Transcript The Worms - KCI-SBI3U

General characteristics
•Eukaryotic
•Multicellular
• Heterotrophic
•No cell wall
•usually mobile in at least
one stage of their life
•produce sexually and
produce an embryo
Level of Organization
Cells  Tissue  Organs  Organ systems  Animal
General Characteristics
2. Types of tissues
Tissue
except Phylum Cnidariano mesoderm
Gives rise to…
Location
ectoderm
epidermis and nervous
system
outer layer
mesoderm
circulatory,
respiratory and
skeletal systems
middle layer
endoderm
Digestive tract
inner-most layer
Characteristics
Symmetry and body plan
• Asymmetrical body plan: irregular body
shape
• Radial symmetry:
- can be divided into equal halves by a
plane passing through the central axis
in any direction
• Bilateral symmetry:
- body can be divided into equal halves
only along a single plane
- organisms with bilateral symmetry
exhibit cephalization
Our body symmetry?
Radial? symm.
Cephalization
• concentration of sensory organs
and nerve cells at the anterior end
• acts as a control centre
• allows organism to respond to
stimuli quickly
• evolutionary favoured
General Characteristics
Presence of a Body Cavity
• Coelom: fluid-filled body cavity
with organs suspended inside
• Developed from mesoderm
• Presence of compartments also
means nutrients and O2 may not
be diffused to every cells
• Coelomates: animals with a
coelom.
• Acoelomates: animals without a
coelom (e.g. corals, jelly fish and
flatworms)
Advantages of a Coelom
• acts as a cushion for
internal organs
• provides more room for
internal organs to expand
• allows animal to become
larger
• allows digestive tract to
develop specialized
regions and formation of
blood vessels
General Characteristics
Segmentation
• The division of the body into repetitive sections
e.g. worms and scorpions
• A single segment can be damaged, but the other
segments can continue to function properly
• Mobility is more effective because segments
move independently
Movement
• Complex and fast movement
• Some are sessile (stationary) as adults e.g. sponges
and sea anemones. They live attached to one place
such as the bottom of the ocean or a rock.
• Sessile animals have a body form that can move
during juvenile stages of development
Recall
• Zygote: cell formed after an egg is fertilized by a
sperm
• Gametes: sex cells like eggs and sperms
• Diploid: containing two copies of each
chromosome (2n)
• E.g. A human zygote contains 46 chromosomes
• Haploid: containing half the usual # of
chromosomes (n)
• E.g. Human eggs and sperms are gametes each
contains ? chromosomes
General Characteristics
Master of Cloning: https://www.youtube.com/watch?v=J7eRGHVx3p0
Reproduction
• Sexually reproduction using gametes (haploid eggs and sperm meet to form a
diploid zygote)
• Internal (inside female body) or external (in aquatic environment) fertilization
• Some animals switch between asexual and sexual modes, reserving sexual
reproduction for when the conditions are tough
Duck+ beaver + otter = platypus
With shelled egg- bird, platypus
Live birth- aphid, whale
Animal Evolution
Cnidaria
Porifera
sponges
jellyfish
Nematoda
Platyhelminthes
Annelida
Mollusca
flatworms roundworms mollusks
Echinoderm
Arthropoda
segmented
worms
insects
spiders
Chordata
starfish
vertebrates
backbone
segmentation
endoskeleton
coelom
body cavity
bilateral symmetry
tissues
multicellularity
Ancestral Protist
Part II- Diversity in Animal Kingdom
Animal Diversity
Porifera (sponges)
Cnidaria
Porifera
Sessile but living
Cnidaria
Animal Diversity
Platyhelminthes
(flat worm)
Nematoda (round worms)
Annelida (segmented)
Platyhelminthes
ectoderm
mesoderm
endoderm
Planaria regeneration
http://www.youtube.com/watch?v=vXN_5SPBPtM
Symmetry and cephalization observed in Planaria
http://www.youtube.com/watch?v=w0QzSYQGsnA
C. elegans
Nematoda
•
•
Roundworm:
http://www.youtube.com/watch?v=DxL2qHBetvI
Guinea worm:
http://www.youtube.com/watch?v=nu3z7mRyLRc
Nematoda
- Loa loa is a filarial nematode
(roundworm) species
- Lives in human eyes“eyeworm”
- Hosts can feel the worm
moving in the eye and can see
it floating in there if it’s big
enough.
