biol 1030 [1] - animal diversity 09 w notes. · pdf file• two large, general groups of...
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Biology 1030 Winter 2009
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Animal DiversityChapters 32, 33 and 34 (select pages)
• Three Domains of life– Bacteria
– Archaea
– Eukarya• True nucleus
True organelles
Living Organisms
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• True organelles
• Heterotrophic– Animals
– Fungi
– Protists
• Autotrophic– Plants
– Protists
Heterotrophic Protists• Paraphyletic grouping
– Lack chloroplasts
• Protozoans– Unicellular
• Animal like protists
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• Animal-like protists– Diplomonads (Giardia)
– Ciliates (Paramecium)
– Unikonta
• Amoebozoans
– (Amoeba)
• Opisthokonta
– (Choanoflagelates)
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Choanoflagelates
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• Predecessor of all animals
• Colonial protists
• Collared cells
What is an Animal?• Animals are characterized by multiple traits:
– Multicellular
• Cells interconnected through various junctions
– Lack cell walls
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Lack cell walls
– Heterotrophic
– Directional motion
– Diplontic life cycle
– Tissues develop fromgerm layers
Animal Diversity• Over 1.5 million
described species of animals– Insects– Underestimate
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• Two large, general groups of animals:
1. Invertebrates
2. Vertebrates
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Phyla• A large taxonomic grouping of related
animals
• 30-35 total phyla
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• 10 ‘major’ phyla
Phyla You Need to Know• Porifera
• Cnidaria
• Echinodermata
• Chordata
• Nematoda
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• Nematoda
• Arthropoda
• Platyhelminthes
• Brachiopoda
• Annelida
• Mollusca
Animal Classification• To classify animals, we ask the following questions:
1. Are there true tissues?
2. If yes, how many layers?
3. What is the pattern of development?
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4. How do they grow?
4b. Special structure?
5. Is there body symmetry?
6. Is there a body cavity?
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1. Are Tissues Present?• What is a tissue?
– A group of cells
– If one or a few cells are removed:• They cannot perform their task
• They will eventually die
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• Two major groups– Parazoa
• Phylum Porifera
– Eumetazoa• Everything else
Ph. Porifera• The Sponges
• The first animals
– Colonial protists (Choanoflagellates)
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• All are aquatic and benthic
Poriferan Body Plan• Sponges have no true
tissues– Three layers of cells only
• Pinacoderm– Pinacocytes
P t
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– Porocytes• Mesohyl
– ‘Spongocytes’ • Choanoderm
– Choanocytes
• But…– Why not true tissues?– Totipotency
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Poriferan Body Plan• Each cell is totipotent
– Not dependent on each other
– Able to change
– Useful for asexual reproduction
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2. How Many Tissue Layers?
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• Animals with true tissues
• Invagination of a hollow ball of cells
– Ectoderm outside
– Endoderm inside
= Diploblastic
How Many Tissue Layers?• In most animals
– Ectoderm
– Endoderm
– Mesoderm forms between
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• Two major groups:
– Diploblastic
– Triploblastic
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Phylum Cnidaria• Jelly fish, anemones,
corals
• Diploblastic– Ectoderm (epidermis)
– Endoderm (gastrodermis)
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Endoderm (gastrodermis)
– Space between is filled with mesoglea
• 2 basic body shapes– Medusa
– Polyp
Cnidocytes
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• Nematocysts
• Specialized stinging cell– Highly venomous
– Paralyzes prey
Cnidarian Body Plan• Colonial cnidarians
– All individuals are clones
• Corals– Autozooids are similar in
morphology
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p gy
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Cnidarian Body Plan• Specialized colony
members– Dactylozooid– Gastrozooid– Gonozooid
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3. What Type of Development?• Animal development
• Diplontic life cycle
• The zygote
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• The zygote– Undergoes cleavage
• The morula– A solid ball of cells
• The blastula– A hollow ball of cells
Gastrulation• Arranges the tissue layers correctly
• Forms the primitive digestive tract or archenteron
• Creates an opening (blastopore)
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3. What Type of Development?• Fates of the blastopore:
1. Formation of the mouth
• Protostome development (mouth first)
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2. Formation of the anus
• Mouth forms later
• Deuterostomedevelopment (mouth second)
The Deuterostomes• Radial cleavage
• Indeterminate development
• Enterocoelous
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– Outpockets from archenteron
• Echinodermata
• Chordata
The Protostomes• Spiral cleavage
• Determinate development
• Schizocoelous
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– Splitting of solid masses of mesoderm
• The remaining phyla
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Phylum Echinodermata• Divided into 5 major classes
– Class Crinoidea
– Class Asteroidea
– Class Ophiroidea
– Class Echinoidea
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– Class Holothuroidea
• All species are marine
Echinoderm Body Plan• Larvae have bilateral
symmetry
• Pentaradial (secondary) symmetry as adults
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Echinoderm Body Plan• The water vascular system
– Locomotion– Gas exchange– Circulation– Prey capture
• An adaptation of their coeloms!
