23.1 Animal Characteristics

EQ – Although diverse, what common characteristics do all

animal share?

Sea Slug

23.1 Animal Characteristics

Animals are the most physically diverse kingdom of

organisms and all are multicellular heterotrophs.

• Animals range in size from 25-meter-long blue whales

to microscopic rotifers.

• Animals are found nearly everywhere on Earth.

23.1 Animal Characteristics

All animals share a set of characteristics.

• All animals share a unique set of derived

characters.

• Animal cells are

supported by collagen.

– three-stranded

protein

– found in bone,

skin, ligaments,

fingernails,

and hair

23.1 Animal Characteristics

– diploid parents produce diploid offspring

• Animals are diploid and usually reproduce sexually.

Diploid cells have two copies of each chromosome:

one copy from the mother and one from the father

– do not have free-living haploid life stages

23.1 Animal Characteristics

– Homeotic genes control early development.

– Hox genes determine the position of cells differentiation.

– A Hox gene mutation leads to the development of a body structure in the wrong position.

• Most animals have Hox genes.

23.2 Animal Diversity

KEY CONCEPT - More than 95 percent of all animal species

are invertebrates.

Sea Slugs eat Sponges

23.2 Animal Diversity

Animals are grouped using a variety of criteria.

• Three criteria are used to categorize animals.

1. Body plan symmetry

- Bilateral

- Radial

2. Tissue layers

3. Developmental patterns

gastrovascular

cavity

mouth

mesoglea

oral arms

tentacles

blood vessels

brain

hearts

muscle

segmentnerve 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 animal

into 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.

– bilateral symmetry: body divides equally along one plane

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; radial

animals have only two.

– both animal types have

ectoderm and endoderm

– bilateral animals have

mesoderm

• Animals are divided into two

major groups, the protostomes

and the deuterostomes.

– Protostomes form mouth-

first, and anus second.

– Deuterostomes first form the

anus and then the mouth.

23.2 Animal Diversity

A comparison of structure and genetics reveals the

evolutionary history of animals.Porifera Cnidaria Platyhelminthes

Annelida

Mollusca Nematoda ArthropodaEchinodermata

Chordata

RADIAL

1. NO TISSUES

5. PROTOSTOMES – first opening of digestive

cavity forms the mouth

6. DEUTEROSTOMES –

First opening

Of digestive cavity

Forms into anus

jellyfish, cora

l, a

nem

ones

sponges

fla

two

rms

Segm

ente

d

wo

rms

cla

ms, snails,

octo

puses

roundw

orm

s

cru

sta

cea

ns,

insects

, spid

ers

sea s

tars

,

sea u

rchin

s

lancele

ts,

vert

ebra

tes

2. TISSUES – groups of cells work together

3. RADIAL– body parts arranged in

a circle around a central axis4. BILATERAL– body divided equally

by one plane

23.2 Animal DiversityGeneral Characteristics of K. Animalia

1. Animals are multicellular.

2. The cells of animals are eukaryotic and the cells lack cell

walls.

3. Animals must obtain food from their environment.

(Heterotrophic) Animals are not capable of photosynthesis.

4. Most animals are motile because of a nervous system and a

muscular system. Three examples of animals that are sessile

(stationary) feeders are sponges, mussels and barnacles.

5. Most animals reproduce sexually.

6. The two major groups within the animal kingdom are

invertebrates and vertebrates.

7. In this kingdom the young usually have the same basic

features as the adults.

8. Organisms in Kingdom Animalia usually display a defined

shape or symmetry.

9. There are 30 different phyla in Kingdom Animalia.

23.2 Animal Diversity

Body symmetry:

23.2 Animal Diversity

Symmetry & Dissection Planes: