Diversity of Animals

BIOL 1309

Animals are multicellular ____________.

eukaryotes

What makes an animal an animal?

1. ALL animals eat other organism to obtain nutrients

2. Animals are MOTILE- at least at one point during life cycle

3. ALL animals pass through common stages during embryo to adult development

4. Almost all animals have specialized tissues

Specialized tissues

many similar cells that act together to perform a specific function

What animal does NOT have specialized tissues?

sponges

Fossil evidence and genetic analyses indicate that the first animal evolved from what 570 million years ago?

flagellated protists

Cambrian explosion

dramatic increase in animal diversity about 540 million years ago

What ignited the Cambrian explosion?

• the evolution of hard body coverings led to complex predator-prey relationships

• atmospheric oxygen reached a high enough concentration to support mobile animals

• hox genes caused different body plans

ALL HYPOTHESES

Hox genes

genes that control the cells during development

Four types of tissues ONLY seen in animals

• Muscles

• Nerves

• Connective

• Epithelial

Muscles

allows an animal to move

Nerves

allows communication between body parts

Connective

allows transport of body fluids and structural support

Epithelial

covers the internal and external surfaces of organs and the external surface of the body

Most animals reproduce ____________.

sexually

Sexual reproduction involves fertilization of _______.

gametes

Asexual reproduction usually includes _________.

budding and fragmentation

Parthenogenesis

unfertilized eggs develop into new offspring, eggs are dipoloid, no sperm involved, chemical stimulate egg to divide.

Animals must have a form of ___________ in order to absorb nutrients from the food into their cells.

digestive system

Classification of animals are based on what?

• morphological characteristics

• developmental characteristics

• molecular comparisions

Animals are grouped together based on their shared characteristics

1. cell and tissue organization

2. body symmetry

3. germ layers

4. protostomes or deuterostomes

5. ecdysozoans or lophotrochozoans

6. body cavity

7. digestive tract

8. segmentation

Body symmetry

asymmetrical, radial, bilateral

radial symmetry

multiple body parts are arranged around a central axis

bilateral symmetry

only one plane can divide the animal into mirror images

asymmetrical symmetry

lack symmetry

Do sponges have organs or tissues?

NO

Blastula

sphere of cells surrounding a fluid-fluid cavity

Gastrulation

process that invlolves cell migration to create germ layers

Radial symmetry is how many germ layers?

two

Bilateral symmetry is how many germ layers?

three

Ectoderm

outer layer that will give rise to skin and the nervous system

Endoderm

inner layer that will become the digestive system

Mesoderm

between ecto and endoderm, gives rise to muscles, bones, circulatory system

Animals with _____ germ layers have a much greater variety in body forms and functions

three

In __________ the gut develops front to back, first opening is the mouth

protostomes

In ________ the gut develops back to front, first opening is the anus

deuterostomes

Protosomes are further divided into two groups

• ecdysozoans

  or

• lophotrochozoans

Ecdysozoans all ________.

molt

Lophotrochozoans all form ________ and share certain __________

larva, DNA sequences

Larva has two bands of ______ around the middle and a cluster of long _____ at the top

cilia, flagella

Acoelomates

do NOT have a true body cavity

Pseudocoelomates

body cavity incompletely lined by a mesoderm, only lines the body wall

“false” body cavity

Coelomates

have a true body cavity , organs are incased within the mesoderm

Animals have an ___________ digestive tract if the mouth takes in food and ejects waste

incomplete

Animals have a ___________ digestive tract if food passes in one direction from mouth to anus

complete

Segmentation

division of body parts or a series of repeating parts

Why is segmentation of the body plan important?

allows for free movement and development of certain body parts

Invertebrates are animals _______ a backbone

WITHOUT

Vertebrates are animals ______ a backbone

WITH