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• An adaptation of their coeloms!
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Echinoderm Body Plan• All have a calcareous endoskeleton of several
plates or ossicles
– Microscopic remnants
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Echinoderm Regeneration
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Phylum Chordata• Characteristics
– Dorsal hollow nerve cord
– Notochord
– Post-anal tail
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– Pharayngeal gill arches/slits
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Phylum Chordata• Three major subphyla
– Subphylum Cephalochordata
– Subphylum Urochordata
– Subphylum Vertebrata
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Pharyngeal Gill Arches• Highly modified in the
more derived chordates– Ancestral uses
– Form the jaws (arch 1)
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j ( )
– Form the inner ear(arches 1 & 2)
– Form the cartilages of the throat (arches 4 & 5)
Subphylum Cephalochordata• The lancelets
• Small, fish-like animals
• Only 25 species
• Filter-feeders, catching food in their 100+ gill
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arches
• Believed to be the earliest chordates
– Fossils found in the Burgess Shale and Chengjiang deposits
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Subphylum Urochordata • The tunicates
• Defining characteristics only in the larval stages of development
• Most are filter-feeders, but one is an active predator
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active predator
Subphylum Vertebrata
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Recall the Protostomes• Spiral cleavage
• Determinate development
• Schizocoelous
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– Splitting of solid masses of mesoderm
• The remaining phyla
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4. What Type of Growth Pattern?• Two different methods of growth
– Growth by continually extending their skeletons
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– Growth by moulting body coverings
The Lophotrochozoans• Growth by extension of
their skeletons
• A common larval form– Trochophore larva
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– Annelids & Mollusks
• A feeding structure– Lophophore
– Brachiopods
• Neither– Platyhelminths
The Ecdysozoans• These animals are covered
by a hard covering
• Growth occurs by moultingor shedding their cuticle or
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exoskeleton– Ecdysis
• Nematodes& Arthropods
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Phylum Nematoda• The round worms
• The most abundant group of the Eumetazoa– Found in all habitats
– Free-living and parasitic forms
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Nematode Body Plan• Free-living species are
generally small, interstitial worms – µm – mm scale
• Parasitic species can be
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Parasitic species can be very large– cm – m scale!
• Dracunculus can grow over 1m!
Nematode Body Plan• Body covering is a cuticle
– A clear, tough but flexible, non-living covering
– Not an exoskeleton
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Free-Living Nematodes
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Parasitic Nematodes
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Phylum Arthropoda• Well over 1,000,000 species described!
• All arthropods are characterized by:
• Exoskeleton with jointed appendages
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• Segmentation is obvious– Generally each segment has a pair of appendages
Arthropod Body Plan
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– Similar segments are grouped into body regaions or tagmata
Phylum Arthropoda• Divided into multiple Subphyla including:
– Subphylum Myriapoda
– Subphylum Cheliceriformes
– Subphylum Hexapoda
– Subphylum Crustacea
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p y
• Centipedes and millipedes
• Homonomoussegmentation– Except for the head region
Myriapod Body Plan
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Except for the head region
• Legs are simple unbranched– The major difference is the number of legs per
segment
~30 segments × 2 legs/segment =
~190 segments × 4 legs/segment =
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Cheliceriform Body Plan• The spiders, mites, scorpions and ticks
• Segments are grouped into 2 tagmata
– Anterior cephalothorax
– Posterior abdomen
• The chelicerae (chelicera sing.)
