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Classification of Organisms
1. Aristotle developed 1st classification system
2. Linneaus began the modern system of classification
3. Today we use a phylogenetic classification system
-it uses binomial nomenclature (2 word naming system)
-organisms are classified in a hierarchy of taxa
-kingdom, phylum, class, order, family, genus, specie (from the broadest to the most
specific)
4. Things biologists use to classify organisms are similarities in phylogeny (evolutionary relationships),
structure, development, biochemistry and behavior
5. 5 or 6 Kingdoms
-Monerans – prokaryotes without membrane bound nuclei (bacteria)
-now being divided into 2 kingdoms; archaebacteria and eubacteria
-Protists – eukaryotes without complex organ systems, usually live in water or moist
environments (protozoans, algae, and slime molds)
-Fungi – eukaryotes that obtain food by absorption
-Plants – multicellular eukaryotes that produce own food
-Animals – multicellular eukaryotes that are consumers (lack cell wall)
Viruses
1. History
-in ancient Romevirus meant poison or venomous secretion
-“attack” all kinds of organisms
a. examples of animal viruses, table 21.3
b. most viruses are specie specific
-each type of virus can multiply only in certain hosts
-ex. bacteriophages infect bacteria
-rabies is an exception
-today defined as noncellular infectious agents with 2 characteristics
a. made of only nucleic acids (usually RNA) and proteins
-the protein coat protects the genetic material and helps the virus bind to receptors
on host cell
-genes for many viral proteins mutate at high frequencies
b. cannot reproduce themselves, they need a host cell to accomplish this
2. smaller than bacteria
3. not considered living because they don’t meet the 4 criteria for life, the only thing they “do” is
reproduce and they need a host to accomplish this
4. because they are nonliving, they are not included in the 6 kingdoms and they are not given Latin
names
5. in order for a virus to reproduce, it must first get into a host cell
-this is done by the recognition of and attachment to a specific receptor molecule on the host cell
plasma membrane
-this means that most viruses are specie specific and sometimes even cell type specific, because
they must recognize a certain receptor on the host cell
6. 5 basic steps in viral multiplication
-attachment
-penetration
-replication (synthesis)]
-assembly
-release
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7. they have 2 reproductive cycles (some viruses use only one type, some use both)
-lytic cycle
-attachment to host cell, entry (inject nucleic acid into host cell), replication (host DNA is
destroyed and viral nucleic acid and proteins are produced), assembly (new virus
particles are assembled), lysis and release (the host cell is broken open releasing all of the
newly produced virus)
-usually kills host cell
-lysogenic cycle
-attachment and entry, provirus formation (viral nucleic acid becomes part of host
chromosome), cell division (provirus is inactive/latent but replicated within the host
nucleic acid)
-can go into the lytic cycle at any time when “triggered” (we don’t know exactly what
can trigger the virus), the provirus comes out of the host nucleic acid and begins the lytic
cycle
-page 358
7. non-virus infectious agents;
-viroids (naked strands of RNA)
-mainly cause plant disease
-prions (protein particles)
-ex. Creutzfeldt-Jakob disease (CJD), Kuru, Mad-Cow
Prokaryote (“before nucleus”, no membrane bound organelles) classification
1. General
-most abundant & most far flung kingdom
-longest evolutionary history
-not all “bad”
-small, non-elaborate structure, but they aren’t “simple” or inferior
-not well represented in the fossil record
-classified by comparing traits of new unidentified cells with those of a known group
a. traits usually include: shape, motility, staining attributes, nutritional requirements,
metabolic patterns and endospores (a small asexual spore, as that formed by some
bacteria)
b. the more in common, the closer the relationship is inferred to be
-used to be Monerans, now being considered as 2 separate kingdoms (archaebacteria and
