Kingdom AnimaliaThe study of animals

is called Zoology

The Animals have 6 major Characteristics

1. Animals are multicellular ………………..

Except for sponges, animal cells are arranged into tissues (a tissue is a group of cells alike in structure and function… such as muscle tissue or

brain tissue). Tissues are necessary to produce organs and organ systems.

2. Animals are heterotrophs

• Heterotrophs can only consume their foods….. they are not capable of

making their own foods.

3. Animals are diploid• The dominant generation in the life cycle is the

diploid generation. Their gametes are heterogametes (different sizes); eggs are larger than sperm. Gametes are produced by meiosis. A typical animal life cycle is

shown below.

2N

Human Life Cycle

n2n

4. Animals are motile

• Heterotrophy often requires motility (the ability to move) to capture prey. Animals have motility during at least some part of

their life cycle.

5. Animals have a period of embryonic development

• During embryonic development, cells become specialized and form two or three layers of tissues. Tissues are groups of similar cells.

• Cell Specialization allows cells to perform more efficiently than requiring individual cells to

perform many functions. Cell Specialization allows the Division of Labor. Division of Labor.

6. Animal cells lack cell walls

• Therefore a skeleton is necessary to support the tissues of large animals.

The Origin of AnimalsAquatic, Colonial (multicellular), Heterotrophic ProtistsAquatic, Colonial (multicellular), Heterotrophic Protists

Choanoflagellates

The key to the success (survival ) of the Animals is their

Diversity….their variations.The Diversity of the Animals originates from

the variations that occur in their:• 1. Tissue Complexity• 2. Body Symmetry• 3. Cephalization• 4. GastroVascular Cavities (GVC)• 5. Coeloms• 6. Segmentation, and whether they are…..• 7. Protostomes or Deuterostomes.

1. Tissue Complexity

• Most animals, collectively called the eumetozoans, have closely functioning

tissues. Some organisms are diploblastic, have only two cell layers… such as the hydra

and jellyfish. Some organisms are triploblastic and have three cell layers. The

three “germ layers”germ layers” are the ectoderm, mesoderm and endoderm. There is a group

of animals, the parazoans (sponges) that are not organized into true tissue and lack

organs.

The Embryonic “Germ” Layers

• The three layers of tissues that become established during early embryonic development are called germ layers. They give rise to the body tissues.

These three layers are called….. 1. ectoderm, 2. mesoderm, and

3. endoderm.

The Embryonic Germ Layers develop from the Blastula….. Gastrula

Hollow ball of cells stage following the blastula, consisting of a hollow, two-layered sac of ectoderm and

endoderm surrounding an

archenteron

(opening)

archenteron

Gastrula

The Embryonic Germ Layers• The ectoderm forms from the

outer layer of cells. It gives rise to the skin, hair, nails and

nervous system. • mesoderm forms between

the ectoderm and endoderm. It becomes the muscles,

connective tissues, skeleton, kidneys, circulatory and

reproductive organs.• The endoderm made of cells

that form the tube-like structure in the gastrula.

These cells will form the lining of the GVC and the major

organs of the digestive system.

2. Body SymmetryThere’s 3 basis shapes…1. asymmetry, 2. radial

and 3. Bilateral symmetry

Asymmetry

• Asymmetrical animals have no

pattern of symmetry. The simplest animals

(sponges) are asymmetrical.

Radial Symmetry

• The body parts of a radially symmetrical animal are arranged

around a central axis so that each part extends

from the center. Animals that exhibit

radial symmetry tend to be sessile (immobile).

Radial symmetry allows them to reach out in all

directions.

Bilateral Symmetry• Only one cut along the

longitudinal axis will produce identical halves of a

bilaterally symmetrical animal. Bilateral symmetry is

best for motile animals.• Body Plan Includes

• Anterior (head) and Posterior (tail) ends

• Dorsal and Ventral surfaces• “Right” and “Left” sides are

mirror images

Longitudinal A

xis

Sponges Sea Anemone Humans

3. CephalizationThe term “Cephalo” means “head”.

In animals with bilateral symmetry, there is a

greater increase in the nerve tissue

concentrated in the anterior end (the head) as animals increase in

complexity. For example, brains have

formed with accessory organs for seeing,

hearing, tasting, etc.

4. Gastrovascular Cavity (GVC)

GastroVascular Cavities (GVC) are areas

where food is digested. If they have only one opening, the processing is limited.

Two openings designate a digestive tract allowing food to

be digested more thoroughly.

Gastrovascularcavity

5. Body Cavities

• The body cavity is a space that separates the gut and internal organs

from the rest of the body.

• It isolates the internal organs from body-wall movements.

• It also bathes the internal organs in a liquid through which nutrients and

wastes can diffuse.

The Arrangement of the Ectoderm, Mesoderm, and Endoderm

An acoelomate is an animal which does not have a coelom. A coelom is a body cavity which is

completely lined with mesoderm.

Digestive cavity

Flatworms are Acoelomates

A pseudocoelomate animal has a body cavity (called a pseudocoelom) located between

endoderm and mesoderm.

pseudocoelom

Digestive cavity

Roundworms are Pseudocoelomates

The body cavity of a coelomate animal (called a coelom) is located

within the mesoderm.

