Animal Body Plans

Animal Body Plans

Criteria for Evolutionary Development & Classification

Cellular organizationSymmetryCoelomDigestive systemSegmentationCephalization

Kingdom Animalia

Symmetry

UnorganizedRadialBilateral

Cellular organization

Tissues, organs, systems

Coelom

Body cavity or not

Digestive system

None, 1 or 2 openings, how

Kingdom Animalia coelomdigestive tube

Segmentation

Repetition of body parts

Cephalization

Development of a “head end”

Kingdom Animalia

1st dinosaur

end of dinosaurs

1st reptiles1st amphibians1st land plants1st fish

1st invertebrates

Millions of YearsGeologic Time Scale

Ediacaran Fauna: distinctive group of fossils dating from and existing only during Precambrian time

• The fauna arose about 600 mya.

• Named for Australia's Ediacara hills, where it was first discovered. Such fossils were later found to be widespread.

• These animals lived in shallow seas and had soft bodies that bear little resemblance to later life forms, and were about 1 m in length.

• May be an evolutionary dead end

Reconstruction of the sea floor during the Vendian times when the Ediacaran organisms thrived

Ediacaran Fauna(600-540 MYBP)

end of Precambrian era

Edicarian Fauna

Ancient Seas at the During the Cambrian Radiation (540 MYBP)

Burgess Shale

Ancient Seas at the During the Cambrian Radiation

(540 MYBP)

Drawings based on fossils collected from Burgess Shale in British Columbia, Canada

Burgess Shale Fauna(540 MYBP)

An explosion of body plans

HallucigenaFeeding tentacles

spines

Similar to a sea urchin

Pikaia- earliest known chordate

Burgess Shale Fauna(540 MYBP)

Burgess Shale Fauna(540-530 MYBP

Anomalocaris

OpabiniaWiwaxia

Living Invertebrates

Phylogentic Relationships of Animals

Ancestral Protist

segmentation

true tissue

radial symmetrybilateral symmetry

Deuterostomes:eucoelom

Protostome: schizocoelem

pseudocoelom

Porifera

Cnideria

Platyhelminthes

Nematoda

Mollusca

Annelida Echinodermata

ChordataArthropoda

no true tissues

acoelom

Early Embryonic

Development of an Animal

Major Stages of Animal Development

• gametogenesis• fertilization• cleavage• blastula• gastrulation• differentiation and morphogenesis

Hypothetical Scheme for the Origin of Multicellularity in Animals

Fig. 32-9a

Eight-cell stage Eight-cell stage

Spiral and determinate Radial and indeterminate

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderms,

chordates)

Cleavage

Protostome vs Deuterostome

Fig. 32-9b

Coelom

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderms,

chordates)

KeyEctodermMesodermEndoderm

MesodermMesodermCoelom

Archenteron

Blastopore BlastoporeSolid masses of mesodermsplit and form coelom.

Folds of archenteronform coelom.

Coelom formationProtostome vs Deuterostome

Fig. 32-9c

Anus

Protostome development(examples: molluscs,

annelids)

Deuterostome development(examples: echinoderms,

chordates)

Anus

Mouth

Mouth

Digestive tube

(c) Fate of the blastopore

KeyEctodermMesodermEndoderm

Mouth develops from blastopore. Anus develops from blastopore.

Fate of BlastoporeProtostome vs Deuterostome

What is a Phylum?

Some Examples of Animal Phyla• Phylum Cnidaria

– sea anemones, corals, jellyfish, man-of-wars & hydroids• Phylum Mollusca

– snails, slugs, chitons, clams, oysters, octopods & squids• Phylum Arthropoda

– spiders, scorpions, crabs, shrimp, insects & centipedes• Phylum Echinodermata

– sea stars, sea urchins, sea cucumbers & sea lilies• Phylum Chordata

– sea squirts, fish, amphibian, reptiles, birds & mammals

Phylum Chordata

Major Body Plan Characteristics of Animals

• Symmetry• Primary Germ Layers• Gut Organization• Body Cavity• Segmentation• Skeletal Systems• Circulatory Systems• Appendages• Coloniality

