bio22 4th post lab discussion
DESCRIPTION
for bio22 under Ms. Manahan UP ManilaTRANSCRIPT
4th Post lab discussionBio22 LManahan
Embryology
Development of embryo Fertilization Cleavage Gastrulation Neurulation Organogenesis
Fertilization
Fertilization membrane Hardened vitelline membrane to prevent further
sperm penetration
Perivitelline space Grey crescent
Jelly coats1. It prevents too many sperm from getting to
the egg at the same time, because of its viscosity.
2. Proteins in the jelly initiate the acrosome reaction in sperm so they are ready to fertilize the egg.
3. It provides a sort of "shock absorber" to prevent injury .
Figure 32.1 Early es,mbryonic development (Layer 1)
Cleavage is a series of rapid mitotic divisions (without cell growth)
Cleavage partitions the cytoplasm of one large cell Into many smaller cells called blastomeres
Figure 47.7a–d
Fertilized egg. Shown here is thezygote shortly before the first cleavage division, surrounded by the fertilization envelope. The nucleus is visible in the center.
(a) Four-cell stage. Remnants of the mitotic spindle can be seen between the two cells that have just completed the second cleavage division.
(b) Morula. After further cleavage divisions, the embryo is a multicellular ball that is stillsurrounded by the fertilization envelope. The blastocoel cavityhas begun to form.
(c) Blastula. A single layer of cells surrounds a large blastocoel cavity. Although not visible here, the fertilization envelope is still present; the embryo will soon hatch from it and begin swimming.
(d)
These cells are pluripotent (have the potential to become ANY of the 220 types of cells in the human body). These are embryonic stem cells
Which is holoblastic and which is meroblastic?
The development of body axes in frogs Is influenced by the polarity of the egg
Figure 47.8a, b
Anterior
Ventral
Left
Posterior
Dorsal
Right
Body axes. The three axes of the fully developed embryo, thetadpole, are shown above.(a)
Animalhemisphere
Animal polePoint ofsperm entry
Vegetalhemisphere Vegetal pole
Point ofspermentry Future
dorsalside oftadpoleGray
crescentFirstcleavage
The polarity of the egg determines the anterior-posterior axis before fertilization.
At fertilization, the pigmented cortex slides over the underlyingcytoplasm toward the point of sperm entry. This rotation (red arrow)exposes a region of lighter-colored cytoplasm, the gray crescent, which is a marker of the dorsal side.
The first cleavage division bisects the gray crescent. Once the anterior-posterior and dorsal-ventral axes are defined, so is the left-right axis.
(b) Establishing the axes. The polarity of the egg and cortical rotation are critical in setting up the body axes.
1
2
3
The mechanics of gastrulation in a frog
Figure 47.12
SURFACE VIEW CROSS SECTIONAnimal pole
Blastocoel
Dorsal lipof blastopore
Dorsal lipof blastoporeVegetal pole Blastula
Blastocoelshrinking
Archenteron
Blastocoelremnant
EctodermMesoderm
Endoderm
GastrulaYolk plugYolk plug
Key
Future ectoderm
Future mesoderm
Future endoderm
Gastrulation begins when a small indented crease, the dorsal lip of the blastopore, appears on one side of the blastula. The crease is formed by cellschanging shape and pushing inward from the surface (invagination). Additional cells then rollinward over the dorsal lip (involution) and move intothe interior, where they will form endoderm andmesoderm. Meanwhile, cells of the animal pole, the future ectoderm, change shape and begin spreading over the outer surface.
The blastopore lip grows on both sides of the embryo, as more cells invaginate. When the sides of the lip meet, the blastopore forms a circle thatbecomes smaller as ectoderm spreads downward over the surface. Internally, continued involutionexpands the endoderm and mesoderm, and the archenteron begins to form; as a result, the blastocoel becomes smaller.
1
2
3Late in gastrulation, the endoderm-lined archenteron has completely replaced the blastocoel and the three germ layers are in place. The circular blastopore surrounds a plug of yolk-filled cells.
