found that toxic
  pollutants in the water suppress whales immune
  systems, causing many to grow sick and die.