eubacteria)
-remember, early prokaryotes made an important divergence
a. 1 branch led to the eubacteria (most common prokaryotes) and the other branch led to
the archaebacteria and the first eukaryotic cells
-All prokaryotes but they can be aerobic or anaerobic, autotrophs or heterotrophs (parasitic or
saprobic)
-great metabolic diversity
-photoautotrophs – photosynthesis (sunlight as energy, carbon from CO2)
-chemoautotrophs – chemosynthesis (oxidize compounds for energy, carbon from CO2)
-photoheterotrophs – sunlight for energy, carbon from eating other organisms
-chemoheterotrophs – parasites (nutrients from living host) or saprobes (nutrients from
dead)
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2. Size and Shape
-on average, between .5 and 1 micrometer
-since they are so small we measure the “growth” of populations, not individuals
-Bacteria are usually classified by shape (there are variations)
-rods (bacillus)
-spheres (coccus)
-spirals (spirillum)
-see picture page 487
3. Structural Features
-no membrane bound nucleus, most don’t have any membrane bound organelles
-reactions take place in the cytoplasm or at the membrane
-do have cytoplasm, ribosomes, and genetic material (DNA or RNA)
-cell wall – permeable, semi-rigid
-maintain shape, resist rupturing
-staining properties – because of cell wall attributes
-gram positive - purple
-gram negative - pink
-glycocalyx – encloses cell wall
-2 forms
-capsule – highly organized, well attached
-slime coat – less organized, loosely attached
-helps attachment
-helps avoid engulfment
-bacterial flagella
-different structure than eukaryotic flagella
-motility
-rotate like a propeller
-may have 1 or more
-pilli
-short, filamentous proteins that project from cell wall
-helps adhere to surfaces
-helps in attachment
4. Reproduction
-prokaryotic cells nearly double in size, then divide
-they contain a single bacterial chromosome
-circularized, double stranded DNA with only a few proteins attached to it
-some contain and extra piece of DNA – a plasmid
-a small circle of self replicating DNA with a few genes
-a few prokaryotic cells merely “bud” from the parent cell, most undergo prokaryotic
fission
-prokaryotic fission – not the same as binary fission which is a form of asexual reproduction in
some eukaryotes
-steps (page 350)
a. replicates DNA
-both sets of DNA are attached to the plasma membrane
b. synthesizes lipids and proteins to incorporate into the membrane and cell wall
between the 2 DNA’s and move them apart
c. new membrane and wall material grow through the cell midsection to divide
the cytoplasm
d. results in 2 genetically equivalent daughter cells
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-conjugation – transfer of a plasmid between 2 different cells
-donor and recipient cells
-page 351
5. Classification
*Archaebacteria – more ancient type (resemble early cells), inhabit extreme environments.
-Three types:
a. methanogens – strict anaerobes, release methane gas
-live in oxygen free habitats like swamps and the guts of mammals and termites
b. thermofiles – “heat lovers”, do best above 80°C
-nearly all anaerobes that require sulfur
-live in geothermically heated soil, sulfur-rich hotsprings, waste from coal mines,
around volcanoes and hydrothermal vents
c. halophiles – thrive in exceptionally salty habitats (the dead sea and the great salt
lake)
-most aerobic
-some can perform photosynthesis with a unique light absorbing pigment
(bacteriorhodopsin) in the plasma membrane
* Eubacteria – heterotrophs and photosynthetic autotrophs, chemosynthetic autotrophs
-most common bacteria
- they have fatty acids in their plasma membranes and peptidoglycan in their cell walls
a. peptides crosslinked with polysaccharides
- Examples
-Cyanobacteria – autotroph, blue green, in ponds and streams
-streptococcus
-E. coli
-many are decomposers
Evolution and Infectious Disease
*New problems
-emerging pathogens – with world travel, pathogens are easier to spread
-drug resistance
-pathogens in food
-biological weapons
*virusesvaccines, bacteriaantibiotics
Protists
1. Most diverse kingdom, unicellular or multicellular
