Animal Diversity (3)

Chapter 32

Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers.

What are the key characteristics of animals?

Animals are heterotrophs that ingest their food.

How do animals obtain their food?

collagen supports animal cells instead of a cell wall.

What structural proteins supports animal cells instead of a cell wall?

Nervous tissue and muscle tissue

What tissues are unique to animals?

groups of similar cells that act as a functional unit.

What are tissues in animals?

sexually, with the diploid stage usually dominating the life cycle.

How do most animals reproduce?

The zygote undergoes cleavage

What is the process of rapid cell division that occurs after fertilization?

formation of a multicellular, hollow blastula.

What does cleavage lead to in animal development?

process where the blastula forms a gastrula with different layers of embryonic tissues.

What is gastrulation?

at least one

How many larval stages do most animals have?

sexually immature and morphologically distinct stage that eventually undergoes metamorphosis to become a juvenile.

What is a larva?

metamorphosis

What does larva undergo through to become a juvenile?

A juvenile resembles an adult but is not yet sexually mature.

How is a juvenile different from an adult?

body plan, a set of morphological and developmental traits.

How do zoologists categorize animals?

symmetry or asymmetry of their bodies

How can animals be categorized?

Radial and bilateral

What are the two major types of animal symmetry?

A flowerpot

What is an example of radial symmetry?

They have a top and a bottom but no front, back, left, or right sides.

How are radially symmetrical animals structured?

A shovel

What is an example of bilateral symmetry?

They have a dorsal (top) side, a ventral (bottom) side, a right and left side, and anterior (front) and posterior (back) ends.

How are bilaterally symmetrical animals structured?

Many bilateral animals actively move, so their sensory equipment, such as a brain, is concentrated in the anterior end for navigation.

Why do bilateral animals often have sensory equipment at their anterior end?

Radial animals are often sessile or planktonic (drifting or weakly swimming), while bilateral animals typically move actively and have a central nervous system.

How do radial and bilateral animals differ in movement?

sessile (nonmoving) or planktonic

How do radial animals move?

actively and have a central nervous system

How do bilateral animals move?

During development, three germ layers give rise to the tissues and organs of the animal embryo.

How do tissues develop in animals?

the germ layer covering the embryo’s surface.

What is the ectoderm?

the innermost germ layer and lines the developing digestive tube, called the archenteron.

What is the endoderm?

archenteron

what is the digestive tube called in the endoderm layer?

animals have only ectoderm and endoderm.

What are diploblastic animals?

animals have an additional intermediate tissue layer called mesoderm. (also having endoderm and ectoderm)

What are triploblastic animals?

bilateral symmetry

What type of symmetry do all triploblastic animals have?

body cavity

What do most triploblastic animals possess?

a true body cavity derived from mesoderm.

What is a coelom?

animals that possess a true coelom.

What are coelomates?

a body cavity derived from the mesoderm and endoderm.

What is a pseudocoelom?

Triploblastic animals that possess a pseudocoelom (fake body cavity)

What are pseudocoelomates?

Triploblastic animals that lack a body cavity

What are acoelomates?

cushions suspended organs

acts as a skeleton for muscle function

allows internal organs to grow and move independently of the outer body wall.

What are the functions of a body cavity?

protostome development or deuterostome development.

How are animals categorized based on early development?

forms during gastrulation and connects the archenteron to the exterior of the gastrula.

What is the blastopore?

mouth

What does the blastopore become in protostome development?

anus

What does the blastopore become in deuterostome development?