Duck
Otter
Echidna
Platypus
Begin
Duck
Otter
Echidna
Platypus
It took millions and millions of years for plants and animals to adapt, change and evolve into the variety of species that now exist on Planet Earth. Because of this, some animals may have more in common than you realize.
Your Mission:
You will be investigating three lines of evidence that scientists use to establish common ancestry among species.
Duck
Otter
Echidna
Platypus
First, let's take a closer look at four animals that seem to share some common traits.
Click on each animal to learn their key stats.
Consider:
Of the platypus, echidna, otter and duck, which two species do you think are most likely to be related?
Duck
Africa
Europe
Asia
Australia
North America
South America
Fun Fact: Ducks produce oil that makes their feathers waterproof.
Key Stats
Class
Bird
Weight
1-3.5 pounds
Habitat
Fresh water and salt water
Defense
Flight
Give birth To
Eggs
Favorite food
Worms, plants and fish
Home
North America, South America, Asia, Europe, Africa and Australia
Otter
Africa
Europe
Asia
North America
South America
Fun Fact: Otters are curious and love to play.
Key Stats
Class
Mammal
Weight
11-90 pounds
Habitat
Fresh water and salt water
Defense
Quick escapes and thick fur
Give birth to
Live young
Favorite food
- In the sea: mussels, crabs, snails and more
- In the river: crayfish, crabs, frogs and more
Home
North America, South America, Asia, Europe and Africa
Echidna
Australia
Fun Fact: Their sticky tongues help them catch their prey.
Key Stats
Class
Mammal
Weight
5-22 pounds
Habitat
Caves and burrows
Defense
Prickly spines
Give birth to
Eggs
Favorite food
Ants and termites
Home
Australia and Tasmania
Platypus
Australia
Fun Fact: Platypus use their bill to sense electrical currents in water.
Key Stats
Class
Mammal
Weight
1.5-5 pounds
Habitat
Fresh water
Defense
Adult males have venomous spurs
Give birth to
Eggs
Favorite food
Bottom-dwelling invertebrates like
shrimp and worms
Home
Australia and Tasmania
Embryology
To really investigate which two species are most closely related, you'll need more information and access to a real science laboratory. Join us at the Zoo Lab as we work together with scientists to learn more about each of these animals.
Two different word parts make up the word Embryology. The suffix "ology" means "the study of." The root word "Embryo" describes an unborn animal or human at one of its earliest forms of development.

Embryos that show distinct similarities likely descended from a common ancestor.
Chicken
Human
Fish
For example, the embryos of chickens and humans have slits on their necks that look very similar to the gills of fish. While chickens and humans don't actually develop these gills, the presence of these slits in their embryos is just one piece of evidence that helps scientists determine whether all three animals share common ancestry.
Illustrations are meant for instructional purposes only and are not scientific drawings.
In the Embryology Room, you'll be able to compare and contrast platypus, echidna, otter and duck embryos at three different stages in search of distinct similarities.
Click on each of the animals to see what they looked like in their youngest form, and then try to order the embryos from youngest to oldest.
EMBRYOS
Continue
Duck
Drag each embryo and order them from youngest to oldest.
Submit
Good Job!
Try Again!
Nice Try! Here's the correct answer:
Youngest
Oldest
Echidna
Drag each embryo and order them from youngest to oldest.
Submit
Good Job!
Try Again!
Nice Try! Here's the correct answer:
Youngest
Oldest
Otter
Drag each embryo and order them from youngest to oldest.
Submit
Good Job!
Try Again!
Nice Try! Here's the correct answer:
Youngest
Oldest
Platypus
Drag each embryo and order them from youngest to oldest.
Submit
Good Job!
Try Again!
Nice Try! Here's the correct answer:
Youngest
Oldest
Now that the embryos are organized, they're ready to study for similarities.

Based upon characteristics found in each set of embryos, choose which two animals are most similar.

Then, click on your notebook to record your findings.
Duck
Echidna
Otter
Platypus
Illustrations are meant for instructional purposes only and are not scientific drawings.
You've recorded your findings. Click to
1
Tracing Life's Roots
Great work!
In the Embryology Room you learned about the common characteristics between four animals and investigated which two species are most closely related.
You are now ready to visit the Anatomy Room!
Continue
Copyright © 2019 Discovery Education, Inc. All rights reserved.
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