23.2 Animal Diversity

Bell Ringer:In at least 3-5 sentences interpret this quote:

"Ability is what you're capable of doing. Motivation determines what you do. Attitude determines how well you do it."-Lou HoltzAmerican football coach

23.2 Animal Diversity

Bell Ringer

• 1-What are the four characteristics that all animals share?

• 2-Animals are heterotrophs. How might this have contributed to such great animal diversity?

23.2 Animal Diversity

KEY CONCEPTMore than 95 percent of all animal species are invertebrates.

23.2 Animal Diversity

Each animal phylum has a unique body plan.

• Vertebrates have an internal segmented backbone and are in phylum Chordata.

• Vertebrates make up less than 5% of all known animal species.

23.2 Animal Diversity

• Invertebrates do not have a backbone.• Invertebrates encompass most animal groups. Each

group is defined by structural and functional characteristics.

23.2 Animal Diversity

• Differences in body plans result from differences in the expression of Hox genes.– Hox genes tell embryonic cells which body part to

become (where limbs go or location of gut).– Mutations in Hox genes led to the vast diversity of

animal species. These mutations can change the entire body plan.

head tail

headtail

fruit fly genes

human HOX-B genes

23.2 Animal Diversity

How are Hox genes related to the diversity of body plans?

23.2 Animal Diversity

Animals are grouped using a variety of criteria.

• Three criteria are used to categorize animals. – body plan symmetry– tissue layers – developmental patterns

gastrovascularcavity

mouthmesoglea

oral arms

tentacles

blood vessels

brain

heartsmuscle

segment nerve cord

mouth

digestive track

23.2 Animal Diversity

• There are two types of body plan symmetry.– bilateral symmetry: body divides equally along one plane

Animals with bilateral symmetry can be divided equally along only one plane, which splits an animalinto mirror-image sides.

23.2 Animal Diversity

– radial symmetry: body arranged in circle around a central axis

• There are two types of body plan symmetry.

Animals with radial symmetry have body parts arranged in a circle around a central axis.

23.2 Animal Diversity

• Bilateral animals have three distinct layers of tissue (this makes them triploblastic)

• radial animals have only two.– both animal types have

ectoderm and endoderm– bilateral animals have

mesoderm• Animals are divided into two

major groups, protostomes and deuterostomes.– Protostomes form mouth-

first, and anus second.– Deuterostomes first form the

anus and then the mouth.

Protostome Deuterostome

23.2 Animal Diversity

A comparison of structure and genetics reveals the evolutionary history of animals.

• Protostomes and deuterostomes are the two major radiations on the animal phylogenetic tree.

Porifera Cnidaria Platyhelminthes AnnelidaMollusca Nematoda Arthropoda

EchinodermataChordata

RADIALRADIAL

NO TISSUESNO TISSUES

PROTOSTOMES

DUETEROSTOMES

jelly

fish,

cor

al, a

nem

ones

spon

ges

flatw

orm

s

Seg

men

ted

wor

ms

clam

s, s

nails

,oc

topu

ses

roun

dwor

ms

crus

tace

ans,

inse

cts,

spi

ders

sea

star

s,

sea

urch

ins

lanc

elet

s,ve

rtebr

ates

23.2 Animal Diversity

Porifera Cnidaria Platyhelminthes Annelida

Mollusca Nematoda ArthropodaEchinodermata

Chordata

RADIALRADIAL

NO TISSUESNO TISSUES

PROTOSTOMES

DUETEROSTOMES

23.2 Animal Diversity

• The current organization of the animal kingdom shows some unexpected relationships.

• Technological advancementshelp to clarify evolutionaryrelationships.

Systematics is a field dedicated to the study of relationships between organisms because things are constantly changing due to new discoveries.

23.2 Animal Diversity

What evidence was used to reorganize the animal kingdom?