Transcript Cnidarians - carverbiology11

Review of
the Animal Kingdom
Identify and define the two major
divisions of the Animal Kingdom:
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Invertebrates – animals that lack a
backbone
Vertebrates – animals that have a
backbone
List four general characteristics of the
Kingdom Animalia:
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Multicellular
Eukaryotic
Heterotrophic
Cells lack cell walls
Name and describe four evolutionary
trends in the Kingdom Animalia:
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1) cell specialization and levels of
organization – specialized cells, tissues,
early development
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2) body symmetry – asymmetry, radial,
bilateral symmetry
3) cephalization – concentration of
sense organs at the anterior of body
4) body cavity formation – fluid-filled
space for internal organs
List and define seven essential
functions in animals:
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1)
2)
3)
4)
5)
6)
7)
feeding
respiration
circulation
excretion
response
movement
reproduction
The Sponges – Phylum Porifera
Porifera – the sponges
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Porus (pore) + Fera (bearing) Abundant
marine group with some fresh water (f.w.)
species. Can range in size from small crusts
or growths or simple vases few mm high to
1-2 meters.
Sponges are multicellular, heterotrophic,
have no cell walls, and contain a few
specialized cells
Classification
Kingdom Animalia (animals)
Phylum Porifera (sponges)
Classes:
1. Calcarea (calcerous sponges - having spicules)
2. Demosponginae (horn sponges, like the bath
sponge)
3. Scleropongiae (coralline or tropical reef sponges)
4. Hexactinellida (glass sponges).
Definition
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2.
3.
Porifera are asymmetrical or radially
symmetrical animals without
Organs, mouth, digestive system or
nervous tissue.
Their bodies are porous, with canals and
chambers through which a water current
flows,
One to many internal cavities lined with
choanocytes.
Symmetry Explained
Bilateral Symmetry - Right side of body is mirror image of the left
side
Radial Symmetry - One slide (like pie) is the mirror image of
another slice.
ASymmetry
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Asymmetry. No slice through the body will
divide it into two like halves. Most sponges.
Asymmetrical animals are plant-like and
display irregular growth.
Radial Symmetry
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Radial symmetry. The body has the general
form of a short or tall cylinder with one main
longitudinal axis around and along which
parts are arranged.
Any plane through this longitudinal axis
divides the body into 2 like halves.
Examples: Some of the sponges which are
vase-shaped, the Cnidaria and the
echinoderms.
Bilateral Symmetry
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Bilateral symmetry.
one plane of symmetry
which divides an animal
into left and right
halves which are
comparatively the
same.
Most animals.
More Defining Characters
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No mouth organs, systems, digestive
tract, anus, nerve cells.
Surface perforated by numerous pores.
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Incurrent openings are small and
numerous
Excurrent - few and large
More Defining Characters
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Internal cavities.
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Interior is hollow or permeated by
numerous channels.
Some or all interior spaces are lined by
specialized cells called choanocytes.
Sponge Anatomy 101
Feeding
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Sponges are filter feeders that sift
microscopic food particles from the
water
Digestion is intracellular (takes place
inside cells)
Choanocytes trap and engulf food from
water passing through the sponge, then
archaeocytes complete the digestive
process
Respiration, Circulation, and
Excretion
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Sponges rely on water being passed
through its body cavity for respiration,
circulation, and excretion
Oxygen from the water diffuses into the
cells of the sponge body, and ammonia
and other wastes diffuse from the body
into the water
Response
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Sponges don’t have nervous systems
They can produce toxins to protect
them from potential predators
Reproduction
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Sponges can reproduce asexually and
sexually
Sexual reproduction:
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A single sponge produces egg and sperm, each
released at different times
Eggs produced by one sponge is carried through
the water to another sponge and fertilized in the
sponge’s body  internal fertilization
Fertilization  zygote  larva (immature stage)
Sponge Reproduction…
Reproduction (cont’d)
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Asexual reproduction:
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Sponges can reproduce asexually by:
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Budding – part of sponge breaks off of the
parent and grows into a new sponge on the
sea floor
Sponges can produce gemmules – groups of
archeocytes surrounded by spicules; gemmules
can survive harsh conditions and grow into a
new sponge in favorable conditions
Cool Stuff – Regeneration!
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Tremendous ability to repair and restore
lost parts.
Can also reconstitute selves if totally
disintegrated.
Sponge tissue has some similarity to
human connective tissue. Could lead to
aid in tissue transplantation.
Importance of Sponges
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4.
Reefs provide habitat for many animals
Vacuums of the sea -- clean up the sea
floor/oceans
Sponges are a commercial venture
Several medicinal compounds, including
antibiotics, antivirual drugs, and drugs for
leukemia come from sponges.
Cnidarians
Jellyfish, Corals Anemones
and Hydroids
Cnidarians eat mussels,
fish, plankton, and worms.
Cnidarians eat by
stinging their prey so it
becomes paralyzed,
and then they bring the
food into their
stomach.
Phylum Cnidaria
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2.
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Soft bodied animals with stinging tentacles
arranged in circles around the mouth
Radial Symmetry
Specialized cells and tissues, including nervous sys
Lifecycles often include two different stages:
polyp and medusa
3 Body layers: Ectoderm, Mesoderm, Endoderm
Nematocysts – stingers
Only one internal cavity, the digestive cavity, with
a mouth, but no anus.
Cnidarians
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Definition:
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Cnidarians are soft-bodied, carnivorous
animals that have stinging tentacles
arranged in circles around their mouths
Have body symmetry and specialized
tissues
Name comes from cnidocytes, or stinging
cells, found in their tentacles.
Body Plan
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Cnidarians are radially symmetrical
Have a life cycle that includes 2
different—looking stages: a polyp and
a medusa
Life Cycle & Polymorphism
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Two basic types
of individuals:
polyps and
medusae.
