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ZoologyUnit 1
TaxonomyProtozoa
Early Embryonic DevelopmentSimple Metazoans
Chapter 10 - Taxonomy 1. List the hierarchy of taxonomic ranks in
the modern classification system 2. Compare & contrast concepts of
species identification 3. Explain how taxonomic characters are
used to infer evolutionary relationships 4. Define “clade”. Use shared and
derived characters to construct cladograms 5. Identify characteristics that define the
Animal Kingdom
Taxonomic Ranks Taxonomic groupings are of human
design, and are organized in a way to simplify our thinking about living organisms
Early taxonomic systems recognized two Kingdoms, Plant and Animal
As more varied organisms have been discovered, many do not neatly fit into either the Plant or Animal Kingdom
Conflicts in Early Taxonomy
Fungi have cell walls and are sessile, but cannot make their own food
Many single celled organisms are capable of photosynthesis, but have well developed mechanisms for locomotion
Cyanobacteria (formerly known as Cyanophyta) are photosynthetic, but lack organelles and a true nucleus
Modern Taxonomy Taxonomic systems expanded from the
early 2 kingdom approach to the recognition of 5 kingdoms: Monera (the bacteria), Protista, Fungi, Plantae, and Animalia
Improvements in analytical techniques have uncovered significant differences in bacteria resulting in the recognition of 2 distinct types, Archaebacteria and Eubacteria
A new level at the top: Domain
Modern trends in taxonomy emphasize ancestral relationships over convenience. The addition of Domain above the Kingdom level allows grouping of related Kingdoms. There are 3 recognized Domains:• Archaea – Includes the Kingdom Archaebacteria• Eubacteria – The “true Bacteria”• Eukarya – Eukaryotes:
Includes Kingdom Protista, Fungi, Plantae and Animalia
Species There are different approaches to the
recognition of species. Each approach has advantages and disadvantages• Morphological Species Concept
Based on body form characteristics• Biological Species Concept
Based on the ability to interbreed• Evolutionary and Phylogenetic Species
Concepts Based on ancestral/evolutionary relationships
Biological Species Concept Based on the ability to interbreed Some closely related species can
interbreed, but their offspring are sterile (example: lion x tiger = liger)
http://www.youtube.com/watch?v=CD6vpheUoPE
Reflecting Ancestry in Taxonomy
Accurate interpretations of evolutionary relationships require a variety of evidence. The difficulty lies in determining which similarities are superficial and which reflect common ancestry• “Homology” reflects common ancestry• “Analogous” traits are evolved
independently in separate lineages
The Cladistic Approach Modern taxonomy is moving towards
greater emphasis on common ancestry Cladistics is based on identifying an
ancestral characteristic present in a lineage
Progressively smaller groupings are formed as the result of “derived” characteristics
A “clade” includes all descendants of a particular ancestral lineage
Sample Cladogram
Create a Cladogram Cladogram #1 moss conifer fern
Chloro-phyte
Angio-sperm
multicellular x x x o x
photosynthetic x x x x xproduces seeds o x o o x
vascular o x x o x
flowering o o o o x
Cladogram Sample #2
Cladogram #2 Bacteria Archaea Protozoa Animals Plants Algae Fungi
DNA x x x x x x x
Autotrophic some some o o x x o
Cell Wall x o o o x x x
Multicellular o o o x x o some
Peptidoglycan x o o o o o o
Nucleus o o x x x x x
Cladogram Sample #3
Cladogram #3Chondrichthyes
Urochordata
Amphibia Reptilia
Mammalia Aves
Osteichthyes
paired limbs o o x x x x o
feathers o o o o o x o
amniote egg o o o x x x o
mammary glands o o o o x o o
vertebrae x o x x x x x
notocord x x x x x x x
bony skeleton o o x x x x x
Kingdom Animalia Eukaryotic Multicellular Heterotrophic No cell wall No
Chloroplasts
Chapter 11 - Protozoa 6. Compare and contrast
protozoans with animals 7. Describe means of locomotion
employed by protozoans 8. Categorize major taxonomic
groups of protozoans
Protozoans = “first animals”
Animal-like protists. Unicellular, but:• Heterotrophic• Lack cell walls (usually)• Motile (usually)
http://www.youtube.com/watch?v=-zsdYOgTbOk&feature=related
Modes of Protozoan Locomotion
Cilia Relatively
short and densely distributed over the surface of the cell
Modes of Protozoan Locomotion
Flagellae Longer and
less numerous than cilia, but practically identical in internal structure
Structure of Cilia & Flagellae
Internal structure consists largely of bundles of microtubules in a “9+2” arrangement
9 pairs in a circular arrangement with 2 in the middle
Cilia and Flagellae http://www.youtube.com/watch?v=Q
GAm6hMysTA