The mesentery holds the gut in place.

Digestive cavity

Coelom

Mesoderm

Earthworms are Coelomates

6. Segmentation• Many animals have segmented body parts. In some cases the parts

repeat over and over again, as with

earthworms. In other animals, the segments are modified, such as

with insects… they essentially have 3

segments…. the head, thorax and abdomen.

An Earthworm segmentation

7. Body PlansProtostomes or Dueterostomes?

Embryonic Development

• During early development, the fertilized egg divides, or cleavages, to produce a solid ball of cells. Then, cell

migration results in a hollow ball called a blastula.

Embryonic Development Gastrulation – the development of the Germ Layers

• Some cells of the blastula migrate inward producing a gastrula. The opening is the blastopore. The internal

cavity is called the archenteron.

archenteron

Embryonic Development

• The Gastrula will become the gut (digestive tract) of the mature animal. In species that have a separate mouth and

anus, the tube will eventually extend through the length of the embryo and fuse with the opposite side. One opening will

become the mouth, the other will become the anus.

( Blastopore becomes the anus)( Blastopore becomes the mouth)

BlastoporeBlastopore

6 Major Trends in Evolution1.1. multicellularity multicellularity

2. development of tissues, first none (sponges), then 2 (cnidarians), 2. development of tissues, first none (sponges), then 2 (cnidarians), then 3then 3

3. development of symmetry, first none (sponges), then radial 3. development of symmetry, first none (sponges), then radial (cnidarians), then bilateral (cnidarians), then bilateral

4. development of a GVC(gut), first none (sponges), then sac-like 4. development of a GVC(gut), first none (sponges), then sac-like (cnidarians, flatworms), then complete (cnidarians, flatworms), then complete

5. development of a body cavity, first none (flatworms), then a 5. development of a body cavity, first none (flatworms), then a pseudocoelom (roundworms), then a coelom pseudocoelom (roundworms), then a coelom

6. development of segmentation; segmentation evolved in 6. development of segmentation; segmentation evolved in protostomes (annelids and arthropods) independently of that protostomes (annelids and arthropods) independently of that

which evolved in deuterostomeswhich evolved in deuterostomes. .

Evolution of SymmetryEvolution of Symmetry

• The evolutionary sequence

progressed from asymmetrical

animals to radial and then to bilaterally

symmetrical animals.

Summary of Evolutionary Trends

Symmetry

Asymmetry Radial Bilateral

Gut

No Gut Saclike Complete

Coelom

Acoelomate Pseudocoelomate Coelomate

Embryonic Germ LayersNone 2, (tissues, no organs) 3, (tissues and organs)

Evolutionary TrendsPhylum Tissue

ComplexityGerm

Layers

Body

Symmetry

Gut

OpeningsCoelom Embryonic

Development

Porifera parazoa - asymmetry 0 - -Cnidaria eumetazoa 2 Radial

symmetry

1 - -Platyhelminthes eumetazoa 3 Bilateral

Symmetry1 acoelomate -

Nematoda eumetazoa 3 Bilateral Symmetry

2 pseudo-

coelomate -Rotifera eumetazoa 3 Bilateral

Symmetry2 pseudo-

coelomate -Mollusca eumetazoa 3 Bilateral

Symmetry2 coelomate protostome

Annelida eumetazoa 3 Bilateral Symmetry

2 coelomate protostome

Arthropoda eumetazoa 3 Bilateral Symmetry

2 coelomate protostome

Echinodermata eumetazoa 3 Radial

Symmetry

2 coelomate deuterostome

Chordata eumetazoa 3 Bilateral Symmetry

2 coelomate deuterostome

(sponges)

(jellyfish, hydra)

(flatworms)

(roundworms)

(rotifers)

(clams, snails)

(earthworms)

(insects, spiders)

(starfish, sea urchins)

(common name)

Classification of the Kingdom AnimaliaProtozoans

Asymmetry Radial Symmetry Protostomes Deuterostomes* No Body Plan •Body Radiates from

a Central Point•Mouth forms at the

Blastopore•Anus forms at the

Blastopore

Evolutionary Trend

Simple Complex

An increase in “Cell Specialization” and “Division of Labor”

1. Phylum Porifera

(Sponges)2. Phylum Cnidaria

(Jellyfish, Sea Anemone)

Bilateral Symmetry

Body Plan Includes

Anterior and Posterior Ends

Dorsal and Ventral Surfaces

“Right” and “Left” sides are mirror images

Radial Symmetry Bilateral Symmetry

CoelomatesPseudocoelomates

CoelomatesCoelomates

Acoelomates

3. Phylum Platyhelminthes

(Flatworms)

4. Phylum Nematoda

(Roundworms)

8. Phylum Arthropoda

(Insects, Spiders)

7. Phylum Mollusca

(Snails, Clams)

6. Phylum Annelida

(Segmented Worms)

9. Phylum Echinodermata

(Starfish, Sea Urchins)

10. Phylum Chordata

*Class Ichthyes

*Class Amphibia

*Class Reptilia

*Class Aves

*Class Mammalia

Phyla 1-9 are Invertebrates “Animals without backbones”

Coelom: body cavity found between two layers of mesoderm.