2. Eukaryotes, heterotrophs, autotrophs and some get nutrients from decaying
organic matter
3. Three types – grouped by feeding types
A. Protozoans – animal like, unicellular, heterotrophs
B. Algae – plant like protist, unicellular & multicellular, photosynthetic
-Have no roots, stems or leaves
-Known as phytoplankton (Photosynthetic protists)
-Major producers in aquatic ecosystem
-Classified into six phyla by pigments, food storage and cell wallstructure
– Most are different colors because of chlorophyll and different pigments
C. Fungus-like protist –obtain energy from decaying organic material, live in cool moist places
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See Attached Detailed Chart
Kingdom – Protista, Summary
3 types
Phyla
Description
Protozoan (animal-like) Grouped by movement
-unicellular,
-sarcodina
-move with pseudopods
heterotrophs
-zoomastigina
-move with flagella
-ciliophora
-move with cilia
-sporozoans
-do not move
(apicomplexa)
Algae (plant-like)
Grouped by pigment
-photosynthetic
and cell wall
-no true roots, stems
-euglenophyta
-autotrophic and
or leaves
heterotrophic, no cell
-unicellular and
wall
multicellular forms
-bacillariophyta
-silica shells, little box
-dinoflagellates
-flagella, red tides
-rhodophyta
-marine, tropical
-phaeophyta
-marine, cool
-chlorophyta
-freshwater
Fungus-like
-decomposers
-myxomycota
-mass of cytoplasm
with no cell walls or
membranes; many
nuclei
-acrasiomycota
-mass of separate cells
with individual nuclei
-oomycota
-vary
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Examples
-amoebas, foraminiferans, radiolarians
-flagellates,
-paramecium
-plasmodium (malaria)
-euglena
- diatoms
-red algae
-brown algae, kelp
- green algae, volvox, spirogyra
-plasmoidial slime molds
-cellular slime molds
-water molds and downy mildew
Fungi
-look up key terms
1. live by decomposing living and nonliving organic matter
2. the basic structural units of fungi are hyphae (thread-like filaments) that grow to form mycelia (mass
of interwoven hyphae)
-hyphae have chitin containing cell walls that may or may not be divided into individual cells by
septa (partitions between hyphae)
3. they are heterotrophs that carry out extracellular digestion
4. they can be a saprobe, a parasite, or a mutualist in a symbiotic relationship
5. most fungi produce asexual and sexual spores
6. the way in which spores are produced is the basis for fungal classification
7. fungi play an indespensible role in deocmposing organic material and recycling nutrients
8. lichen is a symbiotic relationship of a fungi and an algae or cyannobacteria
9. certain fungi associate with the plant roots to form mycorrhizae, a relationship in which both plants
and fungi benefit
Kingdom - Fungi
Phylum or Division Description
Example
Pictures of sexual reproduction
Zygomycota
Form zygospores during
Molds, Rhizopus
sexual reproduction
(bread mold)
Ascomycota
Sac fungi, form ascospores
during sexual reproduction
Yeast, morels, truffles
Basidiomycota
Club fungi, form
basidiospores during sexual
reproduction
Mushrooms, puffballs,
shelf fungi
Deuteromycota
Imperfect fungi, unknown
sexual reproduction
Form symbiotic relationships
with species of other
kingdoms
Penicillium,
aspergillus
Lichen, mycorrhizae
Symbionts
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Kingdom - Plantae (Plants)
1. eukaryotic, multicellular autotrophs (photosynthetic), most with true roots, stems and leaves, and all
have the ability to prevent dessication of their embryos, nonmotile, but do “respond to stimuli”,
2. plants are classified into divisions (same as phyla, see below)
3. alteration of generations
4. phylogenetic tree
a. see page 387, fig. 23.3
b. pictures attached
Phylum
Description
(division)
Bryophytes
Nonvascular spores
Simplest plants; no true
roots, stems or leaves;
Bryophyta
water is major limitation
in size and reproduction;
Hepatophyta
small, moist habitat,
sperm must swim to egg;
Anthocerophyta
predominantly haploid
Sphenophyta or
Vascular
Spores
hollow jointed stems
Arthrophyta or
with scalelike leaves
Equisetophyta
Psilophyta
vascular
spores
Thin green leafless stems
Lycophyta
vascular
Spore
