Classification - Whales
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Transcript of Classification - Whales
Module B3 Life on Earth
IB3.2 Follow the evidence
B3 Life on Earth
• Whales are mammals.
• All mammals share some features.
B3 Life on Earth
• Whales belong to a group of mammals called the
Cetacea.
• Cetacea have two features that other mammals
don’t have.
B3 Life on Earth
• Cetaceans are split into four groups.
• Click if you want to know more about baleen plates
and echo-location.
Cetacean group Baleen plates? Teeth? Echo-location?
Baleen
Sperm
Other toothed
Beaked
Yes
No
No
No
No
Teeth in lower jaw only
Many teeth
Few teeth
No
Yes
Yes
Yes
B3 Life on Earth
• Which of these ways of classifying whales is the
most sensible?
• Use the evidence in the last slide to help you.
B3 Life on Earth
• From the evidence so far, baleen whales are more
different.
• There are 11 species of baleen whale.
• They include blue whales and sperm whales.
• Click if you want to know more about baleen
whales.
B3 Life on Earth
Q5, Q6
• But in the 1990s new
evidence was found.
• Scientists looked at DNA
from 16 species of
cetaceans.
• The DNA showed that:
- Sperm whales were
more closely related
to baleen whales
than other groups.
- Beaked whales are
only distantly related
to any of the other
groups.
• Look back at the your
choice for classifying
whales. Which way of
classifying seems best
now? Do you need to
change your mind?
B3 Life on Earth
Discuss with a colleague
• What is this lesson about?
• Suggest a suitable lesson objective(s) and outcomes for this lesson.
B3 Life on Earth
• Changing your ideas doesn’t mean that you were
wrong the first time. You just didn’t have enough
information.
• It also doesn’t mean that the new ideas are
definitely right. Any conclusion is only as good as
the evidence behind it.
B3 Life on Earth
• You can get up to date information about whale
classification here.
• There’s more background information on whales
here.