Organogenesis
Various regions of the three embryonic germ layers Develop into the rudiments of organs
during the process of organogenesis
Neurulation
Early in vertebrate organogenesis The notochord forms from
mesoderm and the neural plate forms from ectoderm
Figure 47.14a
Neural plate formation. By the timeshown here, the notochord has developed from dorsal mesoderm, and the dorsal ectoderm hasthickened, forming the neural plate, in response to signals from thenotochord. The neural folds arethe two ridges that form the lateral edges of the neural plate. These are visible in the light micrographof a whole embryo.
Neural folds
1 mmNeuralfold
Neuralplate
NotochordEctoderm
MesodermEndodermArchenteron
(a)
LM
The neural plate soon curves inward Forming the neural tube
Figure 47.14b
Formation of the neural tube. Infolding and pinching off of the neural plate generates the neural tube. Note the neural crest cells, which will migrate and give rise to numerousstructures.
Neuralfold
Neural plate
Neural crest
Outer layer of ectodermNeural crest
Neural tube
(b)
Mesoderm lateral to the notochord Forms blocks called somites
Lateral to the somites The mesoderm splits to
form the coelom
Figure 47.14c
Somites. The drawing shows an embryoafter completion of the neural tube. By this time, the lateral mesoderm hasbegun to separate into the two tissuelayers that line the coelom; the somites, formed from mesoderm, flank thenotochord. In the scanning electron micrograph, a side view of a whole embryo at the tail-bud stage, part of the ectoderm has been removed, revealingthe somites, which will give rise to segmental structures such as vertebrae and skeletal muscle.
Eye Somites Tail bud
1 mmNeural tube
Notochord Neuralcrest
Somite
Archenteron(digestive cavity)
Coelom
(c)
SEM
neurula
Level of telencephalon
Level of eyes
Level of heart
http://www.uoguelph.ca/zoology/devobio/57mmfrog/db57fg11.htm
Level of midgut
Level of hindgut
GENETICS
Vocabulary
Genetics: The scientific study of heredity Allele: Alternate forms of a gene/factor. Genotype: combination of alleles an organism
has. Phenotype: How an organism appears. Dominant: An allele which is expressed (masks
the other). Recessive: An allele which is present but
remains unexpressed (masked) Homozygous: Both alleles for a trait are the
same. Heterozygous: The organism's alleles for a trait
are different.
Composition of DNA
The structure of DNA was discovered by Watson and Crick in 1953.
It is a twisted double helix molecule, containing sugar, phosphates, and nitrogenous bases.
The sugar is deoxyribose and the phosphoric acid molecules are always the same and provides for the structure (side of the ladder).
The only difference between us is the order and arrangement of the four bases (rungs of the ladder).
Bases of DNAAdenine= AThymine= TGuanine= GCytosine= CA always pairs with TC always pairs with G
Bases of RNAAdenine= AUracil= UGuanine= GCytosine= CG always pairs with CT from the DNA = A in the RNAA from the DNA = U in the RNA
DNA Model
ChromosomesThe DNA in every cell is located in
rod like segments called chromosomes
Chromosomes occurs in pairs in every cell of our body except in the sperm and ovum.
Chromosomes numbers are the same for each specie.
Chromosome Numbers
Species Diploid # Haploid #
Cattle 60 30Swine 38 19Sheep 54 27Horse 64 32Human 46 23Chicken 78 39Goat 60 30Donkey 62 31
Chromosomes
There are 2 sex chromosomes included in the diploid number of the chromosomes.
All of the other chromosomes are referred to as autosomes.
In mammals if the sex chromosomes are alike, XX it results in a female.
If the sex chromosomes are different, XY it results in a male.
Sex Determination Females contribute an X chromosome
towards the sex of their offspring. Males can contribute an X or a Y
chromosome toward the sex of their offspring.
Absence of an Y chromosome results in a the embryo developing into a female.
Presence of an Y chromosome results in the embryo developing into a male.
Sex Determination Gametogenesis =
Formation of gametes through meiosis.
Male = 4 viable spermatids
Female = 1 viable ovum, 3 polar bodies.
Laws of Inheritance
Law of Segregation: When gametes (sperm egg etc…) are formed each gamete will receive one allele or the other.
