1. Introduction to Animal Evolution

2. What is an animal? Major Themes --> How would you know?
What are the challenges that all animals must deal with?
Are there some fundamental similarities in the ways that animals solve these problems (similar adaptations) ?
Major Themes -->

3. Growth & Development form and function are related
Compare the means of support for animal and plant bodies.
differentiation and specialization into tissues
tissues, organs, and organ systems
body plan, size, and symmetry
How is it possible that cells of the same animal can have a different structure and function?
reproduction
sexual and asexual
developmental stages
What is significant about the fact that larval forms are “sexually immature”?

4. Sensing and Responding to the Environment
sensory systems
Describe what is meant by “environment” in this context. Provide some examples of conditions that are monitored.
motor systems (locomotion)
What special tissue(s) enable this kind of movement?
feeding and digestive functions
Describe some examples of how body structure is related to feeding style.

5. Internal Regulation energy balance transport
What factors may influence an animal’s “energy budget”?
transport
water
nutrients and wastes
gas exchange
How do animals cope with abiotic stresses?
intercellular communication
local
long distance
Provide one example of each type of intercellular communication.

6. Proposed evolution of the animals
Molecular studies indicate that animals, not plants, are the closest relatives of fungi.
Both Animals and Fungi are related most closely to a group of Protists known as the choanoflagellates (collar flagellates)
Kingdom began in ocean during Precambrian (Late Proterozoic era)
More than 100,000 species of fungi are known and mycologists estimate that there are actually about 1.5 million species worldwide.
Proposed evolution of the animals
Fig 28.8

7. Early embryonic development can help organize the diversity of animal life
What type of cell division occurs during cleavage?
When does the body form take on a “tube within a tube” appearance?

8. Patterns in Animal Evolution
Simple to more complex body form
Hypothesized colonial flagellated protist ancestor
Cell aggregates, to a gastrula-like (or tissue-grade) “protoanimal” to
Fig. 32.3
Which stages demonstrate cell differentiation? … morphogenesis?

9. The Parazoa - Phylum Porifera
“pore-bearers”
The Parazoa - Phylum Porifera
Describe at least two functions of amoebocytes.
How would you describe the feeding strategy?
No gastrulation occurs during development; no true tissues
If sponges have no muscle or nerve tissues, how do they accomplish movement of water into the spongocoel?

10. Patterns in Animal Evolution (continued)
tissues organized into organs and organ systems (a “tube w/in a tube” body plan, with 3 embryonic germ layers)
Discuss the concept of “stem cells” in the context of animal embryology.
Mesoderm (although, not in all animals)
Fig. 32.1
Characteristics of the body plan (anatomy) and embryonic development are key to understanding the relationships between different animal groups.

11. Patterns in Animal Evolution (continued)
Bodies with no symmetry to bodies with symmetry
Branch Radiata
2 germ layers: ectoderm & endoderm
Branch Bilateria
3 germ layers
Which body form demonstrates cephalization?
Describe at least one example of an animal with a high degree of cephalization. What other characteristics are associated with cephalization?
Fig. 32.5

12. Patterns in Animal Evolution (continued)
What do the colored layers represent?
Fig. 32.6
Bodies with no body cavity (e.g. flatworms)
to bodies with a “false” body cavity
(e.g. rotifers and round worms)
to bodies with a “true” body cavity
pseudocoelom
coelom
What normally fills the pseudocoelom?

13. Coelomates Differences include: Cleavage Fate of blastopore
Fig. 32.7
Coelomates
Differences include:
Cleavage
Fate of blastopore
Process of coelom formation
Name one organism representative of the animal groups listed at the top of the figure.

14. How is structure related to function at major stages in the life cycle of a sea star?
What can early embryonic development tell us about phylogentic relationships in animals?
What is metamorphosis, and how is it different from morphogenesis?

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

16. 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

17. X X X X X X
Tissues allow for different cells to take different roles: cnidocytes, unique in the animal kingdom, and extracellular digestion by gastrodermis allow food larger than individual cells.

18. Plylum Cnidaria “cnidarians”
extracellular digestion by gastrodermis allows food larger than individual cells
Radial symmetry - detect and respond to stimuli from any direction
Muscles and simple nerve net
Fig 33.6

19. Polyp vs. medusa 2 cell layers Skin Gastro-vascular cavity lining
2 body forms
polyp
medusa
Hydra eating
Swimming jelly fish
Fig 33.4

20. Phylum Platyhelminthes – “flat worms”
Bilateral symmetry with some cephalization; gastrovascular cavity
A thin body between dorsal and ventral surfaces
NO coelom (acoelomate)
Flatworms, trematodes, tapeworms
Fig 33.12

21. 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?
Photo from:

22. Phylum mollusca – “mollusks”
Over 150,000 spp; mostly marine
Soft body protected in most by a hard shell made of calcium carbonate
Bivalves: clams, etc.
Gastropods: snails, slugs
Fig 33.20
Fig 33.18
Polyplacophora: chitons
Cephalopods: squid, etc.
Fig 33.17
Fig 33.22b

23. Mollusk anatomy Important consumers: Filter feeders Grazers Carnivores
3 Main body parts:
Foot
movement
Viscera 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).