Select the one animal that has all of the placental mammal traits listed above.
Japanese tree frog tadpoles hatch from eggs without shells. The tadpoles live underwater. After some time, they grow legs and crawl onto land. Adult Japanese tree frogs have moist, smooth green skin. Orangutans live mostly in trees and have long, reddish hair. Orangutans give birth to live offspring.
Placental mammals are a group of animals with similar traits. The following traits can be used to identify placental mammals:
They give birth to live offspring.
They have fur or hair. Observe the animals and read the descriptions.
Scientists sort animals with similar traits into groups. This is called classification. Classification helps scientists learn about how animals live.
How do scientists classify animals? First, they make observations about an animal. Scientists observe the animal's traits, including its body parts and behavior. Then, scientists compare the animal's traits to other animals' traits. Scientists classify animals with similar traits into a group.
To decide if an animal is part of a group, look at the traits of the group.
Placental mammals have the following traits:
They give birth to live offspring.
They have fur or hair.
Compare each animal's traits to the group's traits. Select the animal with traits similar to the group's traits.
A Japanese tree frog has the following traits:
It spends part of its life in water and part on land.
It has moist skin.
It makes eggs with no shells.
A Japanese tree frog does not have all of the traits of a placental mammal. A Japanese tree frog is an amphibian.
An orangutan has the following traits:
It gives birth to live offspring.
An orangutan has the traits of a placental mammal. An orangutan is a placental mammal.