5. Phylum Rotifera

(Rotifers)

Kingdom Animalia Survey

1. Phylum Porifera(Sponges)

Phylum Porifera(Sponges)

(exit for water)

(digest and distribute food)

(skeleton)

Choanaocyte

*** Sponges are Parazoans: they contain NO true tissues

*** Sponges are filter feeders

2. Phylum Cnidaria

Jellyfish, Corals, and other Stingers

General Characteristics

• Simple body plan-bag shaped organism• Radially symmetrical organization

• Consists of a mouth and a sac-like cavity• Lacks an anus

• The mouth is surrounded by a ring of tentacles• The cavity in the center of the gut, called the

gastrovascular cavity.

Two Body Forms

• Polyps

- attached to a surface

- ex: sea anemones

- mouth points up

• Medusae

- free floating

-ex: jellyfish

-mouth points down

The Tissue Layers

Inner tissue layer (endoderm): gastrodermisOuter tissue layer (ectoderm): epidermis

-contains cnidocysts, the stinging cellsMiddle layer (lacks a mesoderm): mesoglea (jelly-like substance)

3. Phylum Platyhelminthes(Flatworms)

• Platyhelminthes consists of three kinds of acoelomate flatworms.

• 1. Free-living Flatworms: such as planarians, which are carnivorous scavengers.

• 2. Flukes: are internal, or external, parasites that suck tissue fluids or blood.

• 3. Tapeworms: internal parasites that live in the intestinal tracts of vertebrates.

Planaria

Tapeworm Scolex (head) Young

Proglottids

Old

Proglottids

** tapeworms appear to be segmented, but they are not true “segmented” worms

4. Phylum Nematoda(Roundworms)

• Found in fresh water, marine, moist soil, tissues of plants, and tissues and body fluids of animals

• A complete digestive tract is present and nutrients are

transported through the body in the pseudocoelomic fluid.

• Free-living forms are important in decomposition • Animal parasitic forms can be hazardous to health.

(Trichinella spiralis in humans via undercooked infected pork)

Nematode

5. Phylum Rotifera(Rotifers)

• Rotifers are small, mainly freshwater

organisms, although some are marine and others are found in

damp soil.• Complete digestive

system is present.• Rotifer refers to the

crown of cilia that draws a vortex of water

into the mouth.

Rotifer

6. Phylum Mollusca(snails, bivalves (such as clams….have a shell which has two parts), octopuses and squids)

• In Squids, the shell is reduced and is

internal.• In octopuses, the

shell is entirely absent.

• Octopuses have a highly developed

nervous system with a large, complex

brain.

Snails

7. Phylum Annelid(Segmented Worms: includes leeches,

earthworms and polychaetes)

Earthworms ingest soil, extract nutrients in the digestive system and deposit undigested material (mixed with mucus from the digestive tract) as casts through the anus. Important to farmers as they till the soil and castings improve soil texture.

Phylum Annelid(Segmented Worms: includes leeches,

earthworms and polychaetes)

Fanworm

Polychaete Worm

8. Phylum Arthropoda(spiders, insects, crustaceans, and various related organisms)

• Arthropods have two kinds of life cycles…(1) complete metamorphosis, (2) incomplete

metamorphosis.

• Arthropods have: * jointed appendages, * a well-developed nervous system, *

specialized body segments, and * an exoskeleton made of chiton.

The specialized body segments are the: Head, Thorax and Abdomen

Incomplete Metamorphosis (immature forms are often called nymphs)

Nymphs resemble the adult in form except for being smaller and lacking fully developed wings and sexual organs.

Life Cycle: Egg nymph adult

Complete metamorphosisImmature forms are called larvae (larva, singular).

The pupal stage is a transition stage, when the larva is transformed to the adult. Pupa molts to the adult form.

Life Cycle: Egg --> larva --> pupa --> adult

9. Phylum Echinodermata(sea stars (starfish), sea urchins and sand dollars)

Echinoderms are Coelomates, Deuterostomes

Echinoderms have complete digestive systems

Although some adults exhibit radial symmetry,

Some features are bilateral, as are

the body shape of their larvae.

10. Phylum Chordata

• The Phylum Chordata consists of animals that exhibit the following

four features. In many cases, these features are temporary, appearing

only during embryonic development.

1. A Notochord

• A notochord provides support for

the body. It is a flexible cord located

on the dorsal surface. In most

cases, the notochord is

replaced by bone during development.

Notochord

2. A Dorsal Nerve Cord

• A dorsal nerve cord forms the basis of

the nervous system. In some chordates,

the nerve cord becomes the brain and spinal cord.

3. Pharyngeal Gill Slits• Pharyngeal Gill Slits provides channels

across the pharynx to the outside of the body. In some chordates, the slits become gills for oxygen exchange, or for filter feeding, while

in others, the slits disappear during embryonic development.

4. A Muscular Tail

• A muscular tail extends beyond the digestive system. In many chordates, such as humans, the tail is lost during

embryonic development.