Pterophyta
vascular
Spore
Cycadophyta
vascular
seeds in Short palm-like trees
cones
with scaly trunks, male
and female cones on
separate trees
Gnetophyta
vascular
Seeds in Only 3 genera
cones
Ginkophyta
vascular
Seeds in Only one specie, tree
cones
with fan shaped leaves
Coniferophyta
vascular
seeds in Conifers, needles or scaly
cones
leaves, male and female
cones on same tree
Anthophyta
vascular
seeds in Flowering plants, 2
(angiosperms)
fruit
classes (monocotyledons
and dicotyledons),
“coated seeds”
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Examples
Mosses, liverworts, hornworts
Mosses
Liverworts
Hornworts
Horsetails
“whisk ferns”
Club mosses
Ferns
Gnetum, ephedra, welwitschia
Ginko biloba
Pines, firs, cypress, redwood
Apple trees, roses, violets
Kingdom Animalia
More than 30 phyla, we will look at 9 major
I. General Characteristics
A. Multicellular – nearly all have tissues, organs and organ systems
B. most are motile during at least part of their life cycle
C. aerobic, heterotrophic, reproduce sexually and some also asexually, life cycles with the adult is
always diploid, embryo has specific stages of development, originated late in the Precambrian Era, more
than 2 million modern species, less than 50,000 are vertebrates
II. Variation in Body Plans
A. Symmetry
1. Assymetry
2. Radial – body parts arranged regularly around a central axis
-live in water
3. Bilateral – body axis passing from anterior end to posterior end
-Key terms
-anterior – front, head area
-posterior – back, tail end
-dorsal – back side
-ventral – underside, “belly” side
-Advantage – paired body organs
-Cephalization – sensory parts and nerve cells in head
B. Gut Type
1. gut - sac projecting into the body or part of a tube through the body, digestive tract
2. 2 types
-“sac like” gut – single opening, mouth, food in and out same opening
-“tubular” gut – two openings, mouth and anus, specialized regions, complete digestive
system, sometimes referred to as a tube within a tube, allows for specialization of parts
along the tube
C. Tissue Complexity
1. Parazoa – no tissue, no organs, cellular level only
2. Eumetazoa – tissue organization
-number of germ layers
-diploblastic – 2
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-triploblastic – 3
a. ectoderm – outer layer of cells, gives rise to skin and nervous system
b. mesoderm – middle layer of cells, becomes muscles, skeleton, connective
tissue, kidneys, circulatory and reproductive organs
c. endoderm – inner layer of cells, will form the lining of the gut and major
organs derived from it
D. Segmentation
1. repeating series of body units
2. body parts modified and adopt specialized functions
E. Body Cavities (see picture page 417) – the space that separates the gut and internal organs from the
rest of the body, it isolates the internal organs from body wall movements, it also bathes the internal
organs in a liquid through which nutrients and waste can diffuse
1. Acoelomate – no body cavity
2. Pseudocoelomate – “false” body cavity, a body cavity between the endoderm and mesoderm
3. Coelomate – true body cavity, has peritoneum (lining that encloses organs in the coelom),
favors increase in size, protects and cushions internal organisms, allows organs to move
separately from the body wall, located within the mesoderm
-types of coelomates: protostomes and deuterstomes
-differ in embryo development: cleavage type, opening to internal cavity
(archenteron), and how the coelom develops
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-Protostomes
a. spiral cleavage
b. first opening in embryo becomes mouth
c. coelom forms from spaces that open in mesoderm
-Deuterostomes
a. radial cleavage
b. first opening in embryo becomes anus
c. coelom forms from outpouching of gut wall
F. Circulatory System
1. open circulatory system Blood is pumped by a heart into the body cavities, where tissues are
surrounded by the blood. the blood diffusing back to the circulatory system between cells.
2. Closed circulatory systems have the blood closed at all times within vessels of different size
and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does
not normally fill body cavities.