Law of independent assortment: Two or more alleles will separate independently of each other when gametes are formed
Mendelian Genetics
Gregor Mendel“Father of Genetics”
Augustinian Monk at Brno Monastery in Austria (now Czech Republic)
Not a great teacher but well trained in math, statistics, probability, physics, and interested in plants and heredity.
While assigned to teach, he was also assigned to tend the gardens and grow vegetables for the monks to eat.
Mountains with short, cool growing season meant pea (Pisum sativum) was an ideal crop plant.
Mendel worked with peas (Pisum sativum)• Good choice for environment of monastery• Network provided unusual varieties for testing• Obligate self-pollination reproductive system
Permits side-by-side genetic barriers
Cross-pollinations require intentional process• Crosses meticulously documented• Crosses numerically/statistically analyzed
TallP
Dwarfx
F1All Tall
Phenotype
One Example of Mendel’s Work
Clearly Tall is Inherited…What happened to Dwarf?
F1 x F1 = F2
F23/4 Tall1/4 Dwarf
Dwarf is not missing…just masked as “recessive” in a diploid state… there IS a female contribution.
Tall is dominant to Dwarf
TT tt
Tt
Genotype
HomozygousDominant
HomozygousRecessive
Heterozygous
Dwarftt
TallTt
t
TallTt
TallTT
T
tTPunnett Square:
possible
gametes
possible gametes
Unknown Tall Dwarfx
Mendel as a Scientist
tt
TallTt
TallTt
T
TallTt
TallTt
T
tt
possible
gametes
possible gametes
F1 x F1 = F2F2
Dwarftt
TallTt
t
Talltt
TallTT
T
tTPunnett Square:
possible
gametes
possible gametesTest Cross:
If Unknown is TT:
Dwarftt
Dwarftt
t
TallTt
TallTt
T
tt
possible
gametes
possible gametesIf Unknown is Tt:
Test Progeny All Tall
Test Progeny Half Tall Half Dwarf
1/3 of F2 Tall are TT2/3 of F2 Tall are Tt
GreenP
Yellowx
F1All Yellow
Phenotype
Another Example of Mendel’s Work
Clearly Yellow is Inherited…What happened to Green?
F1 x F1 = F2
F23/4 Yellow1/4 Green
Green is not missing…just masked as “recessive” in diploid state
1. Yellow is dominant to Green
2. Use G/g rather than Y/y for symbolic logic
gg GG
Gg
Genotype
HomozygousRecessive
HomozygousDominant
Heterozygous
Greengg
YellowGg
g
YellowGg
YellowGG
G
gGPunnett Square:
possible
gametes
possible gametes NEVER use G/Y or g/y
Unknown Yellow Greenx
Mendel as a Scientist
gg
YellowGg
YellowGg
G
YellowGg
YellowGg
G
gg
possible
gametes
possible gametes
F1 x F1 = F2F2
Greengg
YellowGg
g
YellowGg
YellowGG
G
gGPunnett Square:
possible
gametes
possible gametesTest Cross:
If Unknown is GG:
Greengg
Greengg
g
YellowGg
YellowGg
G
gg
possible
gametes
possible gametesIf Unknown is Gg:
Test Progeny All Yellow
Test Progeny Half Yellow Half Green
1/3 of F2 Yellow are GG2/3 of F2 Yellow are Gg
Mendel worked with peas (Pisum sativum)• Good choice for environment of monastery• Network provided unusual varieties for testing• Obligate self-pollination reproductive system
Permits side-by-side genetic barriers
Cross-pollinations require intentional process• Crosses meticulously documented• Crosses numerically/statistically analyzed• Scientists of 1860s could not understand math• Work lost in journals for 50 years!• Rediscovered in 1900s independently by 3 scientists• Recognized as landmark work!
Genetics After MendelRed
xYellow
All Orange
When these alleles go walking, they both do some talking (codominance)!
OK, so we cannot use R/r nor Y/y so we pick a third letter…P for the petal color gene.
Notice: we do NOT mix R/Y or r/y!