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• 4 pairs of unbranchedwalking legs
• No antennae
• Over 1,000,000 described species!– Dominate terrestrial environments
• Light-weight chitinous exoskeleton
• Three tagmata
– Head – 5 segments
Hexapod Body Plan
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– Thorax – 3 segments
• Legs and wings
– Abdomen – up to 11
Crustacean Body Plan• The crabs, lobsters, shrimp, barnacles, copepods
– Mostly aquatic with a few terrestrial species
• Heavy calcarious carapace
• Body divided into 2 tagmata
– Cephalothorax
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• Biramous appendages
• Several pairs of antennae
– Abdomen – or tail
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The Lophotrochozoans• Growth by extension of
their skeletons
• A common larval form– Trochophore larva
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– Annelids & Mollusks
• A feeding structure– Lophophore
– Brachiopods
• Neither– Platyhelminths
Phylum Platyhelminthes• The flat worms
• Possess neither a trochophore larvae or a lophophore
• 3 major classesClass Turbellaria
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– Class Turbellaria
– Class Cestoda
– Class Trematoda
• They have a solid body construction
– Acoelomate
• All flat worms exhibit bilateral symmetry
R di t li ht iti t
Platyhelminth Body Plan
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– Rudimentary light-sensitive eye-spots
• Flat worms have an incomplete, two-way gut
– The gastrovascular cavity
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Phylum Platyhelminthes
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Phylum Brachiopoda• The lamp shells
• One of a few lophophorate phyla
• Not clams!– Different plane of symmetry
– Different mode of life
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Different mode of life
– Different musculature
Brachiopod Body Plan• Most are sessile - pedicle
– Some dig through the sand
• Valves are produced by a mantle as in the molluscs
P d i t i th f il
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– Predominant in the fossil record
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Protostome Development?• Cleavage is radial
• The second opening becomes the mouth– The blastopore disappears
• The third opening becomes the anus (if it forms)– The Inarticulata have a complete, 1-way gut
– The Articulata have an incomplete, 2-way gut
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e t cu ata a e a co p ete, ay gut
Phylum Annelida• The segmented worms
• Three major classes
– Class Polychaeta
– Class Oligocaeta
– Class Hirudinea
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Annelid Body Plan• Obvious segmentation
– In many, the segments are all similar –homonomous
– Others have segments that are specialized –heteronomous
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Annelid Body Plan• Trochophore larval
• Paired setae (chaetae) on nearly all segments– Polychaetae –
– Oigochaetae –
– Hirudinea –
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Polychaete Body Plan• Predominantly marine worms with
parapodia on each segment– Multitasking
• Well-developed head with palps– Multitasking
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g
Oligochaete Body Plan• Mainly terrestrial (some freshwater) worms
– No parapodia, & small setae or bristles• Streamline body shape
– Reduced head• No palps
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Hirudinean Body Plan• Body is dorsoventrally flattened
– Anterior and posterior suckers
• Segmentation is reduced to accommodate large blood meals
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Phylum Mollusca• All with a trochophore larval stage• Can be found in all environments marine, freshwater
and terrestrial (moist habitats)• Four major classes
– Class Polyplacophora– Class Gastropoda
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p– Class Bivalvia– Class Cephalopoda
Molluscan Body Plan• Despite this variety all mollusks are
variations on a common theme
1. Muscular foot
2. Mantle
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3. Radula
4. Visceral mass
• A great example of adaptive radiation
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Class Polyplacophora• The chitons
• Muscular foot for crawling
• Flexible 8-piece shell
• Tongue-like radula
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Class Gastropoda• The snails and slugs
• Crawling muscular foot
• Single spiral shell– slugs
T lik d l
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• Tongue-like radula
Class Bivalvia• The clams, scallops, mussels etc.
• Digging foot in some
• Shell in 2 hinged pieces
• No radula
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• The squid & octopi
• Foot modified into tentacles
• Shell reduced or absent
• Beak-like radula
Class Cephalopoda
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5. Type of Body Symmetry?• Most sponges (parazoa) are asymmetrical
– A ‘random’ growth of cells with no plane of symmetry
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5. Type of Body Symmetry?• The ancestral eumetazoan character trait is
radial symmetry– Where there are several planes of symmetry
– Radial animals are divided on an oral-aboral axis
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5. Type of Body Symmetry?• The more derived trait is bilateral symmetry
– Only a single plane creates two ‘equal’ halves• Bilateral animals have multiple axes or ‘sides’
– Anterior – Posterior
– Dorsal – Ventral
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Cephalization• Two major groups of animals
– Radiata– Bilateria
• The concentration of sensory organs at the
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• The concentration of sensory organs at the anterior end
• Clustering of neurons– Ganglia
– Brains
• Complex behaviours
6. Is There a Body Cavity?• The body cavity is called the coelom
– The fluid-filled space around internal organs
– Room for internal organs to expand and move
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• Only looked at in triploblastic animals
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6. Is There a Body Cavity?• Eucoelomate
– A cavity completely lined with mesoderm
• Pseudocoelomate
– A cavity partially lined
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– A cavity partially linedwith mesoderm (and endoderm)
• Acoelomate
– No cavity
– The ‘space’ is completely filled with mesoderm
Animal Phylogeny• The traditional
phylogenetic tree –shared characters– Anatomical features
– Developmental characters
– Embryological characters
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Embryological characters
• New technologies –molecular data– DNA and rRNA sequencing
• Molecular phylogeny
Read Concept 32.4