26.1 Intro to the Animal Kingdom Notes
 Nevada State Science Content Standard: L.12.D.1 Students know
organisms can be classified based on evolutionary relationships. E/S
 Objective:
List the characteristics that all animals share.
Describe the essential functions that animals carry out.
Identify the important trends in animal evolution.
 Key Vocabulary
Invertebrate – animal that does not have a backbone or vertebral column (p
657)
Vertebrate – animal that has a vertebral column, or backbone (p 657)
Feedback inhibition – process in which the product or result stops or limits the
process (p 658)
Blastula – hollow ball of cells formed when a zygote undergoes a series of
divisions (p 661)
Protosome – animal whose mouth is formed from its blastopore (p 661)
Deuterostome – animal whose anus is formed from the blastopore of a blastula
(p 661)
Endoderm – innermost germ layer of most animals; develops into the linings of
the digestive tract and much of the respiratory system (p 661)
Mesoderm – middle germ layer of most animals; giver rise to muscles and much
of the circulatory, reproductive, and excretory systems (p 661)
Ectoderm – outermost germ layer of most animals; giver rise to outer layer of
the skin, sense organs, and nerves (p 661)
Radial symmetry – body plan in which body parts repeat around the center of
the body; characteristic of sea anemones and sea stars (p 662)
Bilateral symmetry – body plan in which only a single, imaginary line can divide
the body into two equal halves; characteristic of worms, arthropods, and
chordates (p 662)
Cephalization – concentration of sense organs and nerve cells at the front of an
animals’ body (p 663)
What characteristics do all animals share? (p 657)
What essential functions do animals carry out? (p 658)
What are the important trends in animal evolution? (p 660)
How do radial symmetry and bilateral symmetry differ? (p 662)
How are body symmetry and cephalization related? (p 663)