PRPR PYPY
PRPY
F1 x F1 = F2
F2
YellowPYPY
Orange
PRPY
PY
Orange
PRPY
RedPRPRPR
PYPRPunnett Square:
possible
gametes
possible gametes
P
F1
This F2 will NOT have a 3:1 ratio of phenotypes.
Instead it shows a 1:2:1 ratio!
The exception here proves the rule.
After 1900 several scientists tried to replicate Mendel’s crosses using other species including snapdragon.
In addition to this, there are multiple alleles possible:
PR = red PY = yellow p = no pigment
The combination of alleles in a diploid determine the flower color:
PRPR = redPRPY = orangePYPY = yellow
PRp = pinkPYp = creampp = white
Human hair color follows a similar pattern:
Alleles: HBn = brown HBd = blonde hR = red hbk = black
The combinations of these alleles determine the base hair color:
HBnHBn = dark brownHBnHBd = sandy brownHBnhR = auburnHBnhbk = dark brown
HBdHBd = blondeHBdhR = strawberry blondeHBdhbk = blonde
hRhR = redhRhbk = red
hbkhbk = black
Dominant does NOT mean frequent!Recessive can be common!
Another Example of Recessive Being Common: Pisum sativum
Garden Peas: green seed, wrinkled seed, dwarf stature, white flower
gg ww dd aa
In other words: a quadruple double-recessiveis the most common garden pea on Earth!
Quantitative Inheritance: multiple genes control trait
Highest Crop Yield: AABBCCDDEEIntermediate Crop Yield: AabbCCDdEe Lowest Crop Yield: aabbccddee
Darkest Skin Color: AABBCCDDEEIntermediate Skin Color: AaBbCcDdEe Lightest Skin Color: aabbccddee
AaBbCcDdEe x AaBbCcDdEe can produce a huge range of colors!
Phenotype = Genotype + EnvironmentCrop Yield = Genotype
+ Minerals + Water + Light - Pests
etc.
Human Skin Color = Genotype
+ Sun (UV) Exposure
- Aging Factors
The sun exposure effect is most obvious in people of intermediate skin base color
but everyone can have “tan lines.”
Optimizing these factors determines agricultural productivity…last part of our course!
Who Gets To Mate With Whom? …Two Extremes
Inbreeding Depression: related parents give same recessives to children
Hemophilia: Queen Victoria’s Mutation and Diseased Grandchildren
recessive sex-linked, X chromosome disorders, haemophilia is more likely to occur in males than females
Tay-Sachs: Jewish PopulationsRecessive autosomal disease; relentless deterioration of mental and physical abilities
Hybrid Vigor:
Wild Corn A x Wild Corn B
High Yield Hybrid Corn!
Tree method crossing of two traits(dihybrid)
Continuous Variation
Many traits may have a wide range of continuous values. Eg. Human height can vary considerably. There are not just "tall" or "short" humans
Gene interaction: Many biological pathways are governed by
multiple enzymes, involving multiple steps. If any one of these steps are altered. The end product of the pathway may be disrupted.
Environmental effects: Sometimes genes will not be fully expressed
owing to external factors. Example: Human height may not be fully expressed if individuals experience poor nutrition.
The Average American Phenotype
Ecosystems: Basic Concepts
What is an ecosystem?System = regularly
interacting and interdependent components forming a unified whole
Ecosystem = an ecological system;= a community and its physical environment treated together as a functional system
Ecosystem Services
The human economy depends upon the services performed for free by ecosystems.
The ecosystem services supplied annually are worth many trillions of dollars.
Economic development that destroys habitats and impairs services can create costs to humanity over the long term that may greatly exceed the short-term economic benefits of the development.
These costs are generally hidden from traditional economic accounting, but are nonetheless real and are usually borne by society at large. http://www.epa.gov/watertrain/pdf/issue2.pdf
Ecosystems:Fundamental Characteristics
Structure: Living (biotic) Nonliving (abiotic)
Process: Energy flow Cycling of matter (chemicals)
Change: Dynamic (not static) Succession, etc.
Abiotic components:
ABIOTIC components: Solar energy provides practically all the
energy for ecosystems. Inorganic substances, e.g., sulfur, boron,
tend to cycle through ecosystems. Organic compounds, such as proteins,
carbohydrates, lipids, and other complex molecules, form a link between biotic and abiotic components of the system.
