Porifera,
Cnidaria,
and
Flatworms
Levels of Organization
• All animals are multicellular – made of more
than 1 cell
• Animals can be organized on the cellular,
tissue, or organ level of organization.
• Cell – Sponge
• Tissue – Jellyfish
- Have endoderm & ectoderm only
• Organ – Worms
- Have ectoderm, endoderm, and
mesoderm
Type of Body Plan
• Two body plans are present in the animal
kingdom:
• Sac plan:
• Incomplete digestive system with only one
opening.
• Ex: Jellyfish
• & planaria
•Tube-within-a-tube plan:
•Complete digestive system.
•Two openings allows for specialization
along the length of the tube.
•Ex: Roundworms, earthworms, insects
Type of Symmetry
• Three types:
• Asymmetrical animals have no particular
symmetry.
• Radial symmetry means the animal is
organized similar to a wheel.
• Bilateral symmetry means the animal has
definite right and left halves.
Type of Coelom
• Coelom - an internal body cavity where internal
organs are found.
• Ex: Mollusks, annelids, echinoderms,
vertebrates
• Pseudocoelom - a body cavity incompletely
lined with mesoderm.
• Ex: Roundworms, rotifers
• Acoelomates - have mesoderm but no body
cavity.
• Ex: Flatworms, sponges, jellyfish
Segmentation
• Segmentation is the repetition of body parts
along the length of the body.
• Animals can be segmented or nonsegmented.
• Segmentation leads to specialization of parts.
• Ex: annelids, arthropods, and chordates
(includes vertebrates).
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•
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Phylum Porifera - Sponges
Meaning: Pore-bearing
Symmetry – none (asymmetrical)
Organization – cellular level
Acoelomates – no body cavity (so no
organs)
Non-segmented
Habitat – fresh & salt water
• Anatomy (see below and on next slide)
Osculum
Amebocyte
Collar cell
Flagella
Pore channel
Pores
Spicules
Epidermis
Internal
cavity
Filaments
Flagella
Collar cell
Anatomy
•Epidermis – found along outer body wall
•Amoeboid cells (amebocytes) – middle layer
•Transport nutrients
•Produce spicules
•Form sex cells
•Collar cells - inner layer – digest nutrients
•Collar cells contain the following:
•Flagella - pull water in through pores and
circulate water though the sponge
•Filaments - trap food particles.
•
•
•
•
Life processes
Sponges are classified according to type of
spicules
Support - spicules (act like bones for the
sponge)
Diet - filter feeders – filter bacteria,
protists, and sometimes small crustaceans
Feeding –
– Filaments trap food
– Collar cells digest food
•Movement:
- Swim as larva
- Sessile (permanently attached to a
surface) as adults.
•Response - no nervous system.
•Excretion - through the osculum.
•Respiration - take in oxygen as water passes
through body – diffusion.
•Reproduction –
•Hermaphrodites (make eggs & sperm).
•Asexually by:
•Budding: Produce internal buds that
can grow into new sponges when the
conditions are more favorable
•Regeneration: Growth of a whole
organism from a fragment
•Sexually:
•Release sperm into the water
•Sperm enters pores of another sponge of
same species
•Fertilizes egg within
•Larva released through osculum
•(see life cycle diagram next slide).
•Poor reproductive odds!!!
http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Q-sponge.htm
5.
1.
2.
1. Sperm
2. Egg
3. Dividing cells
(spongocoel)
4. Larva
5. Larva released
6. Flagella (moves)
7. New sponge develops
6.
3.
7.
4.
Phylum Cnidaria
•Named for – specialized stinging cells called
cnidocytes (contain the stingers called
nematocysts – these may contain poison)
•Symmetry – radial
•Organization – tissue level
•Acoelomates – no body cavity (so no organs)
•Non-segmented; sac body plan
•Habitat – mostly salt water, hydra found in fresh
water
•Body forms: may be a polyp or a medusa, or
may alternate between the two forms.
•Polyp – tentacles up, usually sessile
•Medusa – tentacles down, usually active
•Examples of animals –
•Sea anemone – solitary polyp, very colorful
•Coral – some solitary, most colonial, polyp
form, calcium carbonate skeleton, form reefs
•Portuguese man-of-war – colony of polyp &
medusa individuals, each with specialized
jobs such as feeding & reproduction
•Jellyfish – medusa, can live at great depths
•Hydra – freshwater, polyp form, commonly
attached to underwater rocks or plants, less
than 1cm in length
Tentacle
Mouth
Ectoderm----
Ovary
Stinging capsule
-------Endoderm
------------------------GVC
– Gastrovascular cavity
Bud
Testis
Sperm
Developing egg
Basal disc
Anatomy
•Sac body plan – single opening serves as mouth
and anus
•Outer tissue layer – ectoderm
•Inner tissue layer – endoderm
•Mesoglea – jelly-like material that separates
above 2 tissue layers
•Muscle fibers running in 2 directions
•Tentacles surround mouth
•Large space inside called gastrovascular cavity
(GVC)
Life processes
•Movement:
•Directional
•Move by contraction & expansion of
body
•Tentacles can grab prey
•Response:
•Nerve net – interconnecting nerve cells
and communicate with sensory cells
throughout body (think of a basketball
net)
•Support
•Hydrostatic skeleton –fluid-filled closed
chambers
•Diet – protists and small animals
•Feeding –
•Sting prey with nematocysts (stingers)
•Stuff food into mouth using tentacles
•Don’t chase their prey – but movement of
medusa can help drawn food in towards
body.