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III. Invertebrate Phyla
A. Porifera -sponges
B. Cnidaria
C. Platyhelminthes – flatworms
D. Nematoda – roundworms
E. Annelida – segmented worms
F. Mollusca
G. Arthropoda – “jointed appendages”, largest animal phyla
H. Echinodermata
page 782 for summary of invertebrates
Phylum Chordata
I. Invertebrate Chordates (Hemichordates)
A. Urochordates – tunicates, sea squirts (p446)
B. Cephalochordates – lancelets (p447)
III. Vertebrate Chordates
Vertebrate Classes
Fish –
I. Agnathans – jawless fish
A. scavengers, parasites or filter feeders
II. Gnathostomates – jawed fish
A. class Chondrichthyes – cartilaginous
B. class Osteoichthyes – bony
Tetrapods – four limbs
I. class Amphibia – Amphibians
II. class Reptilia – Reptiles
A.amniotic egg
-shell (leathery in reptiles) to prevent drying out
-extra-embryonic membranes
1. amnion; encloses “fluid/private pool” to keep embryo from drying out
2. allantois; stores waste
3. chorion; gas exchange
4. yolk sac; provides nutrients
5. albumin; protein food source
III. class Aves – birds
IV. class Mammalia - Mammals
Types of “birth”
-oviparous – lay eggs and hatch outside of mother (birds, amphibians)
-viviparous – embryos draw nutrients from mother and are born “live” (most mammals)
-ovoviviparous – embryos develop within the mother, but receive nutrients from yolk sac, then
are born live (some snakes, lizards and sharks)
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Phylum
Porifera
Type/Subphylum/Class
Invertebrate -three
taxonomic classes
based on the chemical
composition of their
skeletons.
- Calcarea with
skeletons made of
calcium carbonate
- Hexactinellida with
skeltons composed of
silicon dioxide
- Demospongiae with
skeletons made from
protein fibers
Cnidarian
Invertebrate
4 main classes
-hydrozoans –
portugese man of war,
siphonophores, hydras,
fire corals (many
colonial)
Characteristics
*no body symmetry, cellular level of body
structure (parazoa),
*sessile filter feeders, no gut,
*sexual reproduction (release sperm into the
water, but retain fertilized egg and embryo),
* asexual reproduction by fragmentation or
gemmules,
*sponge body plan (pores, spicules,
amoebocytes, collar cells) -The body wall is
approximately two cell layers thick with a gel like
substance in-between. -The body wall is
perforated by many pores and channels through
which water enters the animal, passing into the
spongocoel (the empty middle), and exiting it
through a large opening, the osculum.-There are
no organs or appendages and digestion is
intracellular (within cells). -The outer layer is
made up of flattened cells with numerous pores
throughout. -The middle layer of cells contains
mobile cells as well as the skeletal cells which
give the sponge its shape. The skeletal cells are
tough protein fibers or sharp glass-like spicules.
The mobile cells are called amoebocytes. These
cells are able to move by use of pseudopodia.
They are constantly moving, and their main
function is to pick up food vacuoles from the
choanocytes, digest the food inside them, and
carry the nutrients to the cells that need them.
However, they also function to carry oxygen to
other cells, dispose of waste products, maintain the
structure of the sponge, and even change into
another cell type if they have to. -The third,
innermost layer is made completely of cells called
choanocytes, or collar cells, which trap food and
move water.
*radial symmetry, tissue level of body structure
(eumetazoa), 2 germ layers, simple nervous
system; nerve net, no brain to control, 2 body
stages (-polyps – sessile, asexual reproductionmedusa - floating umbrella shaped body, sexual
reproduction), mesoglea – jelly-like material ,
stinging cells with nematocysts, incomplete
digestive tract
-scyphozoans - true
jellyfish
-anthozoans – corals,
anemones sea pens
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Examples
sponges
jellyfish, coral,
sea anemone,
hydra
Platyhelminthes
Flatworms
-cubozoa, - box jellies
with complex eyes and
potent toxins
Invertebrate.
