Chapter 32 & 33
Kingdom Animilia
- Over 1.5 million species
- Estimated 73 million
- 35 Phylums
- Over half are insects
- More similarities within animal genomes than other kingdoms
Characteristics
- Multicellular
- Lack of cell wall
- Sexual reproduction
- mobile sperm
- larger non-motile egg
- Nervous Tissue
- Complexity
- Responsiveness
- Hox Genes
- Special clusters of genes associated with the planning of the body
Metazoans
- All animals
- Multicellular animals
- Paratoans
- Sponges
- Eumetazoans
- "true" multicellular animals
Classification/Systematics
- Old
- Morphology
- Embryotic Development
- Recent
- Molecular genetics
Body Plans
Morphological and Developmental Features
- Body Symmetry
- Number of tissue Layers
- Patterns of Embryonic development
Symmetry
- Eumetazoa
- Divided by symmetry
- Radiata
- Radial symmetry
- Often Circular or tubular
- Bilateria
- Bilateral symmetry
- Dorsal
- Back
- Ventral
- Front
- Anterior
- Posterior
- cephalization
- enlarged head
Tissues
- Metazoa
- all animals
- divided on weather or not they have specialized tissues
- Parazoa
- Porfera
- sponges
- may have distinct cell types
- Porfera
- Enmetazoa
- more than one type of tissue
- organs
- all other animals
Germ Layers
- Radial
- 2 layers
- Diploblastic
- endoderm
- extoderm
- Bilateral
- 3 layers
- Triploblastic
- endoderm
- extoderm
- mesoderm
Embryonic Development
- Protostome
- Blastopore becomes mouth
- cleavage is determinate
- fate of embryonic cells are determined early
- Deuterostome (second opening)
- Blastopore becomes anus
- cleavage is indeterminate
- each cell produced by early cleavage can develop into a complete embryo
Other Morphological Characteristics
Used in classification
- Presence or absence or coelom
- Body segmentation
Molecular data suggest these features are unreliable in terms of understanding evolutionary history
Body Cavity
Coelom
-
- a fluid-filled body cavity
- Coelomate or eucolemate
- true coelom
- coelom completely lined with mesoderm
- Pseudocoelom
- coelom only partially lined with mesoderm
- rotifers and roundworms
- Acoelomate
- lack of a body cavity and instead have mesenchyme
- flatworms
Functions of the Coelom
- Cushions internal organs
- Enables movements and growth of internal organs independent of the body wall
- Fluid acts as a simple circulatory system
Segmentation
- Body may be divided into regions called segments
- occurs in annelid worms, arthropods, and chordates
- allows specialization of body region
DO NOT worry about the number of species
Molecular views of Animal Diversity
- Scientist now use molecular techniques to classify animals
- Compare similarities in DNA, rRNA, and Animo Acids
- Closely related organisms have fewer differences than those more distantly related
- Advantages over morphological data in that genetic sequences are easier to quantify and compare
- Example: A,T,G, and C in DNA
Genes used in Molecular Systematics
- Studies often focus on ribosomal RNA (rRNA)
- Universal in all organisms
- changes slowly over time
- Hox genes also studied often
- Found in all animals
- duplications in these genes may have led to evolution of body form
- Phylogenies constructed using rRNA and Hox genes are similar and often agree with those based on morphology
Invertebrates
- "without backbone"
- +95% of all species
Phylum Porifera
- Sponges
- lack tissues (organs)
- multicellular
- pores
- filter H2O and food
- Invertebrates
Phylum Cnidaria
- Jelly fish, corals, anemones
- Diploblastic development
- Two tissue layers
- Mesoclea
- gelatinous covering
- Nerve net
- interconnected nerve cells
- no brain
- One opening with gastrovascular cavity
- Protostomes
- Invertebrates
- Radial symmetry
- Salt and fresh water
- Stingers
Phylum Cterophora
- Comb jellies
- Same characteristics as Cnidaria
- Strictly salt water
- No Stingers
Phylum Platyhelminthes
- Flatworms, tapeworms, flukes
- Triploblastic
- Organs and organ systems
- Enhanced nerve net
- 2 cerebral ganglia
- One opening with gastrovascular cavity
- Protostomes
- invertebrates
- bilateral symmetry
- Acoelomate
Phylum Rotifera
- rotifers
- pseucoelomate
- Triploblastic
- Two openings
- complete gut tract
- alimentary canal
- Protostomes
- Corona
- simple brain
- invertebrates
Phylum Mollusea
- Snails, slugs, oysters, octopus, squid, clams, muscles
- Triploblastic
- Eucoelomate
- Complete gut tract
- Protostomes
- Invertebrates
- Three part Body
- Foot
- Visceral mass
- Mantle
- Many have outer shells
Phylum Annelida
- Segmented ring worms
- Triploblastic
- Eucoelomate
- Complete gut tract
- Protostomes
- Enhanced nervous system
- Invertebrates
Phylum Nematoda
- Roundworms
- Triploblastic
- Pseudocoelomate
- Complete gut tract
- Protostomes
- Invertebrates
Phylum Anthropoda
- Insects, crustaceans, spiders, ticks
- Highest diversity of animals
- >1.5 million species
- Hardened Exoskelton
- Protostomes
- Invertebrates
- Eucoelomate
- Triploblastic
- Complete gut tract
- Enhanced nervous system
- Insects, in particular, have an enhanced brain
- segmented appendages
Phylum Echinodermata
- sea stars, urchins, seacucumbers, sand dollars
- Triploblastic
- Eucoelomate
- Complete gut tract
- Deuterostomes
- Simple nervous system
- Endoskeleton
- series of plates
Phylum Chordota
- Deuterstomes
- Complete gut tract
- Endoskeleton
- Few invertebrates
- Mostly vertebrates
- Eucloemates
- Triploblastic
Four Critical Innovations of Chordata Body Design
NotochordDorsal, hollow nerve cordPharyngeal gill pouchesPost-anal tail
These four features are exhibited at some point of life history/developmentOnly some Fishes exhibit all four
Notochord
Cartilagenous supporting rod along the dorsal axisReplaced by jointed "backbone"Vertebral column of hardened cartilage or bone
Dorsal, hollow nerve cord
Expanded at the anterior endBrian
Enclosed/supported/protected by the Notocord
Pharyngeal gill pouches
Gill slitspharynxback of mouth cavity
Post-anal Tail
Tail extends posterior of the anus