BIOTIC components
The biotic components of an ecosystem can be classified according to their mode of energy acquisition.
In this type of classification, there are: Autotrophs and Heterotrophs Organisms that produce their own food
from an energy source, such as the sun, and inorganic compounds.
Organisms that consume other organisms as a food source.
Modified from: General Ecology, by David T. Krome
Trophic level: All the organisms that are the same number of food-chain steps from the primary source of energy
Trophic Levels
A trophic level is the position occupied by an organism in a food chain.
Trophic levels can be analyzed on an energy pyramid.
Producers are found at the base of the pyramid and compromise the first trophic level.
Primary consumers make up the second trophic level.
Secondary consumers make up the third trophic level.
Finally tertiary consumers make up the top trophic level.
Trophic Levels Found on an Energy Pyramid
The greatest amount of energy is found at the base of the pyramid.
The least amount of energy is found at top of the pyramid.
Source: corpuschristiisd.org/user_files/91702/Ecosystem.ppt
Food Chains
The producers, consumers, and decomposers of each ecosystem make up a food chain.
There are many food chains in an ecosystem.
Food chains show where energy is transferred and not who eats who.
Example of a Food Chain
Food Webs All the food chains in an area make up the food web of the
area.
Changes in Ecosystems:Ecological Succession
Definition:
Natural, gradual changes in the types of species that live in an area; can be primary or secondary
The gradual replacement of one plant community by another through natural processes over time
Primary Succession
Begins in a place without any soil Sides of volcanoes Landslides Flooding
Starts with the arrival of living things such as lichens that do not need soil to survive
Called PIONEER SPECIES
http://botit.botany.wisc.edu
http://www.saguaro-juniper.com/
Primary Succession
Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil
Primary Succession
Simple plants like mosses and ferns can grow in the new soil
http://uisstc.georgetown.edu
http://www.uncw.edu
Primary Succession
The simple plants die, adding more organic material
The soil layer thickens, and grasses, wildflowers, and other plants begin to take over
http://www.cwrl.utexas.edu
Primary Succession
These plants die, and they add more nutrients to the soil
Shrubs and tress can survive now
http://www.rowan.edu
Primary Succession
Insects, small birds, and mammals have begun to move in
What was once bare rock now supports a variety of life
http://p2-raw.greenpeace.org
Secondary Succession
Begins in a place that already has soil and was once the home of living organisms
Occurs faster and has different pioneer species than primary succession
Example: after forest fires
Climax Community
A stable group of plants and animals that is the end result of the succession process
Does not always mean big trees Grasses in prairies Cacti in deserts
Symmetry and Body Plan
SymmetryArrangement of parts with regard to
the axes and planes.Way a body parts is arranged around
a center point4 fundamental types of animal
symmetry: Spherical or universal Radial Biradial or radiobilateral Bilateral
Asymmetry
Anaxial symmetryBody cannot be divided by planes
into similar halvesBody is irregularly shapedNo definite anatomical relationship
between different parts
Asymmetry
Universal or Spherical
Homoaxial symmetrySymmetry exists in an organism that
can be dissected into equal or identical halves by any of the infinite axes and planes that transect it.
Assumes shape of ballBody parts arranged concentrically
around or radiating from a central point
Universal
Radial Symmetry
Monoaxial heteropolar symmetry Organism assumes shape of a cylinder
with parts arranged around and along a single central axis in which 2 ends are different: mouth and anus
Central axis is referred as longitudinal, oral-aboral or antero-posterior axis.
Plane passing through axis dividing organism into similar halves.
Radial Symmetry
Biradial symmetry
Dissymmetry
Bilateral Symmetry
only the transverse axis has similar ends.
Antero-posterior axis and dorso-ventral axis
Divides animal into right and left with mirror images
Bilateral Symmetry
Asymmetrical – without a balanced arrangement of similar parts on either side of a point or axis
Radial - any plane passing through the oral-aboral axis divides an organism to mirror images
Bilateral – only the midsagittal plane divides an organism to mirror images. Have definite anterior (head) and posterior (tail) ends
Other Features of animal Forms
Antimeres – identical and asymmetrically corresponding parts of an animal.