Modes of Protozoan Locomotion
Pseudopodia Literally “false
feet” Extensions of
the cytoplasm used not only for movement but also for feeding
Feeding and Movement of Amoebae
http://www.youtube.com/watch?v=pvOz4V699gk
http://www.youtube.com/watch?v=KeQ1c6_Md1Q
http://www.youtube.com/watch?v=TOPMaNvGTvc
http://www.youtube.com/watch?v=d_Bkg8euB5Y
Modes of Protozoan Locomotion
Non-motile All of these
types are parasitic and rely on a “vector” for movement to a new host
Traditional Protozoan Taxonomy
Since motility is a trait generally associated with Animals, categorizing the protozoa by their locomotion was a logical approach:
Flagellates – use flagellae Ciliates – use cilia Sarcodines – use pseudopodia Sporozoans – are nonmotile
Chapter 12 – Simple Metazoans 9. Discuss the colonial flagellate hypothesis of
metazoan origin 10. Identify distinguishing characteristics of the
phylum mesozoa 11. Identify distinguishing characteristics of the
phylum placozoa 12. Identify distinguishing characteristics of the
phylum porifera 13. Discuss the fundamental anatomy of sponges 14. Relate variations in sponge canal systems to
feeding efficiency 15. Categorize the classes of sponges
Metazoans Metazoans, in contrast with
Protozoans, are truly multicellular (with some differentiation of tissues)
The most “primitive” of the metazoa are barely more than colonies of cells, but have some cells specialized for feeding, or reproduction, or locomotion
Protozoan Ancestor to Animalia 2 hypotheses have been advanced as to
the protozoan ancestor to the animals:• Amoeboid ancestor• Flagellate ancestor
Cells resembling each of these protozoan forms exist in some form within the Animal kingdom
The more accepted hypothesis is the Flagellate ancestor hypothesis
Flagellate Ancestor Hypothesis
Cells called “Choanocytes” in sponges are identical in form and behavior to Choanoflagellate protists, which may be free living or colonial
Multicellularity Multicellular organisms differ from
colonial organisms due to the specialization of cells and the division of labor that results.
Groups of cells that are structurally and functionally specialized are “tissues”
Tissues that combine together for related functions are “organs”
Organs that perform a broad coordinated function form a “system”
Differentiation & Development All animals share a common pattern of
embryonic development (suggesting a common ancestry)
Much of the phylogeny of Kingdom Animalia can be traced back to variations in early embryonic development
Animal phyla generally considered “primitive” only go through a few stages of development, while the more “complex” phyla go through additional stages
Early Embryonic Development
The zygote divides in two (“cleavage”), then 4, then 8, forming a raspberry shaped “morula”
Cleavage continues forming a hollow ball of cells called a “blastula”
Cleavage Patterns and Differentiation
Note that there are 2 different patterns of cleavage, Radial and Spiral
Spiral cleavage results in greater early differentiation of cells
Gastrulation The blastula caves
in on one end, forming an inner layer (endoderm) and an outer layer (ectoderm)
The resulting space (“Archenteron”) will form the digestive cavity
Phylum Mesozoa Mesozoa are basically an
elongated Morula – They never reach the Blastula stage
Mesozoans are at the “cellular level” of organization. No true tissues exist
The inner layer of cells are specialized for reproduction
All known forms are parasitic
Phylum Placozoa The body form of
placozoans is a flattened Blastula
Placozoa are also at the cellular level of organization
The “oral” surface is specialized for feeding and locomotion
Phylum Porifera – The Sponges
Phylum Porifera The name Porifera is
derived from many pores (ostia) that allow water to flow through the channels in the body wall, allowing the sponge to filter feed
The flow of water is driven by flagellated “choanocytes” lining the channels
Sponge Anatomy
Canal System Variations
SYCONOIDASCONOID LEUCONOID
Asconoid Sponges The simplest canal system Choanocytes line the spongeocoel
Syconoid Sponges The pouching
of the spongeocoel into radial canals increases the surface area of contact between choanocytes and water flow
Leuconoid Sponges
Incurrent canals direct water into specialized chambers lined with choanocytes
Excurrent canals direct water to the osculum to be expelled
Spongin and Spicules
Sponge Phylogeny Phylum Porifera is divided into 3 classes Class Calcarea
• Calcium carbonate spicules • All 3 canal system types represented
Class Hexactinellidae• 6 rayed, siliceous spicules• Syconoid or Leuconoid canal systems
Class Demospongiae• Siliceous spicules (not 6 rayed), spongin• Leuconoid canal systems