Page 23 - Science Course 2 (Book 1)

Chordates Mo1-L3a: What is a Chordate?
Lesson 3

Let’s Begin

In this topic, you will learn the following
lessons: Chordate

Mo.1-L3a: What is a Chordate? All chordates have four traits in common: a
Mo.1-L3b: What are the groups of Chordates? notochord, a tail, a nerve cord, and pharyngeal
pouches.

Hollow Dorsal
Nerve Cord
Mo1-L3a What is a Chordate? Post-anal tail Notochord

KEY CONCEPTS:
1. What characteristics do chordates have in
common?
2. What is the difference between vertebrate and Pharyngeal pouch
invertebrate chordates? • A notochord is a flexible rod-shaped structure that
supports the body of a developing chordate.
Vocabulary A-Z • Pharyngeal pouches are grooves along the side

Let us learn some vocabulary of a developing chordate.

Key Concept

Notochord What is a Chordate?
Name characteristics all chordates share.

Pharyngeal pouch

Notochord

a flexible, rod-shaped structure that supports the
body of a developing chordate.

Pharyngeal pouch

grooves along the side of a developing chordate.

Invertebrate Chordates Vertebrate Chordates

• Chordates that never develop backbones are called • Most of the animals you are familiar with—such as
invertebrate chordates. cats, dogs, fish, snakes, frogs, and birds—are
probably vertebrate chordates.
• The earliest chordates
probably looked similar to Backbone
lancelets—small animals Skull
found burrowed in the sand
just off ocean shores.
Hanged
Jaw
• Tunicates are a type of Vertebrate
invertebrate chordate that
looks like sponges but have • Most vertebrate chordates have jaws.
organized tissues and internal structures such as
organs. • As vertebrate bodies and skeletons continued to
adapt, vertebrates became better at catching food
and avoiding being eaten.
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