- easily killed using antibiotics or
is extracted through minor
surgery, though it can live
inside a human for up to 17
years.
http://www.liveleak.com/view?i=67a_1341408640&comments=1&use_old_player=0
Annelida- segmented worm
fan worm
leech
Animal Diversity
mollusca
echinodermata
Mollusks
http://www.ted.com/talks/david_gallo_shows_underwater_astonishments.html
Animal Diversity
crustaceans
arachnida
insecta
Diploda / chilopoda
Insecta
• Most successful invertebrate
• Parasites hijack host behaviour
the case of parasitic wasp and catepillar
http://www.youtube.com/watch?v=vMGLWyNcAs
Echinoderms
Animal Diversity
Tunicates +
lancelets
jawless fish
cartilage fish
bony fish
amphibians
reptilia
aves
mammalia
Tunicates and
Lancelets
Sea Lamprey- jawless fish
Parasitic eel-like creatures with suction-cup, bloodsucking mouths.
Also an invasive species to the Great Lake ecosystem
Rays always look so cheerful!
Bony fish
Amphibians
Gastric brooding frogs- now extinct
Disappearing of Frog
http://www.youtube.com/watch?v=ZWHibAQ0Sso
http://animal.discovery.com/tv-shows/other/videos/the-vanishing-frogwith-jeff-corwin.htm
1. What proportion of amphibians are in trouble?
- 30%
2. How long have amphibians been around?
- 300 million years
3. What is the disease mentioned in the video that kills off amphibians?
What is the cause of such disease?
Chytrid disease caused by chytrid- an aquatic fungus that attacks frog’s
skin.
4. What strategies have been done to increase frog number?
Treatment of frogs with antifungal drugs; captive breeding
5. Why should we be worried about frog’s disappearing?
- their dual habitats (i.e. land and water) make them good indicators of
healthy ecosystem; humans benefit from frog’s chemical; they are
the link b/t terrestrial and aquatic food web
Birds- known for their feathers and
…. Attitudes :
Archaeopteryx
Fossil record indicates birds and reptiles are
closely related
Mamalian
14 panda babies artificially bred in China
http://www.bbc.co.uk/news/world-asia-china-24223721
The Worms
Platyhelmint
Nematoda Annelida
hes
Commo
n Name
Flatworm
roundworm
Segmented
worm
The Worms
Platyhel
Nematoda Annelida
minthes
Type of
symme
try
bilateral
bilateral
bilateral
The Worms
Platyhel
Nematoda Annelida
minthes
Type of
body
cavity
none
pseudocoelom Coelom
(body cavity
(fluid filled
partially lined
space
with
completely
mesoderm)
lined with
mesoderm
Body
Cavity
ectoderm
mesoderm
endoderm
acoelomate
ectoderm
mesoderm
endoderm
pseudocoelomate
pseudocoelom
ectoderm
mesoderm
coelom cavity
coelomate
endoderm
The Worms
Platyhe
lminthe Nematoda Annelida
s
# and
Name of
Cell
Layers
3–
3 – ectoderm, ectoderm,
3–
ectoderm, mesoderm and mesoderm
and
mesoderm endoderm
endoderm
and
endoderm
The Worms
Platyhelminthes Nematoda Annelida
Cephali
zation?
yes
yes
yes
The Worms
Platyhelm
Nematoda Annelida
inthes
Digesti
ve
Syste
m
One digestive
opening
Separate
(food and Separate anus anus and
wastes
mouth
and mouth
through the
same
opening
The Worms
Platyhelm
Nematoda Annelida
inthes
Circ
and
resp.
syste
ms
Simple
diffusion
through gas
exchange
Yes – due to
large size
The Worms
Platyhelm
Nematoda Annelida
inthes
Misc.
Featur
es
Exhibit 2
forms of
lifestyles:
free-living
and parasitic
e.g.
tapeworms
Thin body wall
and round
shape
minimize
minimize outer
surface area
The Worms
Annelida
Misc.
