Gray
Whale Enemy Number One
Photo
Mike Hawe
Hear
live recordings of killer whales off British Columbia. >>
Orcas (Killer
whales) are one of the dangers on the whales'
journey north. Sightings of Orcas increase
during the migration season. Here's
what Marine Biologist Caitlyn Toropova told Journey North about the connection
between gray whales and Killer whales:
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What
do you think happened to this whale's tail? (enlarge) |
Orcas
As Hunters
"Although killer whales can and do eat gray whales occasionally, there
is a lot more to it than that. Killer whales are the gray whales' main predator. Killer whales are amazingly good and adaptable hunters. That means they
can eat many different kinds of food using many different techniques. (Not
many animals can do that!)
"When killer
whales do attack a gray whale, several things happen:
- The victim
is almost always a calf. This means the orcas usually have to separate
the calf from its mother. Doing this takes coordination, skill, and
communication among many killer whales. (This can take up to 6 hours.)
- After
the calf is separated, the killer whales attack in very deliberate
ways. They
often teach the youngest of the killer whale pack how to make the kill.
Usually, just the victim's tongue and lower jaw are eaten. This is
a
bit of a mystery, considering there is a lot more meat on the whale
and the kill took extraordinary amounts of energy.
- When
attacks on gray whales do happen, the entire process is rarely seen
from start
to finish. Killer whales are like wolves in that a pack works together
with strategy to make a kill."
Transients
and Residents: Different Killer Whale Pods
Photo
Mike Hawe |
Photo Lindescom |
Resident
Orcas feed on fish—but NOT usually on marine mammals. Transient
Orcas feed on marine mammals. How can you tell them apart? Look at
the top of the DORSAL fin. If it
is rounded, the orca is a resident. If it is pointed, the
orca is a transient.
How would you identify the Orcas in these
photos?
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Try
This! Journaling
Questions
- Imagine
you are a gray whale mother taking your calf on its first migration.
Describe your hopes and your fears for the long journey north. (Also
see Literature Link: Whale
Journey)
- Think
of a "journey" that you have made in your life. It can
be a trip OR a series of events in order to meet a goal. What were
the dangers
or
scary parts?
How did you face and overcome them?
National
Science Education Standards
- Organisms
have basic needs.
-
All animals
depend on plants. Some animals eat plants for food. Others eat animals
that eat plants
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