Dominance of
Medusa or Polyp
lifecycle varies
species to
species.
Polyp Stage of Life Cycle
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Polyp = adapted
for sedentary or
sessile life.
Tubular body w/
mouth at one
end surrounded
by tentacles.
May live singly or
in colonies.
Colonial polyps
Medusa
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Medusa = jellyfish form, free swimming and sexually
mature form,
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bell-shaped or umbrella-shaped bodies,
radial symmetry
mouth centered on concave side, tentacles and one or more
types of sense organs borne on rim of umbrella.
Medusa provides dispersal mechanism so don't
compete with parents. Mesoglea much thicker than in
polyp - constitutes bulk of animal - makes it buoyant
= "jelly" of jellyfish.
Medusa
CNIDARIANS have no
bones, are hollow with 3
layers of cells.
They live in salt or fresh
water.
When a cnidarian
reproduces, the young hatch
into the mother stomach,
then, She spits them out.
Feeding
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Inside the cnidocytes of the tentacles are
nematocysts, poison-filled stinging
structure with a dart, that can sense prey,
then release the dart into the prey,
paralyzing/killing them
Prey is then taken into the cnidarian’s
gastrovascular cavity, a digestive
chamber with one opening
Digestion is extracellular (takes place
outside of cells)
Nematocysts
1. Hold prey
2. Sticky -- aid in locomotion by attaching tentacles
3. Penetrate and anchor in prey and poison it.
Nematocysts video:
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Nematocysts firing:
http://www.youtube.com/watch?v=6zJi
Bc_N1Zk&feature=related
Nematocysts can be Pretty
Nematocyst poison
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Most dangerous to man is Cubozoan jellyfish, the sea
wasp (Chironex fleckeri). Caused more human
suffering and death off Australian coasts than
Physalia (Portuguese man-of-war) has in any of its
home waters.
Symptoms range from:
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burning pain at site of contact
lesions and eruptions of various sorts, often severe
enough to leave scars,
great pain, fever, and respiratory interference.
severe reactions due to shock & allergies
"Sting" of most is imperceptible to humans.
Problems usually occur only when repeatedly stung.
Respiration, Circulation, and
Excretion
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Nutrients transported throughout body
by diffusion
Respiration and excretion also by
diffusion through body walls
Response
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Cnidarians have specialized sensory cells
Nerve net – a loosely organized network of
nerve cells that allow the organism to detect
stimuli
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Nerve net usually distributed evenly throughout
the body, but in some cases are concentrated
around the mouth or in rings
Statocysts – sensory cells that determine
direction of gravity
Ocelli, or eyespots, that detect light
Movement
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Different ways of moving
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Hydrostatic skeleton – circular and
longitudinal muscles (sea anemones)
Jet propulsion – muscles contract, pushing
water out and the organism forward
(medusas)
Reproduction
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Asexual – budding
Sexual
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External fertilization – female cnidarian
releases eggs into water, male cnidarian
releases sperm  fertilization in water 
zygote  free-swimming larva  polyp 
medusa
Video:
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Sea anemone reproduction
http://www.youtube.com/watch?v=u8L
GZaezpV8&feature=related
Classification of Cnidarians
Classes: Scyphozoa, Cubozoa and
Anthozoa
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Jellyfishes (Classes Scyphozoa and Cubozoa)
are predominantly medusae w/ polyp stage
very reduced or completely absent.
Corals and anemones (Class Anthozoa) are
entirely polyps, no medusa.
The Portuguese Man o War
wasn’t just a Ship
Physalia from Jamaica
Portugues
e Man O
War
A tenacious
hunter with a
taste for fish
and the
poison to
render most
prey helpless
Yikes!
Portuguese Man 'O War
Physalia physalia
Size: to 1 ft (float) and 50 ft (tentacles)
Habitat: floats at the surface
Notes: dangerous
Fortunately, this creature, with its powerful battery of stinging
tentacles, is more common in bays and protected waters than in the
open ocean. The sting of the Man'O'War can vary from extremely
painful to incapacitating to fatal, depending on the severity and the
victim's reaction.
Jellyfish sting to defend themselves.
The Man of War is poisonous to humans.
When a cnidarian
reproduces, the
young hatch into
the mother’s
stomach, then, she
spits them out
Other Dangerous Jellyfish
Moon Jellyfish / Red Jellyfish ( Lion's Mane )
Aurelia aurita / Cyanea capillata
anywhere
Notes:
Jellyfishes are free-swimming relatives of corals,
anemones, and hydroids. In fact, in many cases they are
the same animal, just in a different stage of life ! Not all
medusas ( as jellyfishes are called ) have a
corresponding polyp stage, and likewise not all polyps
have a corresponding medusa stage, but most conform
to this life cycle. Small jellies ( up to 1" across ) are most
likely the medusa stage of some hydroid, while large
jellies are usually the dominant stage of a species in
which the polyp stage is almost absent.
Translucent Moon Jellies are harmless and quite
common. Red Jellies have a painful wasp-like sting, but
are usually much less common. And try as you might to
avoid it, sooner or later every northern diver will get a
stray tentacle draped across the face and lips - the only
places exposed to attack.
Habitat:
Moon Jellyfish
Beached Moon Jellies: the surf has stripped away all the tentacles,
leaving just a harmless dying blob of goo.
Red or
Lion's Mane
Jelly
Avoid these.
Swim away
– swim away
NOW! !
Clown fish live in
anemones, and coral
and they’re immune to
stings!
Fire Coral and Tube Anemone
Videos!
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Jellyfish:
http://www.youtube.com/watch?v=Hqf
Cm58SB6Y
http://www.youtube.com/watch?v=pCV
ADKwqwnc