Arms of a starfish
Other Features of Animal FormsMetamerism – division
of body into segments or metameres. Segmentation may be
superficial or external (false) OR may include internal organs (true)
Segments may be similar (homonomous) OR different from each other (heternomous)
Other Features of Animal Forms
Cephalization – differentiation of anterior end of animal and is characterized by concentration of nervous elements such as formation of brain and sense organs.
Well-developed head region
Other Features of Animal Forms
Tagmatization or tagmosis – union of segments into larger functional groups. Each special group is a tagma (plural,
tagmata)
Animal Diversity
Why Things are Grouped
Put things in order Easier to find Show that things share certain traits
Methods of Classification Early Classification
Aristotle ▪ Plants and Animals▪ Plants (Green & Didn’t Move)▪ Animals (Weren’t Green & Move)
Aristotle’s Classification
Animals Land, Water, Air
Plants Size of plant Pattern of Growth
Aristotle’s Classification
Methods of Classification New Classification
Carolus Linnaeus (1735)▪ 2 main groups: Kingdom▪ Use specific traits into same group and called it species
▪ Placed similar species to larger group called genus
Linnaeus
Important Changes in Aristotle’s System:
1. Plants and Animals into more groups2. Based his system on specific traits3. Gave organisms names that described
their traits
- Living things had 2-part names:Genus species
Classification System
Classifying Organisms
Kingdom Phylum Class Order Family Genus Species
Comparing Classification groups and address informationCountry Kingdom
State Phylum
County Class
Town Order
Neighborhood Family
Street Genus
House number Species
Classification
How Scientists Classify Today
Look at Traits Compare traits of one organism with
those of another. Compare organisms living today
with those that lived long ago.
Classifying Based on How Organisms are Related
Classifying the House Cat
Other Evidence Used in Classifying Based on living thing’s ancestors
Horses and donkeys have many same ancestors
Similar body structures Human and cat have similar front limbs
and similar bones arranged in similar patterns
Body chemistry Horseshoe crab’s blood is similar to
spider
Scientific Name Comes from Classification
Why Scientific Names are Used
No mistakes can be made about which living thing is described.
Scientific names seldom change. Scientific names are written in
the same language around the world.
Kingdom Classification
AnimalPlantFungiProtistMonera
Modern Classification
Seven groups – Kingdom, phylum, class, order, family, genus, species
Evidence – Same ancestors, similar body structure, body chemistry
Organisms given 2-part scientific names
Kingdoms – Moneran, Protist, Fungus, Plant, Animal
Overview of Animal Diversity and Phylogeny
Diversified during Precambrian and Cambrian periods
Monophyletic Parazoans-first branch, lack true
tissues Radiata and bilateria two major
branches of Eumetazoa Evolution of body cavities Protostomes and deuterostomes
Parazoa
Sponges “beside the animals” Simple aquatic and marine forms
Eumetazoa
Two major branches: 1. Radiata-radial symmetry, top and
bottom, no front, back, or sides,
diploblastic larva 2. Bilateria-bilateral symmetry,
triploblastic, cephalization
Importance of Coelom
Acoelomates-no body cavity, Platyhelminthes
Pseudocoelomates-fluid filled body cavity, partially lined with mesoderm, Nematoda
Coelomates-fluid filled, completely lined with mesoderm, Annelida
Coelom-body cavity that protects internal organs
Protostomes and Deuterostomes
Protostomes: Mollusks,
Annelids, Arthropods
Spiral cleavage Determinate
cleavage Blastopore forms
the mouth schizocoelous
Deuterostomes: Echinoderms and
Chordates Radial cleavage Indeterminate
cleavage Blastopore forms
the anus Enterocoelous
The Origins of Animal Diversity
Colonial protist origin during Cambrian Explosion
Evidence from fossil beds: Burgess Shale, Yunnan region, Greenland
Why such rapid diversification?1. Adaptive radiation2. Predator-prey relationships3. Higher concentration of oxygen
Porifera - Sponges
