1. Invertebrate animals Multicellular animals that lack backbones
Approach is cumbersome

2. Phylogeny of the invertebrates
Early forms were ____-bodied, _____, ~ _ bya
Had no skeleton or shell
Most billion-year-old rocks have been re-formed
Few fossils >500 m.y.a. ______
Scientists also study ‘_____ fossils’ & speculate
Living species that have ancient traits
Invertebrate diversity flourished ~____ m.y.a.
________ Period of the ________ Era

3. Burgess Shales, Rocky Mtns., British Columbia
~550 m.y.a.

4. The major branches of life
Kingdoms:
Fungi
(external
digestion)
Plantae
(photosynthetic)
Animalia
(ingest food)
Protist Kingdoms
Multicellular
Unicellular
Domains:
Archaea
Eukaryota
Bacteria
Prokaryotic
cell design
Eukaryotic
1st cellular organism

5. Early development of invertebrates vs. vertebrates
Early cell division – _____ - in all animal zygotes:
blastula
Fertilized
egg
2-cell
4-cell
32-cell
_______: fluid filled sphere of identical cells
Undifferentiated “____” cells

6. Gastrulation: formation of the ____
Among invertebrates:
1st indentation in blastula becomes the ______
Anus
blastula
gastrula
Mouth
(1st invagination)
1st “invagination”
= _________ (“1st mouth”) development
Vertebrates are deuterostomes, “2nd mouth”
2nd invagination becomes _______

7. Phylogenetic trends in invertebrate body design
1. Increasing variety of tissue types
Sponges lack ____ tissues
Jellies lack _____ tissue
2. Increasing variety of organ systems
Sponges and jellies ____:
Circulatory organs (e.g., heart)
Respiratory organs (gills/lungs)
Skeletal system
3. Increasingly _______ body symmetry
Asymmetrical -> Radial -> bilateral

8. 4. Increased cephalization, development of a “____”
Only bilateral animals have heads (forward moving)
Where _______ receptors are concentrated
Improves predatory ability
Simplest example in _________:

9. 5. Increasingly complex ____ segmentation
No segmentation: e.g., flatworms
Simple external segmentation: e.g., earthworms
Repeated segments, like a cut loaf of bread
Early arthropods had legs on _____ segment
Segment __________: e.g., spiders
Fusing of head, thorax, and abdomen segments

10. 6. Increasingly complex gut
___ gut: individual cells digest food, e.g. sponges
Sac-like _______ gut: single opening
E.g., jellies, flatworms
Complete (___________) gut: mouth & anus
Earthworms, mollusks, arthropods, vertebrates

11. External segmentation
Phylogenetic tree of multicellular animals reflects
increasing body complexity:
Roundworms
Segmented
worms
Arthropods
Flatworms
Jellies
Exoskeleton
Unsegmented
Sponges
Radial
symmetry
External segmentation
Asymmetry
Bilateral
symmetry
Internal segmentation
Endoskeleton
Ancestral multicellular animal
Vertebrates

12. A survey of the major invertebrate phyla:
The Sponges: Phylum Porifera
________ multicellular animals
Resemble ________ of single-celled organisms
Specialized cells can live _____________
__ tissues, organs, or organ systems

13. Typical sponge: “skin” cells (________) amoebocyte cells (________)
spicule (non-living)
(_________)
flagellated cell
(_________)
pore cell
(_________)

14. Jellies & Anemones:
Phylum Cnidaria
Have fleshy _______ and _______ cells
___ skeleton
Keep shape with water pressure
Some tissues:
Simple muscles
Jellies: contractile ____ cells (no muscle)
Anemones: true muscle _______
Nerve net: like fish-net ______
____ brain or spinal cord
Some organ systems:
___-like digestive system
No ____

15. Flatworms: Phylum Platyhelminthes
planarians
tapeworms
flukes
________ body
Simple bilateralism and __________
Simple reproductive and excretory systems
Usually hermaphroditic – both sexes

16. Roundworms: Phylum Nematoda
Super-abundant in muck and _____
Have a _______ digestive tract
Many are endoparasites
E.g., Hookworm
Human roundworm
Filarial worm
Elephantiasis

17. Segmented worms: Phylum Annelida
Earthworms & leeches
Many organ systems
Circulatory system
Moves ______ through body
Excretory system
Filters out ____________
Recovers useful ___________
Nervous system
Nerve _____ serve as ‘switching points’
Allows __________ of body segments

18. Mollusks: Phylum Mollusca
Snails, clams, octopuses
Variety of life-forms
All have a ___________
____-like in snails
______-like in clams
_____-like in octopus

19. General features of mollusks:
All have _______________ body design
Most have soft body and hard _____
Open or closed circulatory systems
Open in ‘____’ species (snails, clams)
Organs “float” in ____ of blood: blood _______
Closed in _______ predators (squid, octopus)
Blood contained within ______
High blood _________ possible
Simple respiratory systems:
_____ in aquatic forms
Simple ____ in terrestrial forms

20. Arthropods (“jointed legs”): Phylum Arthropoda
Insects, spiders, and crustaceans
Invaded land after _____, before ___________
~ ____ m.y.a.
Exoskeleton
Must _____ to grow
Body segmentation
Probably evolved from ______
Segments fused into ________
Head: sensory organs, mouth
Thorax: legs and/or wings
Abdomen: respiratory & sex organs

21. Appendages: modified extensions of the body
Modified according to life-styles of species
Sensory reception, feeding, walking, hopping, flight
Differences used in _________ classification
Insects
Crabs & lobsters
Arachnids
_ pr antennae
_ pr. legs
___ pr. wings
_ pr. antennae
_ pr. legs
many abdominal
appendages
__ antennae
_ pr. walking legs
_ pr. “feeling legs”
(________)