23 pages covering the zoology module. Going over the different systems on classification, types of phylogenetic trees, and almost every phylum in the animal kingdom. As well as the basic identifiable characteristics to separate each group (e.g. body symmetry, cavities, lifestyle). Goes into detail ...
lecture notes based on the BIOL111 Molecules of Life Module
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LEC142: Zoology (LEC142)
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Criteria of Organism Classification:
1. Homologous: common feature from same ancestor
2. Analogous: similar feature from different ancestor
1. Primitive: every individual in group has it
2. Derivative: not every individual in group has it
Systematics:
1. Phenetic System: groups organisms based on phenotypic similarities only
Homologous characteristics = analogous characteristics
Doesn’t reconstruct evolutionary history
2. Cladistic system: based on similarity of characteristics that reflect evolutionary relationships
Derived characteristics = more important > primitive characteristics
Only accepts monophyletic groups
3. Classic system: based on similarity of characteristics that reflect evolutionary relationships
All shared characteristics = primitive + derived
Accepts monophyletic + paraphyletic groups
Types of Phylogenetic Trees:
1. Cladogram: node position indicates relative time but branch lengths are arbitrary
• Doesn’t indicate amount of time between ancestor + descendant
• Branches of equal length
2. Phylogram: branch length represents amount of change
3. Dendrogram/Ultrametric: nodes associated with specific geological time
Groups in Phylogenetic Trees:
1. Monophyletic: ancestor + all descendants e.g. Mammalian class
2. Paraphyletic: ancestor + not all descendants e.g. Reptilia class
3. Polyphyletic: missing ancestor + some descendants e.g. algae
Blue-green ancestor = eubacteria
Green + blue ancestor = missing
Phylogenetic Tree Hypothesis:
Parsimonious: choose tree with fewest evolutionary steps
Body form changes at different rate to DNA/RNA
Morphological similarities different to genetic similarities
More molecular evolution = not expressed in body form
Estimating Evolutionary Timelines:
Radiometric dating: compares radioactive isotope + decay product concentration to estimate age
Stratigraphy: layering of deposited rocks
Molecular clocks: amount of genetic divergence separates related species e.g. mitochondria
Comparing ribosome structure = can separate larger groups
6 Kingdoms:
1. Eubacteria: unicellular, prokaryotic e.g. cyanobacteria
2. Archaea: unicellular, prokaryotic, no peptidoglycan in cell wall e.g. halophile bacteria
3. Protista: unicellular, eukaryotic e.g. Paramecium algae
4. Fungi: multicellular, heterotrophic, non-motile
Animalia Kingdom:
Choanoflagellates: evolutionary ancestor of all animals
• Cell differentiation -> 4 types = epithelial, nervous, muscle, skeletal
• Unique blastula stage of development
• Mostly sexual reproduction
55 Phyla, 34 phyla = invertebrates, vertebrates < 1 phyla
= Porifera, Cnidaria, Platyhelminthes, Mollusca, Annelida, Nematoda, Echinodermata, Arthropoda,
Chordata
Body Plans:
Body Symmetry:
1. Asymmetric = primitive e.g. Porifera
2. Radial = primitive e.g. Cnidaria
3. Bilateral = modern e.g. Anthropods
Body Cavities:
1. Acoelomates: no body cavity, organs surrounded by mesenchyma, mesoderm, ectoderm
2. Coelomates: cavity contains organs + is surrounded by mesoderm
3. Pseudocoelomates: internal cavity contains organs + organs not surrounded by mesoderm
Coelome Development:
1. Protostomes:
a. 8 cell stage
b. 2 cell layers = offset
c. Forms blastula
d. Blastospore: entrance to cavity
e. Coelome forms digestive tube
f. Mouth develops from blastospore = opening of embryonic gut
2. Deuterostomes:
a. 8 cell stage
b. 2 cell layers = aligned
c. Forms blastula
d. Outward bulges off developing digestive tract -> form coelom
e. Anus develops from blastospore
Life Styles:
Parasite: doesn’t kill host
Parasitoids: keeps host alive while feeding but final stage = host death
Predator: kills host
, • Mostly asymmetric – some are radial
• No tissues + organs
• Made of flagellated collar cells
• Filter feeders: collar cells create water currents -> trap food particles in mucus
• Mostly hermaphrodites: 1 individual has female + male sex organs = release sperm + eggs ->
fertilisation in water = asexual reproduction
2. Cnidaria Phylum: Stinging = sea anemones, corals, jelly fish
• Aquatic + mostly marine
• Radial symmetry
• Acoelomates – have 1 opening for gastrovascular cavity
• 2 cell layers = epidermis + gastrodermis -> no mesoderm
• Mesoglea: extracellular matrix = hydrostatic skeleton + gelatine structure
• 2 body forms: sessile polyps + mobile medusae
• Stinging Cells: Sacs in tentacles contain thread -> discharges into prey + releases venom
Life Cycle:
a. Polyp colony asexually reproduce -> medusae bud
b. Medusae sexually reproduce by releasing sperm + eggs into water
c. External fertilisation -> planula larva -> mature polyp
Cnidaria Classes:
1) Hydrozoa: medusae, polyp, hydra
2) Scyphozoa: medusae = jellyfish
3) Cubozoa: medusae = jellyfish
4) Anthozoa: polyp = sea anemones, corals
Coral Reefs:
• Stony corals = cnidaria polyps
• Symbiotic zooxanthellae: unicellular photosynthetic protist
3. Platyhelminthes Phylum: flat worms, flukes + tape worms
• Free-living, aquatic + parasitic
• Bilateral symmetry
• Parasites = anaerobic, non-parasites = aerobic
• Acoelomates – 1 mouth + no anus
o Release waste through skin
• Parenchyma: soft tissue
Platyhelminthes Classes:
a. Turbellaria: free-living flatworm
b. Trematoda: endoparasite flukes of mammals
c. Cestoda: endoparasite tapeworms of mammals
d. Monogenea: ectoparasitic flatworms of fish
Pre-adaptations: small, asexual reproduction – for repair (grow 2 if cut in half), flat +
cylindrical, hermaphrodites in planarian worms, reduced sensory organs
Adaptations: loss of sensory organs as don’t need to hunt, attachment organs, anaerobic
respiration – low O2 inside organism
Life Cycle of Pork Tapeworm: Taenia solium
Matures in humans = primary host
Larve in pigs = secondary host
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