3 main classes
-cestoda – tapeworms
(parasitic)
-trematoda – flukes
(parasitic)
Nematoda
Roundworms
Annelida
Segmented
worms
-turbellaria – planaria
(free living)
Invertebrate
Invertebrate
3 main classes
-hirudinae – leeches,
front and rear suckers,
no setae, anesthetic
and aticoagulants
-polychaeta – bristle
worms
-oligochaeta – earth
worms
Mollusca
Invertebrate
3 main classes
-gastropods – “belly
foot” single or no
shell, examples; snail,
slugs, conchs,
nudibranchs
*bilateral symmetry, tissues, organs and systems
Tapeworms,
level of body structure (eumetazoa), 3 germ layers, flukes, planaria
defined head, protonephridia and flame cell –
excrete water, incomplete digestive system,
acoelomates, tapeworms - proglottids (body units),
scolex (“head” with suckers, hooks or both),
sexual reproduction - hermaphroditic (both male
and female in same organisms), asexual
reproduction – regeneration, ladder type nervous
system
*bilateral symmetry, tissues, organs and systems
level of body structure (eumetazoa), 3 germ layers,
free living or parasitic, complete digestive system,
psuedocoelomates, sexual reproduction with
separate sexes, tough, protective, flexible covering
called a cuticle
*bilateral symmetry, coelomates (protostomes),
complete digestive system with a crop (storage) &
gizzard (a sac with muscular walls and hard
particles for mashing), simple nervous system,
rudimentary brain and ventral nerve cord, closed
circulatory system with a primitive heart,
segments allow for specialization of body parts,
setae, chitin reinforced bristles, eumetazoa, 3 germ
layers, enclosed in a flexible cuticle of secreted
material (slime), good for gas exchange, but not
for water conservation, hydrostatic skeleton (fluid
cushioned coelomic chambers), nephridia, sexual
reproduction, hermaphroditic
ascarids,
hookworms,
trichinella, pin
worms
Leeches and
earthworms
*bilateral symmetry, coelomates (protostomes),
Snails, clams,
complete digestive system, eumetazoa, 3 germ
octopus
layers, basic structure – soft body, muscular foot,
mantle (tissue that drapes like a skirt over the body
mass), visceral mass (organs), some with shells,
sexual reproduction; most separate sexes except
gastropods, circulatory system open except in
cephalopods closed
-bivalves – 2 shells
with hinge, examples;
clams, oysters,
mussels, scallops
-cephalopods – “head
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Arthropods
foot”, sharp eyes,
tentacles, jet propelled,
complex brains, closed
circulatory system.
ex; squid, octopus,
cuddle fish, chambered
nautilius (full shell)
Invertebrate
main classes
-trilobites - extinct
-chelicerates
(subphylum)
-merostomates
– horseshoe crabs
5 pairs of legs,
marine
-arachnids –
spiders, mites,
scorpions, ticks
4 pairs of legs,
a pair of
pedipalps, a pair
of chelicerae,
spinnerettes
-uniramia
(subphylum)
-insects
3 pairs of legs,
1 pair
antennae, 3
body
segments,
some with
wings
*jointed appendages, bilateral symmetry,
coelomates (protostomes), complete digestive
systems, eumetazoa, 3 germ layers, exoskeletons
(a cuticle of chitin, proteins and surface waxes
often impregnated with calcium carbonate
deposits) that molt, segmented bodies (some many
segments, some head/thorax/abdomen, some
cephalothorax/abdomen), efficient respiratory
structures – depending on environment and type (gills, aquatic-tracheal tubes with spiracle
openings, insects-book lungs, spiders), Nervous
system-double ventral nerve cord, anterior brain,
ganglia (groups of nerve cells), acute senses
(antennae, compound eyes, pheromones), open
circulatory system with vessels and heart(s),
malphigian tubes for waste excretion, some have
asexual reproduction – parthenogenesis, where
organism develops from unfertilized egg, some
are helpful others are harmful to humans,
metamorphosis (complete – egg/larva/pupa/adult
and incomplete – egg/nymph/adult), usually
separate sexes, some hermaphrodites
-chilopods –
centipedes
a. flat bodied,
predatory, all
but 2 segments
with 1 pair of
walking legs,
fangs and
venom glands
-diplopods –
millipedes
2 pair of legs
per segment,