Symmetry• Asymmetry• Radial Symmetry• Bilateral Symmetry

Symmetry

Radial Symmetry Bilateral Symmetry

Radial SymmetryJellyfish

Phylum Cnidaria

Pentamerous Radial Symmetry

Sea StarsPhylum Echinodermata

Bilateral SymmetrySlug

Phylum Mollusca

Bilateral Symmetry

SquidPhylum Mollusca

Primary Germ Layers

• None• Diploblastic• Triploblast

gut

ectoderm endoderm

mesoderm

Fates of the Primary Germ Layers

• Ectoderm– hair, nails, epidermis, brain, nerves

• Mesoderm– notochord (in chordates), dermis, blood

vessels, heart, bones, cartilage, muscle• Endoderm

– internal lining of the gut and respiratory pathways, liver, pancreas

The Formation of

Primary Germ Layers

The Formation of

Primary Germ Layers

Diploblastic

gutEndoderm

Ectoderm

Diploblastic- two germ layersPhylum Cnidaria

Triploblastic

gutEndoderm

Ectoderm

Mesoderm

Body Cavities

• Acoelomate• Eucoelomate• Pseudocoelomate

Acoelomate

(c) Acoelomate

Body covering(from ectoderm)

Wall of digestive cavity(from endoderm)

Tissue-filled region(from mesoderm)

Pseudocoelomate

Pseudocoelom

Body covering(from ectoderm)

Muscle layer(frommesoderm)

Digestive tract(from endoderm)

Eucoelomate

CoelomBody covering(from ectoderm)

Digestive tract(from endoderm)

Tissue layerlining coelomand suspendinginternal organs (from mesoderm)

Advantages of aFluid-Filled Body

Cavity

• hydrostatic skeleton

• greater freedom for internal organs

• greater body size because of body fluid circulation

Gut Organization

• No Gut• Blind Sac Gut• Complete Gut

No GutSponges

Phylum Porifera

No GutSponges

Phylum Porifera

Blind Sac GutPhylum Cnidaria

Complete Gut

Segmentation

SegmentationCentipede

Phylum Arthropoda

SegmentationLobster

Phylum Arthropoda

Skeleton

Functions of the Skeleton

• supports basic body form

• protection of soft internal tissues and organs

• facilitates locomotion

Skeleton

• Hydrostatic Skeletons• Hard Skeletons

–Exoskeletons–Endoskeletons

Hydrostatic SkeletonSea Anemone

Phylum Cnidaria

Hydrostatic Skeleton:A non compressible fluid held under pressure in a closed body compartment.

Uses antagonistic muscles for movement.

The gastrovascular cavity of the jellyfish acts as hydrostatic skeleton against which contractile cells can work.

Hydrostatic Skeleton

EarthwormPhylum Annelida

ExoskeletonChiton

Phylum Mollusca

ExoskeletonStony Coral

Phylum Cnidaria

EndoskeletonsVertebrates

Phylum Chordata

Types of Appendages

Functions of Appendages

• locomotion

• feeding

• sensory

• protection

TentaclesSea Anemone

Phylum Cnidaria

Jointed AppendagesBee Appendages

Phylum Arthropoda

Circulatory Systems

Functions of Circulatory Systems

• transport of nutrients and metabolic wastes

• maintains water and solute balance

• defense against pathogens

Circulatory System

• None (simple diffusion)• Body Cavity Circulation• Closed Circulatory System• Open Circulatory System

No Circulatory SystemComb Jelly

Phylum Ctenophora

Circulation in a Moon JellyfishPhylum Cnidaria

Closed Versus Open Circulatory Systems

Nervous Systems

Functions of Nervous systems

• integration of animal behavior

• processing and interpretation of sensory information

• elicits external and internal responses

Types of Nervous Systems

Coloniality

ColonialityCoral

Phylum Cnidaria

ColonialitySea Fan

Phylum Cnidaria

Coloniality Man-of-War

Phylum Cnidaria

Polymorphism in the Portuguese Man- of-War