No symmetryNo organsThe least complex animalsAquatic in fresh and marine
environments
central cavity
water out
water in
flagellummicrovilli nucleus
glasslike structural elementsamoeboid cell
poresemifluid matrixflattened surface cells
Body Plan of a Sponge
Venus’s flower basket (Euplectella)
Cnidaria
Radial symmetry Body has only 2 cell layers Mouth surrounded by tentacles with stinging cells Aquatic, FW and marine Include jellyfish, corals, sea anemones, hydra Some are motile, and all have a very simple
nervous system Respiration: direct gas exchange with aquatic
surroundings
outer epithelium (epidermis)
mesoglea(matrix)
inner epithelium
(gastrodermis)Medusa
Polyp
There are two Cnidarian body plans
reproductive polyp
female medusa male medusa
sperm
zygote
ovum
planulapolyp forming
branching
one branch from a mature colony
feeding
polyp
Life cycle of Obelia
Flatworms - Platyhelminthes Body has 3 cell layers: ectoderm, mesoderm and
endoderm Bilateral symmetry Parasitic and free -living aquatic (fw and marine)
and terrestrial: tapeworms, flukes, and Planaria Digestive system with one opening Primitive nervous system Hermaphroditic Respiration through skin
pharynx (protruded)
protonephridia
flame cell nucleus
cilia
fluid filters through membrane folds
flame cell
opening of tubule at body surface
Planaria, a free-living flatworm
brain nerve cord
genital pore
oviduct
testis
ovary
penis
a Larvae become encysted in intermediate host tissues
b A definitive host eats infected, undercooked beef
d Many proglottids form by budding
e Ripe proglottids containing fertilized eggs leave host in feces
f Cattle may ingest embryonated eggs or ripe proglottids to become intermediate hosts
c Scolex of larva attaches to intestine’s wall
Tapeworm life cycle
Roundworms - Nematoda Digestive system with mouth and anus
(“complete”) Separate sexes Aquatic and terrestrial, free living and
parasitic Body cavity gives “tube within a tube”
construction Respiration through skin, no circulatory
system
gonadpharynx intestine
false coelom
eggs in uterus anus
muscularized body wall
Caenorhabditis elegans
Body Plan of a Roundworm
Life cycle of Schistosoma japonicum
Mollusks - Mollusca
Often but not always have external shell Includes clams, oysters, snails, slugs,
squid, octopus, scallops, chambered nautilus
Body is soft with bilateral symmetry Nervous system, circulatory system,
respiratory system Some have excellent sense organs and
large brains, and can learn easily.
anus gillmantle cavity
radula
excretory organ
heart
stomach
shell
footmantle
digestive gland
Body Plan of a Snail
stomachkidneyesophagus
digestive gland
brain
arm
jaw
tentacle radula
siphon
anusink sac gill
heart accessory heart
reproductive organ
mantleintern
al shell
Body Plan of a Cuttlefish
Segmented Worms - Annelida Body composed of many identical
segments. Allows more specialization Aquatic or terrestrial Includes clam worm, feather worms,
leeches, and earthworm. These animals have “all” systems, and are
quite complex. They are most likely the ancestors of the Arthropods, the most successful Phylum of animals on Earth.
“jaws”
toothlike structurespharynx (everted)
antenna
palp (food handling)tentacle
eyes
chemical-sensing pit
parapod
• Taxonomy is the science of grouping
and naming organisms.
• Classification the grouping of information or objects based on similarities.• The scientific name comes from one of two
“dead” languages – Latin or ancient Greek.
• a two name system for writing scientific names.
• The genus name is written first (always Capitalized).
• The species name is written second (never capitalized).
• Both words are italicized if typed or underlined if hand
written.
Example: Felis concolor or F. concolor
Which is the genus? The species?
Binomial Nomenclature
"Formal" scientific names should have a third part, the authority. The authority is not italicized or underlined.
The authority is written as an abbreviation of the last name of the person responsible for naming the organism. Since Carolus Linnaeus was the first person to name many plants, the L. for Linnaeus is very common in plant scientific names.
An example is Quercus alba L.