Post on 18-Dec-2015
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Systematics
• The study of biological diversity and classification
• classification of living organisms by evolutionary relationship
Classification
• Carolus Linnaeus (1707-1778) – Swedish naturalist
• Developed the modern taxonomic classification system
Linnean System of Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Chordata
Mammalia
Primates
Hominidae
Gorilla
Gorilla gorilla
Revised Linnean SystemDivision KingdomPhylum
SubphylumSuperclass
ClassSubclassInfraclass
OrderSuperfamily
FamilySubfamily
GenusSpecies
Subspecies
EukaryaAnimaliaChordata
VertebrataTetrapodaMammalia
Theria EutheriaPrimates
AnthropoideaHominidaePonginaeGorilla
Gorilla gorillaGorilla gorilla beringei
Binomial Nomenclature
• Genus + species• Examples:
– Rana catesbeiana: bull frog– Turdus migratorius: American robin– Homo sapiens: modern human– Mucosa domestica: house fly
• Subspecies sometimes included– Gorilla gorilla beringei: mountain gorilla
What is an Animal
• Eucaryotic – cells divided into organelles
• Multicellular
• Heterotrophic– do not produce own nutrients
• Lack cell walls
• Tissues linked by proteins (e.g. collagen)
What is an Animal
• Cells often linked by cell junctions– gap, adhesion, tight
• Possess electrogenic cells – nerve cells and muscle cells
• Reproduce sexually (diploid)– sperm + egg → zygote → blastula → gastrula
→ larva → adult
Major Evolutionary Divergences Among Animals
• Development of Tissues• Development of Body
Plans• Development of Body
Cavities• Developmental Origin
of the Coelom
Development of Tissues
• Development of aggregations of similar cells into patterns and layers
• Parazoa (sponges) – lack tissues
• Eumetazoa – possess tissues
Development of Body Plans
• Pattern of body and structure• Number of embryonic cell layers• Radiata (e.g. jellyfish, hydra)
– radial symmetry
– diploblastic (2 germ cell layers)
• Bilatera (everything else)– Blateral symmetry
– Triploblastic (3 germ cell layers)
Development of Body Cavities
• Acoleomates (flatworms)– no body cavities
• Pseudocoelomates (rotifers, roundworms)– body cavity not surrounded by
mesoderm (pseudocoelom)
• Coleomates (everything else) – body cavity enclosed by
mesoderm (coelom)
Developmental Origin of the Coelom
• Coelomates are divided into two gorups based upon:
1. Pattern of cell cleavage during early development
2. When cell developmental fate is determined
3. How the coelom is formed
4. How the digestive tract is formed during gastrulation
Protostomes
• Mollusks, earthworms, insects, etc.
• Spiral cleavage– cell division diagonal to vertical axis
• Determinant cleavage– development into tissues determined
very early in cleavage
• Schizocoelous– coelom forms by splitting solid
masses of mesoderm in
• Blastopore forms mouth
Deuterostomes
• Starfish, vertebrates• radial cleavage
– cell division at right angles to vertical axis
• indeterminant cleavage– development into tissues determined
later in cleavage
• enterocoelous – coelom forms by mesoderm layer
budding from archenteron
• blastopore forms anus
Parazoa:Phylum Porifera
• sponges• little cell differentiation• sessile • no nerve or muscle cells• porous body
– enables water circulation through the body
– flow driven by choanocytes– food collected and digested
by amoebocytes
Radiata:Phylum Cnidaria
• Corals, jellyfish, anemones, corals
• gastrovascular cavity– central compartment
with single opening
• two basic body plans:– polyp – usually sessile– medusa – motile form
Radiata:Phylum Cnidaria
• tentacles arranged around opening to the gastrovascular cavity
• lined with nematocysts– stinging cells
• possess nerve cells forming nerve net– no central nervous system
• possess muscle-like cells
Radiata:Phylum Ctenophora
• Comb jellies• Similar in appearance to
jellyfish• Possess comb-like plates
of cilia used for locomotion
• Collect food with tentacles covered with colloblasts (lasso cells)
Acoelomates:Phylum Platyhelminthes
• Flatworms
• gastrovascular cavity with one opening
• true muscle tissue
• primitive excretory system (water balance)
• sensory organs in head (photoreceptors, chemoreceptors)
• central nervous system (ganglia in head w/ ventral nerve cords)
Acoelomates:Phylum Platyhelminthes
• Major Classes– Turbellaria
• planarians (free living)
– Monogenea and Tremotoda
• flukes (parasites)
– Cestoidea • tapeworms (parasites)
Pseudocoelomates:Phylum Rotifera
• Rotifers• complete digestive tract
– separate mouth and anus
• pseudocoelomic fluid acts as circulatory system
• cilia lining crown draw water into the mouth
Pseudocoelomates:Nematoda
• Nematodes (roundworms)• complete digestive tract• pseudocoelomic fluid acts
as circulatory system• longitudinal muscle
orientation• aquatic habitats, soils,
plant and animal parasites
Protostome Coelomates:Phylum Nemertea
• Proboscis worms• acoelomous body, except
for fluid-filled sac used to extend proboscis
• similar excretory, sensory and nervous systems to flatworms
• complete digestive tract• closed circulatory system
(blood confined to vessels)
Protostome Coelomates:Lophophorate Phyla
• possess lophophore– ciliated fold around
mouth
• no head
• U-shaped digestive tract
Protostome Coelomates:Lophophorate Phyla
• Bryozoans – sessile, resemble
moss, hard exoskeletons
• Phoronids – horseshoe worms
• Brachiopods– resemble bivalves
Protostome Coelomates:Phylum Mollusca
• Mollusks• Major Classes:
– Class Polyplacophora• chitons
– Class Gastropoda • snails and slugs
– Class Bilvalvia • clams, oysters, mussels, etc.