•Food passes into GVC (gastrovascular
cavity)
•Digestion – by cells of endoderm
•Internal transport:
•Nutrients and oxygen pass from cell to
cell through the process of diffusion
•Respiration:
•Diffusion between ectoderm & water.
•Excretion:
•Wastes are excreted through the mouth
•Reproduction:
•Usually appear as separate males & females
•Sexual reproduction – see life cycle diagram
given separately
•Jellyfish –
•Release eggs & sperm into water
•Swim as larva, settle as polyps, then
divide to become medusa
•Several young from one fertilized egg
•Hydra – release egg or sperm from body
wall; meet, swim as larva, settle as polyp
Medusa
Egg
Blastula
Planula
Polyp
Sperm
•Asexual reproduction
•Budding – cluster of cells form, break off ,
grow into adults
•Regeneration – fragments develop into new
animals
Phylum Platyhelminthes
•Meaning – flatworms
•Symmetry - bilateral
•Sac body plan
•Non-segmented
•Acoelomates
•Organization – organ level
•Have organs for all life processes except
respiration and circulation
•Habitat – fresh or salt water, moist environments,
inside host
•Examples:
Tapeworms
Marine flatworms
Flukes
Freshwater planarians
Planarians • Lifestyle - free-living
• Habitat - freshwater
• Movement – secrete slime, push through with
cilia, muscles
• Excretion – flame cells – interconnecting canals
throughout body
• Response - small brain
- ladder of nerves
- light-sensitive eyespots
- Auricles sensitive to chemicals
• Respiration - diffusion
•Internal transport - diffusion
•Diet – plankton (small worms or crustaceans)
•Feeding – wrap around prey
- secrete slime
- extend pharynx to suck up food
•Digestion – occurs in GVC
•Gender - hermaphrodites
•Sexual reproduction – have sex, exchange sperm,
each planaria gets pregnant - 2 sets of young hatch
from eggs 2-3 weeks later.
•Asexual reproduction – capable of regeneration;
1 worm can even grow 2 heads or 2 tails!!
Planarian
Eyespot
Brain
Auricle
Longitudinal
nerve cord
Transverse
nerve cord
GVC
Pharynx
Flame
cells
Excretory pore
Mouth
Mesoderm
Endoderm
Ectoderm
GVC
Flame
cells
Cilia
Ovary
Oviduct
Testes
Sperm
duct
Penis
Vagina
Parasitic Flatworms
• Two classes - flukes and tapeworms
• Require host to carry on life cycle – see next slide
• Primary host – infect as adult
• Secondary host – infect as larval stage
• Tapeworm –
• Scolex with hooks and suckers to hold itself
inside the gut.
• No digestive system; absorbs host’s digested
food through skin
•Body is an assembly line of square sections
called proglottids, which contain male and
female sex organs.
•As proglottids mature, they break off, pass
with feces, and release eggs.
•When animals feed in feces-contaminated
food, larva eventually form cysts in muscles of
secondary host.
•When humans eat infected meat, larva hatch
from cyst, attach to intestine, and grow to
adulthood.
1. Hooks
2. Suckers
3. Scolex
4. Neck
5. Proglottids
6. Testes
7. Ovary
8. Eggs
9. Detached proglottid
10. Longitudinal nerve cord
11. Brain (ganglia)
12. Transverse nerve cord
Life cycle:
•Contracted by eating undercooked, infected
beef, pork, or fish.
•Transmitted to cats & dogs by fleas that have
eaten feces of infected host
•Primary symptom – weight loss
•In prolonged infections – worms migrate to
eyes, heart, brain, lungs, & liver & form cysts –
cause swelling, cramps, diarrhea, anemia, &
seizures
•Diagnosed by fecal exam; treated with medicine
Fluke
•Have sucker at anterior end to attach to host
•Various species – can infect digestive tract, bile
duct, blood, & lungs.
•Blood flukes cause schistosomiasis – one of the
most common worm infections worldwide
(about 200 million in mostly Middle East, Asia,
Africa, & S. America)
•Common in areas with poor sewage treatment
•Enter through skin when in infected water – see
life cycle diagram next slide
Schistosomiasis
•Diagosed by fecal exam; treated with
medicine
•Symptoms: nausea, abdominal pain,
increased bowel movements, diarrhea, weight
loss, fatigue
•Burrow through host, feed on host’s blood &
tissues.
•Can live for up to 2-3 decades inside host
(usually only 5-10 years)
•Reproduce non-stop – 100 – 300 eggs/day