Transcript Class Anthozoa

What is Cnidarian?
• Marine Invertebrates
• 9,000 species
• Jellyfish, Coral, Sea
Anemones, Hydras
• Found Worldwide
Cnidarian Characteristics
• Radial Symmetry
– Arranged in
circular pattern
• One body opening
– Mouth & anus
• Simple nervous
system
• Stinging cells
Cnidarian Body Forms
• Polyp
– Tube-shaped body with
a mouth surrounded by
tentacles
• Medusa
– Umbrella shaped with
tentacles hanging down
Polyp-Forms
• Hard Corals
• Hydra
Sea anemones
Skunk Anemonefish
Bulb Tentacle Sea
anemone
False Clown Anemonefish
Leathery Sea anemone
Haddon’s Sea anemone
Medusa form:
Feeding
• Each cnidocyte
• Tentacles then bring
contains bulb-like
the paralyzed prey
nematocysts
into the cnidarian’s
mouth
• Each nematocyst
contains a barbed,
coiled structure that
pierces prey when
triggered by touch
or chemicals
Digestion
• Nematocysts
– Tiny, harpoon-like
structures found at the
tips of tentacles that are
used to poison and
immobilize prey.
• Gastrovascular Cavity
– Inner body layer where
digestion takes place via
enzyme release
Cnidrian Oxygen Demands
• O2 diffuses directly into the body cells
from water
• CO2 and other wastes diffuse out of the
cells
Cnidarian Nervous System
• Nerve Net
– Conducts nerve impulses from
all parts of the body
– No brain (control center)
– Causes contractions of
muscle-like cells in the
tentacles and bodies
Reproduction in Cnidarians
• Alteration of Generations
– Male releases sperm and female
releases eggs into water (sexual)
– Zygote becomes a free-swimming
larva and swims to a suitable area
for attachment and settles
– Polyp then grows and begins to
form buds that become tiny
medusa (asexual)
– One by one, the medusa move
away from the parent polyp and
the cycle begins again
Jellyfish are categorized into
4 classes as follows:
• Hydrozoa (Portuguese man-of-war
• Scyphozoa (true jellyfish; most common)
• Cubozoa (box jellyfish; most toxic. NOT
found in Caribbean)
• Anthozoa (sea anemones and corals)
Class Scyphozoa
• Range in size from
the thimble sized
jellyfish to the
Arctic Lion’s Mane
whose tentacles
stretch over 100
feet in length
Scyphozoa Characteristics
• Found Worldwide
• 95% water
• No heart, brain,
blood or gills
• Feed on zooplankton
Scyphozoa Structure
• Bell
– Body of jellyfish
•
Oral Arms
– Help bring food toward mouth
• Mesoglea –
– “jelly-like” substance
– Separates and connects the two
other tissue layers
• Tentacles
– Contain Nematocysts
Scyphozoa Tissue Layers
•Gastrodermis –
•Inner tissue layer
– outermost tissue
•Lines the body cavity
layer
•Carries out digestion
– Acts like a “skin”
•Produces reproductive
– Provides protection
cells
• Epidermis –
Scyphozoa Senses
• Chemoreceptors
– Sense chemical signals
for smell and taste
• Balance
– Sacs located on rim of
bell
– Help keep the jellyfish
in the right direction
How Do Jellyfish Swim?
• Jet Propulsoion
– Contract
coronal muscles
that push water
out of the
hollow bell
– Drift in the
currents
Stinging Cells- Nematocysts
• Consist of a capsule
with a sensory hair, a
lid, and a interior
stinger
• Fires in milliseconds
– One of the fastest
processes in nature
Scyphozoa Reproduction:
Alternation of Generations
Miscellaneous Facts
• Nematocysts may still fire
even when the jellyfish is
dead
• Loggerhead Sea turtles
and Ocean Sunfish are
known to eat jellyfish
• The name of the “jellylike” material is called
Mesoglea
Class Hydroza-
Portuguese man-of-war
• Not only is it not a jellyfish, it's not even
an "it," but a "they."