Featur
es
Segments are identical - can
increase in size without losing
the capacity to transport
materials and relay messages
– segmentation improves
movement / flexibility
Our evolutionary cousin
http://youtu.be/G32YehcdUAw
Extra material
Classification
1. Invertebrates
• Animals without backbones
• Occupy almost all terrestrial and
aquatic ecosystems
• Have existed for hundreds of
millions of years
2. Vertebrates
• Phylum Chordata
• Have a skull and a backbone that
protects the nervous system
(brain and spinal cord)
Invertebrates
1. Sponges and Cnidarians
Sponges (Phylum Porifera)
• Found in marine and freshwater
environments
• Have asymmetrical body plan and no
tissues
• Body consists of 2 layers of independent
cells that can be separated into clumps of
cells  able to reassemble themselves
into a whole sponge again
• Sessile adults  feed by trapping food
particles in water passing through their
bodies
Invertebrates
1. Sponges and Cnidarians
Cnidarians (Phylum Cnidaria) e.g. corals, sea anemones, hydras
• Have two layers of cells and tissues including muscle tissues  able to
swim and capture food using stinging tentacles around their mouth.
• Have radial body symmetry and two body forms
• Polyp: a cylindrical form that attaches to a surface, extending
tentacles upward and downward
• Medusa: a flattened, mouth-down form that is not attached. They
move passively with currents or actively by body contractions e.g.
jellyfish
Invertebrates
2. Worms
• Flatworms are acoelomates with three layers of cells
• Have simple nervous system with a brain-like concentration of cells,
including an eyespot, at the head end.
• Segmented worms are coelomates
Invertebrates
3. Molluscs
• 3 classes: bivalves (clams), gastropods (snails) and cephalopods (octopus)
• Second most diverse animal phylum
• Bilateral symmetry with 3 layers of cells, a coelom and two body openings
• Have a soft body that is protected by a hard shell and a mantle that
surrounds the internal organs and secretes CaCO3 for the shell
• Contain various organs, eyes, sense organs and a muscular foot for
movement
Invertebrates
4. Echinoderms
• Sea stars, sea urchins, sea
cucumber…
• Radial symmetry, spiny
endo-skeletons (an internal
skeleton that protects
organs and provides support
for muscle attachment.
• Have tube feet: small
muscular, fluid filled tubes
that are similar to suction
cups
Invertebrates
5. Anthropods
• Arthropod means jointed foot  legs are made up of movable
sections connected to joints
• Segmented bodies and a hard exoskeleton (protein + chitin) that
protects the internal organs.
• Chelicerates: Spiders, scorpions, mites
• Mayriapods: centipedes and millipedes
• Insects: beetles, bees, butterflies, ants…
• Crustaceans: crabs, lobsters, shrimps…
Vertebrates
Tetrapods
Embryo in a fluid-filled sac
Vertebrates
1. Fish
• Lampreys are the oldest living vertebrates
• Have gills to obtain dissolved oxygen from water (rely on a
suction mouth for holding on to food)
• Advanced animals have jaws, fins and bony skeleton
• Swim bladders: air sacs that allow a fish to sink or rise in
water
Vertebrates
2. Amphibians
• E.g. frogs, toads and salamanders
• Have moist skin to assist in gas exchange in addition to lungs
• External fertilization
Vertebrates
3. Reptiles
• 3 orders remain: Squamata (lizards
and snakes), Testudines (turtles), and
Crocodilia (crocodiles)
• Use only lungs for gas exchange
• Ectothermic: have a 3 chambered
heart  relies on environmental heat
for determining internal body
temperature
• Internal fertilization (amniotic egg) 
outside incubation of shelled egg.
Vertebrates
4. Birds
• Endothermic: have a 4-chambered heart that use internal metabolic
heat to maintain a high, constant body temperature
• Most can fly
• Bones are lightweight and hollow, and bodies are compact  keep
body weight low
Vertebrates
5. Mammals
• Distinct features: mammary glands (milk production) and a highly
developed brains
• Hair: defence (porcupine), sensory detection (eyelashes)
• They are endothermic
5a. Monotremes
• Egg-laying mammals
• Only living example: duck-billed platyus and echidna in Australia
and New Guinea
Vertebrates
5b. Marsupials
• Pouched mammals
• Have a short gestation period
• Mostly found in Australia
• E.g. koala bears and kangaroos
5c. Placental Mammals
• Have placenta
• Have great diversity in species and structure
• E.g. bats, bears, whales, primates and humans
Our evolutionary cousin
http://youtu.be/G32YehcdUAw