1. A whirl-wind tour through the most prominent phyla!
Animal Diversity
A whirl-wind tour through the most prominent phyla!

2. Traditional Animal Phylogentic Tree
Which animals have a body cavity?
What are the possible functions of a body cavity in animals?

3. Animal Phylogeny – Modern
Based on sequences in ribosomal RNA (molecular systematics)
Acoelomate flatworms lost their coelom
Coelom development happened early
Combine phyla with lophophore and trocophore larvae
Combine phyla
that molt (ecdysis)
Fig 32.8

4. Radiata X X X X X X cnidocytes, unique in the animal kingdom
extracellular digestion in a gastrovascular cavity allow food larger than individual cells.
Describe the function of a gastrovascular cavity.
Tissues allow for different cells to take different roles

5. Plylum Cnidaria “cnidarians”
detect and respond to stimuli from any direction
muscles and simple nerve net
tissue-grade level of organization
Fig 33.6
Fig. 33.5

6. Polyp vs. medusa 2 tissue layers: 2 body forms: Fig. 33.4
skin (epidermis)
gastrovascular cavity lining
2 body forms:
polyp
medusa
Which body form is involved in sexual reproduction, and why?
Fig 33.4

7. Phylum Platyhelminthes – “flat worms”
first phyum with organ-system level of organization, and bilateral symmetry with some cephalization
gastrovascular cavity; secrete mucus and move by means of cilia and wave-like muscle contractions
A thin body between dorsal and ventral surfaces
NO coelom (acoelomate)
Flatworms, trematodes, tapeworms

8. Phylum Nemertea - “ribbon worms”
Actually acoelomate, but some similarities to the protostomes
Complete digestive tract; closed circulatory system
What are the advantages of a complete digestive tract?
…of a closed circulatory system?
What does this predict about size?
Photo from:

9. Phylum Mollusca – “mollusks”
Over 150,000 spp; mostly marine
Complete digestive tract; most have an open circulatory system
Soft body protected in most by a hard internal or external shell made of calcium carbonate
What other organisms manufacture CaCO3?
Bivalves: clams, etc.
Gastropods: snails, slugs
Cephalopods: squid, etc.
…and why is this process important to the biosphere?
Polyplacophora: chitons

10. Mollusk anatomy Important consumers: Filter feeders Grazers Carnivores
3 Main body parts:
Foot
movement
Visceral mass
internal organs
Mantle
secretes shell; gas exchange
Most use a strap like rasping organ called a radula to scrape food; cephalopods have a beak
In many the mantle extends to produce a water-filled chamber, the mantle cavity, which houses the anus and gills (portions of the mantle that increase surface area for gas exchange, making it more efficient).

11. Phylum Annelida – “segmented worms”
~15,000 species in 3 classes; marine, freshwater and damp soil
Body & some organs segmented (division of labor with regional specializations)
Polychaetes, earthworms & leeches
How do these worms exchange gasses?
Fig 33.24bcd

12. Segmented worm anatomy
Front segments contain sense organs and a well-developed brain
Complete digestive system and closed circulatory system
Complex movement
Circular muscles
Longitudinal muscles
Segmental hydrostatic skeleton
Setae
Segmentation: having a body built from repeated units (segments) allows a more precise control of the development and function of individual segments or groups of segments.

13. Summary Important evolutionary trends in body plan:
Multicellularity: Porifera
True tissues: Cnidaria
Bilateral symmetry: Platyhelminthes
Coelom: Mollusca (reduced or absent in some)
Segmentation: Mollusca (some), Annelida
These trends helped animals adapt to different environments or exploit the same environment in a different manner

14. Exoskeletons
must molt to grow (ecdysis)
Grasshopper molting
Fig 32.8

15. Phylum Nematoda – “round worms”
> 90,000 spp, in aquatic habitats, wet soils, many as decomposers or parasites inside plants and animals
Tough, transparent cuticle (mostly collagen)
Cylindrical body; longitudinal muscle only; pseudocoelom
Complete digestive tract
Trichinella
Fig a, b
Muscle cells

16. Phylum Arthropoda – “arthropods”
Jointed appendages (“jointed feet”)
> 1 million spp, most of them insects (beetles)
Most diverse, widely distributed & abundant of all the animal phyla
Hard exoskeleton of chitin
Relatively impermeable to water
Strong: protection & muscle attachment (striated muscle)
Non-living
What “problems” does a tough, waterproof exoskeleton create?
Fig 33.32

17. Arthropod anatomy Extensive cephalization
Well developed sense organs: sight, “taste”
Segmentation
some fused and modified into specialized regions (great diversification of form and function)
Basic Body Plan:
head
thorax
abdomen
Fig 33.26
Lobster: crustacean

18. Class Insecta - Insects
Most successful phylum
Mostly terrestrial, but often requiring water for reproduction
Only invertebrates with adaptations for flight
Fig 33.33
For what purpose(s)?
Fig 33.32
Fig 33.34

19. Class Arachnida – spiders, mites, ticks, scorpions
Mostly terrestrial
Cephalothorax (fused region)
6 pairs of appendages
2 pairs for feeding
4 pairs of walking legs
Fig 33.30b

20. Scorpions & mites Scorpion in defensive posture cf Fig 33.29
Parasitic mites in honey bee air tube

21. Class Crustacea – crabs, shrimp, barnacles
mostly marine
specialized appendages
carnivores, detritivores, filter feeders
Lobster
Barnacles
How do these mostly aquatic organisms exchange O2 and CO2?
Shrimp

22. Deuterostomes
Protostomes
Fig 32.7

23. Phylum Echinodermata – echinoderms
~ 7,000 spp, all marine
“spiny skin”
radial symmetry in adults (larvae bilateral)*
Endoskeleton
plates and projecting elements
functions like an exoskeleton
Water vascular system
sea stars
Brittle stars
Sea cucumbers
*How does this relate to lifestyle in adults vs. larvae?
Sea urchins
crinoids
Fig 33.37

24. Water vascular system Unique Fluid-filled tubes Tube feet:
begin in the madreporite
end in tube feet
Tube feet:
locomotion
food gathering
gas exchange
Fig 33.38