Invertebrate Zoology Animals without Backbones.

Invertebrate Zoology

Animals without Backbones

Patterns of the Invertebrate

• Symmetry- orientation around a central axis

• Germ Layers- embryonic tissue

• Deuterosome vs Protostome

• Body openings and digestion

• Coelom development

Deuterostomes

• Indeterminate cleavage

• blastophore becomes anus/second opening becomes mouth

• radial cleavage-cells of cleavage are aligned

Protostomes

• Determinate cleavage in most ( fate fixed early)

• blastophore develops into a mouth first

• Spiral cleavage-cells do NOT line up

Symmetry• ( a ) radial- can be

divided along any plane, through a central axis into roughly equal halves

• ( b ) bilateral- can be divided down it’s length only one way into similar right and left halves

• (not shown asymmetry-irregular in shape

Germ Layers

1. Ectoderm- outermost germ layer (forms skin, nerves )

2. Mesoderm- middle germ layer ( forms muscle, kidney, liver etc.)

3. Endoderm- innermost germ layer ( forms digestive and reproductive tract )

1.

2

3

Mesoderm forms as an outpocketing from endoderm

ectoderm

endoderm

Coelom

• Coelomate- has a true coelom CAVITY WITHIN A BODY

• Acoelomate- lacks a true coelom

• Pseudocoelomate- false body cavity ( no mesodermal connection )

Body Cavity

• COELOM- true cavity within a body

• Acoelomate- lacks a true body cavity

• Pseudocoelomate- has a false body cavity ( cavity develops with no mesodemal connection )

• Coelomate- true body cavity developing from out pockets of the mesoderm

SUMMARYGERM LAYERS

1. Ectoderm- outermost germ layer (forms skin, nerves )

2. Mesoderm- middle germ layer ( forms muscle, kidney, liver etc.)

3. Endoderm- innermost germ layer ( forms digestive and reproductive tract )

BODY SYMMETRY

• Symmetry- orientation around a central axis• ( a ) radial- can be divided along any plane,

through a central axis into roughly equal halves

• ( b ) bilateral- can be divided down it’s length only one way into similar right and left halves

• (not shown asymmetry-irregular in shape

Invertebrate Phyla

Porifera

Parazoa-lacking true tissue

Filter feeders- incurrent and excurrent pore ( osculachoanocytes- collar cells that create currentamoebocytes- capture food by phagocytosis

Spicules- silica or calcium carbonate skeletal structuresSpongin- protein in some species for support

Hermaphrodites contain both male and female sex organsBEHAVE LIKE A COLONY

Cnidarians

Eumetazoan- have true tissuesRadial symmetryacoelomate- lack a coelomdiploblastic- only two germ layersAlternation of generationpolyp- plant likemedusa- free swimming ( jelly fish like

Digestive traffic-two way, gastrovascular cavity-no separate

circulatory/digestive system

Nematocyst- stinging cell

Sea Anemone

Phylum Cnidaria

Class HydrozoahydraClass Scyphozoajelly fishClass Anthozoasea anemone

BUD-----

nematocyst

Platyhelminthes

Planaria

Nematoda

• Three germ layers

• Pseudocoelomate

• One-way digestive pattern

• Little need for resp. or digestive system

• Separate sexes

• Parasitic and free-living

ectoderm

endoderm

mesoderm

Rotifera• Mostly freshwater

• Pseudocoelom with several organ systems

• Crown of cilia around mouth

• Both sexual and asexual reproduction

S- SYMMETRY assymetryGL-GERM LAYERS noneBO-BODY OPENINGS manyBC-BODY CAVITIES acoelomateDT-DIGESTIVE TRAFFICnone, filter feeds cells digestCS-CIRCULATORY SYSTEMnone, filter water to remove water

phylum sym germ layeropen cav diges circporifera asy nonemany acoel none nonecnidaria rad 2 1 acoel two gastrovascular cavityplaty bil 3 1 acoel twonematoda bil 3 2 pseudo one noneannelida bil 3 2 coelom one closed with 5 heartsmollusca bil 3 2 coelom one bivalves-open, ceph-closedechinodermatarad 3 1 coelom water vascular systemarthropoda bil 3 2 coelom one open system

digestive traffic is direction of digestive system

characteristic inse

cta

arac

hnid

a

chio

poda

dipl

opod

a

crus

tace

a

segments A.orB.A C C Aappendages H, K. DOP K,G F E jointedlocomotion Z, K. D G F Efeeding N N,O N N Nnervous sys K.,L. K.,L. K.,L. K.,L.K.,L. sensoryrespiration V V V V X gas exchangereproduction Y Y Y Y Yexcretion R R R R Q. eliminate nitrogen waste

circulation S S S S S