Page 26 - Science Course 2 (Book 1)

Mo1-L3b:What are the Groups of Chordates?

Lizards and snakes, turtles, and alligators and The one trait that makes birds different from all other
crocodiles are the three most common groups of animals is their feathers.
reptiles.

Wings and feathers are birds’ major adaptation for
flight.

Unlike reptiles, birds are
endotherms, animals that
Most reptiles live on land, and all have lungs for generate their body heat from
breathing. the inside.

Scales on their skin prevent reptiles from drying out.
All mammals have hair and mammary glands,
Most reptiles lay shelled eggs that don’t dry out. special tissues that produce milk for young
mammals.

The hair of mammals is an adaptation that helps
Inside reptile eggs is amnion, a protective membrane keep them warm.
that surrounds the embryo.

Reptiles are ectotherms, animals that heat their
bodies from heat in their environments. There are three groups of mammals:
monotremes, marsupials, and placental mammals.
Warming, or basking, in sunlight is a behavioral
adaptation of ectotherms. Monotremes, which include the platypus and the
echidna, lay eggs.

40 Horse(endotherm) Marsupials, including the opossum, raise
Body Temperature(°C) 30 Placental mammals have a

their young in pouches.

20

the young are attached to as they
10 structure called a placenta that
grow inside the mother.
Turtle(ectotherm)
0 10 20 30 40
Outside Temperature(°C)

19