scavengers,
body usually
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Bees, spiders,
crabs, mites,
centipedes
cylindrical
-crustaceans
-most aquatic,
gills,mandibles,
5 pairs of
walking legs, 2
pair of
antennae, 2 to 3
body segments
-crabs, lobster, shrimp,
pill bugs, barnacles
Echinoderms
Invertebrate
5 main classes
-opiuroids – brittle
stars, use slithering
motion instead of tube
feet
-asteroids – starfish, 5
– 46 rays
-holotheroids – sea
cucumbers
*spiny skinned, marine animals, adults, radial
symmetry – larval stage, bilateral symmetry,
pedicillaria (skin pinchers), asexual reproduction
– regeneration, sexual reproduction, watervascuale system for movement, madreporite (lets
water in), tube feet, coelomates (deuterstomes),
eumetazoa, complete digestive system, internal
skeleton, composed of calcium carbonate and
other substances excreted from specialized cells,
simple nervous system; nerve net and nerve rings,
most without sensory organs, some with light
sensitive eyespot
-echinoids – sand
dollars and sea urchins
-crinoids – sea lilies
and feather stars
-only sessile
echinoderms
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Starfish, sea
cucumbers,
sand dollars, sea
urchins
Chordates
*eumetazoa with 3 germ layers, bilateral
symmetry, complete digestive tract with 2
openings (mouth and anus), coelomates that are
deuterostomes, notochord: a long dorsal rod of
stiffened tissue (can be replaced by cartilage or
bone in vertebrates), Dorsal Hollow Nerve Cord:
a bundle of nerves housed in a fluid filled canal,
anterior end develops into brain posterior develops
into spinal cord, Pharyngeal Pouches: gill slits (at
least at the embryonic stage), 3 pairs – Eustachian
tubes, tonsils, thymus and parathymus), Internal
skeleton: endoskeleton, post-anal tail
Invertebrate
Urochordates
-Tunicates, sea
squirts (p774)
-lancelets
(p773)
Cepalochordates
Vertebrate
Fish
*have all chordate characteristics, notochord
replaced by vertebral column, paired appendages,
high degree of cephalization, closed circulatory
system, efficient respiration and excretion
*cold blooded, 2 chambered heart, scales and gills
Agnathans
*jawless, lack bony skeleton
Chondricthyes
*cartilage skeleton, placoid scales, lateral line
system – series of pressure sensitive cells, sense
pressure, gills uncovered (5-7 gill slits)
Osteoicthyes
*skeleton of bone, operculum - cover gills, swim
bladder – gas filled sac whose pressure can be
altered to change buoyancy, scales formed by
bone, ray-finned fish, lobed-fin fish, lung fish
Amphibians
*smooth, nonscaly skin (moist), small
underdeveloped lungs, 3 chambered heart
(poikilotherms – mixing of oxygenated and
deoxygenated blood), need water for fertilization,
eggs not water tight, ectothermic – body
temperature depends on environmental sources,
cloaca – enlarged duct that delivers feces,
excretory and reproductive products (1 opening),
metamorphosis,
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*Lampreys &
hagfish
*sharks, skates,
rays and
chimaeras (rat
fish)
*trout, perch,
bass, salmon,
tuna
*salamander,
frog, toads,
caecilian
(legless)
Reptiles
*internal fertilization, amniotic egg, thick scaly
skin with keratin (water proof protein) that molts,
well developed lungs, nearly 4 chambered heart
(poikilotherms – mixing of oxygenated and
deoxygenated blood), ectothermic, cloaca – body
temperature depends on environmental sources,
moved to land; totally independent of water,
kidneys – excrete uric acid
* crocodiles – 4 chambered heart
* Jacobson’s organ: sensory structure in snakes
* Carapace – turtle shell
* tortoise: land
*turtles, snakes,
lizards and
crocodilians
Aves
*feathers, endothermic – warm blooded, 4
chambered heart, cloaca, amniotic egg (hard shell)
*chicken,
cardinal, ostrich
Mammals
3 orders
*hair, endothermic, mammary glands, 4
chambered heart, dentition (teeth), care for young
monotremes
– egg laying mammals
-platypus and
spiny ant-eater
marsupials
-pouched mammals
eutherians
-placentals
-koala and
kangaroo
-bats, manatees
and humans
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