– Class Cephalopoda• octopus, squid, nautiluses
Protostome Coelomates:Phylum Mollusca
• Muscular foot• visceral mass
– contains organs
• gills (respiration)• complete digestive tract w/
specialized organs• open circulatory system
(blood not confined to vessels)
• mantle– covers visceral mass, secretes
shell
Protostome Coelomates:Phylum Annelida
• Annelids (segmented worms)• hydrostatic skeleton• coelom in repeating segments
with alternating longitudinal and circular muscles, setae, and metanephridia (excretion)
• closed circulatory system• several specialized regions in
digestive tract• cerebral ganglia with ventral
nerve cord
Protostome Coelomates:Phylum Annelida
• Major Classes– Class Oligochaeta
(earthworms)– Class Polychaeta
(polychaetes)– Class Hirudinea
(leeches)
Protostome Coelomates: Phylum Arthropoda
• specialization of body segments– specialized limbs, etc.
• hard exoskeleton– protein and chitin
• high cephalization of sensory organs
• open circulatory systems– blood (hemolymph) not
confined to vessels
Arthropods:Chelicerates
• claw-like feeding appendages (chelicerae), lack antennae
• Class Arachnida (spiders, scorpions, ticks, mites)– 2 body segments (cepahlothorax and
abdomen)– 6 pairs of appendages
• chelicerae, pedipalps, 4 pr walking legs extend from cephalothorax
– book lungs• enhances gas exchange btw hemolymph
and air
Arthropods:Uniramians
• jaw-like feeding appendages (mandibles), 1 pair of antennae, unbranched appendages
• Class Diplopoda – millipedes • Class Chilopoda – centipedes• Class Insecta – insects
– three body segments (head, thorax, abdomen)
– many possess wings– specialized digestive system– Malpighian tubules (excretion)– tracheal system (respiration)
Arthropods:Crustaceans
• mandibles, 2 pair of antennae, branched appendages
• Class Crustacea– possess gills– salt glands (hemolymph salt
balance)
• Groups– Isopods (e.g. pill bugs)– Copepods (e.g. Cyclops)– Decapods (crabs, lobsters, etc.)
Deuterostome Coelomates :Phylum Echinodermata
• sea stars, sea urchins, sea cucumbers
• adults have radial symmetry– bilateral larvae
• endoskeleton of hard plates
• water vascular system– used to manipulate tube
feet
Deuterostome Coelomates :Phylum Chordata
• Lancelets tunicates, vertebrates• Characteristics of embryos:
1. possess notochord• longitudinal, flexible rod between
digestive tract and nerve cord
2. possess dorsal hollow nerve cord
3. have pharyngeal slits• modified for gas exchanges, jaw
support, hearing, etc.
4. have muscular postanal tail
Invertebrate Chordates
• Subphylum Urochordata– tunicates– sessile marine animals– chordate characters seen
only in larvae
• Subphylum Cephalochordata – lancelets
Subphylum Vertebrata• Characteristics
– neural crest formation during embryonic development
– vertebral column + skull– pronounced cephalization of sensory and neural
apparati– closed circulatory system
• Agnathans– lack hinged jaws, notochord present throughout
life
• Gnathostomes– possess hinged jaws, notochord replaced by
vertebrae, paired appendages
• Tetrapods– Possess two pairs of appendages
Superclass Agnatha
• lack hinged jaws,• notochord present
throughout life• no paired appendages• lampreys and hagfish
Superclass Gnathostoma:Jawed Fish
• Class Chondrichthyes– Sharks, rays
– cartilaginous skeletons
• Class Osteichthyes – bony fish (bone skeletons)
– Subclass Actinopterygii • Ray-finned fish
– Subclass Sarcopterygii• Lobe-finned fish
Superclass Tetrapoda:Class Amphibia
• Characteristics– tetrapods (4 limbs)- terrestrial
movement– aquatic larval stage– moist, permeable skin
• Anurans– frogs and toads
• Urodeles– salamanders and newts
• Caecilians– legless, fossorial amphibians
Superclass Tetrapoda:Class (?) Reptilia
• Reptiles• Scaly, impermeable skin• Amniotes
– Lay shelled amniotic eggs
• Chelonians (Testudines)– Turtles
• Lepidosaurians– Tuatara, snakes, lizards
• Archosaurs– Crocodilians, dinosaurs, birds
Superclass Tetrapoda:Class Aves
• Birds• Amniotes• Possess feathers• Possess wings (flight)• Endothermic
– most body heat generated internally
• Two-circuit circulatory system
Superclass Tetrapoda:Class Mammalia
• Mammals• Possess hair• Possess mammary glands• Endothermic• Two-circuit circulatory system• Most give birth to young
(amniotic)• Diaphragm for active ventilation
of lungs