• The Portuguese man-of-war is a
siphonophore, an animal made up of a
colony of four separate polyps called
zooids, that serve different functions and
act like different body parts of a single
organism.
• Commonly in the Pacific and Indian oceans,
and the northern Atlantic Gulf Stream,
although found in warm seas throughout
the world
• a translucent structure tinted pink, blue,
or violet - which may be 3 to 12 inches
long and may extend as much as 6 inches
• Will eat anything it can get
• Sting is excruciatingly painful
Purple Jelly
– Up to 5 inches
– Cape Cod to Florida
– Purple bell is
dotted red
– Sting: painful
Moon Jelly
– Size: 3-20 inches
– Atlantic Coast
– Color: translucent white
pink or beige
– Sting: Mild
Cannonball Jelly
– Size: Up to 1 foot
– North Carolina to
Florida
– Sting: Mild
Lion’s Mane Jelly
• Up to 8 ft
• Maine to Florida
• Color: Deep red,
purple or yellow
• Sting: Painful
Sea Nettle Jelly
• Size: 1-12 inches
• Cape Cod to Florida
• Color: Semi-transparent,
reddish stripes
• Sting: Painful
Upside Down Jellyfish
• Appearance provides protection
from predators (looks more like a
water flower)
• Crabs tend to carry these on their
backs for protection
• Depend on zooxanthellae for
partial nutrition
– Reason why it lives upside down (the
algae live inside the bell and needs
sunlight, so the jellyfish floats upside
down in the water, and lives in shallow
water so it can rest on the bottom
upside down)
Class Cubozoa - Box Jellyfish
• Characteristic cube-like
shape
• Nineteen species in this
group
• Sea wasps are best known
and most deadliest
creature on land or water
– Determined by how many
people an ounce of the venom
can kill, and how long it takes
you to die from the venom
after being bitten, stung, or
stuck
Box Jelly Stings
• An ounce of sea wasp venom can
kill 60 adult humans and can cause
death in less than 3 minutes
• Only one survivor has been
recorded (Ian McCormick from
New Zealand). He survived 5 stings
on his arm
• A single tentacle can have 5000
nematocysts
• Have 4 eyes, but no brain so we
don’t know what they see
• Normally found around Australia,
New Zealand, Hawaii and
Philippines
• Mostly found in shallow water and
like the intersection of the ocean
and rivers if there are any
• There has been an explosion around Australia,
attributed to climate change and reduction of
jellyfish predators due to over fishing.
• Number of deaths has risen
• Protection: special wetsuits, nylon pantyhose
Class Anthozoa –
sea anemones and corals
• Characteristics:
– are stinging polyps that spend most of their time
attached to rocks on the sea bottom or on coral reefs
waiting for fish to pass close enough to get ensnared in
their venom-filled tentacles
• Anatomy:
– Sea Anemones come in many shapes, sizes, and colors.
– Radially symmetric, they have a columnar body with a
single body opening, the mouth, which is surrounded by
tentacles.
– The tentacles protect the anemone and catch its food;
they are studded with microscopic stinging capsules.
Class Anthozoa –sea anemones
• Diet:
– Sea Anemones are carnivores that eat fish,
mussels, zooplankton (like copepods, other small
crustaceans, and tiny marine larvae), and worms.
– They catch food using the tentacles, which have
poisonous stingers (called nematocysts).
Class Anthozoa –sea anemones
• Mutualism:
– Clown fish always live near anemones;
they are immune from (and protected
by) the stinging tentacles. The clown
fish help the anemone by cleaning the
tentacles (as the fish eat detritus) and
perhaps by scaring away predators.
– Some anemones, establish symbiotic
relationships with green algae. In
exchange for providing the algae safe
harbor and exposure to sunlight, the
anemone receives oxygen and sugar.
– Sometimes sea anemones hitch a ride
on hermit crabs or decorator crabs.
The sea anemone can protect the crab
and if the crab is a messy eater, the
sea anemone can pick up bits of food
from the crab and eat it