Download Cnidarians

Cnidarians
“The guys with the stinging
tentacles”
Cnidarians
• Cnidarians actually
exhibit radial symmetry
in which similar body
parts can be grouped
around a central axis.
• Here we also observe a
large jump on the
evolutionary scale:
tissues that perform
specific functions.
Phylum Cnidaria
The Classes of Cnidaria are:
• Anthozoa- Sea Anemones and Corals
• Hydrozoa- Hydra
• Scyphozoa- “true” jellyfish
• Cubozoa- “box-shaped” jellyfish
• Ctenophora- non stinging Cnidarians:
 Comb Jellies
**There are over 10,000 species of
Cnidarians
Cnidarians
• The word Cnidarian comes from the Greek,
“cnidos” which means “nettle”. Nettles, or
nematocysts, are stinging cells, and all
Cnidarians have them. These are some of the
oldest, largest and most poisonous creatures on
Earth.
Red striped sea nettle
Interesting Stuff
1. Jellyfish fact: Jellyfish have been around for more than 650 million years which
means that they outdate the dinosaurs and the sharks.
2. Jellyfish fact: Different species of jellyfish can be found in all the worlds’
oceans. Jellyfish can even be found in freshwater.
3. Jellyfish fact: A species of jellyfish, the Box jellyfish (sea wasp) kills more
people than any other marine creature.
4. Jellyfish fact: The worlds largest known jellyfish can reach a diameter of 2.5 m/
8ft and their tentacles can grow to be half the length of a football field.
5. Jellyfish fact: Jellyfishes uses jet propulsion to make their way through to
oceans of the world. Some swim while others mostly drifts with the currents.
6. Jellyfish fact: Some species of jellyfish contain a lot of protein and are thought
to be able to play a large role in ending hunger and malnutrition.
7. Jellyfish fact: Jellyfish is able to reproduce both sexually and asexually during
different parts of their lifecycles
8. Jellyfish fact: what enables them to survive is their stinging tentacles that
protect them from being preyed upon.
Characteristics of Cnidarians
• Two cell layers (epidermis, gastrodermis,
separated by jelly-like layer called
mesoglea)
• Stinging tentacles
• Sac-like digestive system
• Radial symmetry
• Tentacles are arranged in a circle around
the mouth
• Nerve net- simple nervous system
• invertebrate
Radial Symmetry
Radial
Compass jellyfish
Anatomy
A. Polymorphism- Cnidarians have
more than one body form:
1. Polyp
2. Medusa
Polyp Form
• Tube with tentacles
around the mouth
• Sessile
Coral polyp
Polyp (sea anemone)
Polyp (Hydra)
Medusa
• Umbrella shape
• Tentacles around mouth
• Motile, Free-swimming
Cnidocytes-Stinging Cells
• Within the cnidocyte is the
nematocyst (which is like a
capsule)
• The capsule has the stinging
structure which is a hollow
thread (Filament) with barbs
• Most contain a toxin
• Very small, but discharged in large
numbers
• Usually the sting is only strong
enough to kill zooplankton or tiny
fish
• But there are exceptions!
•
http://www.youtube.com/watch?v=6zJiBc_N1Zk
http://vimeo.com/37432287
• Discharged nematocysts,
stinging cells used for
defense and prey
capture, have been the
plague of more than fish.
• Stings from certain
jellyfish have resulted in
death in a matter of
hours, especially for
infants.
Habitat
Aquatic:
• Most are
marine
• A few are
freshwater
Feeding
1. Carnivores
(predators)
2. Process of feeding
Lion’s mane eats
a. Tentacles sting prey with
another jelly!
nematocysts
b. Tentacles grab prey
c. Prey pulled into mouth
3. Prey moved into gastro-vascular cavity (GVC)*
4. GVC makes enzymes, breaks down food, extra-cellular
digestion
5. Undigested food moves back out of mouth
Lion’s mane jellyfish eating
http://www.discovery.co
m/tv-shows/northamerica/animals/lionsmane-jellyfish.htm
RINGED ANEMONE
RETRACTED ANEMONE
Locomotion
A. Medusa- motile, free-swimming
B. Polyps- sessile, attached to hard
substrate
Exceptions:
1. Hydra tumbles on tentacles
2. Sea anemones glide on pedal
disc
Reproduction
1. Asexual
budding
2. Sexual
a. Medusae release
sperm & eggs
b. Larvae are freeswimming
Do Now
1. Explain how the jellyfish is adapted for
floating?
2. How do jellyfish capture and digest their
prey?
3. Describe how a typical jellyfish reproduces.
4. How does the adult form of a jellyfish differ
from that of a sea anemone?
5. How does a sea anemone obtain its food?
6. How does the sea anemone respond to
stimuli?
Class Anthozoa: Sea
Anemones
Sea Anemones (with sea urchins)
Sea Anemones with Clownfish
Clownfish & eggs with Sea
Anemone
Clown fish with sea anemone
Purple Tipped Sea Anemone
Rosy Sea Anemone
• Swimming Anemone
– http://www.youtube.com/watch?v=Dm98n3
908QM
Class Anthozoa: Corals
FORMATION OF CORAL
REEFS
CORAL REEFS ARE BUILT BY MILLIONS OF CORAL
POLYPS OVER THOUSANDS OF YEARS
EACH POLYP CREATES A “CUP” OF CALCIUM
CARBONATE TO LIVE IN
CORALS REPRODUCE ASEXUALLY BY BUDDING,
THIS PROCESS HELPS COLONIES TO GROW
POLYPS ARE
CONNECTED
OLD SKELETONS
• Create coral reefs at growths of ½ inch
per year
• Deposit skeleton of calcium carbonate
(limestone)
• Photosynthetic and symbiotic
dinoflagellates (zooxanthellae) live within
coral structure and provide energy to
growing coral.
FORMATION OF CORAL
REEFS
CORALS ALSO REPRODUCE SEXUALLY ONCE A YEAR
BY RELEASING SEX CELLS INTO THE WATER.
THIS HELPS TOP ESTABLISH NEW COLONIES
HARD CORALS
REEF BUILDERS – USE
CALCIUM FOR SKELETON
EACH SPECIES HAS A UNIQUE
COLONY & CUP DESIGN
EXAMPLES:
BRAIN,
ELKHORN,
STAR
Do Now
1. Why are coral reefs found only in tropical
water?
2. Compare the coral polyp with a sea
anemone. What are the similarities and the
differences?
3. Why is a coral polyp considered a colonial
animal?
4. What is the umbrella shaped structure
found in jellyfish?
5. The stinging cells inside tentacles are
called?
BRANCHING CORAL POLYPS
BRANCHING CORAL
LACE CORAL
BOULDER CORAL EXTENDED
BOULDER CORAL RETRACTED
ROSE CORAL
LETTUCE CORAL
FLOWER CORAL w/ ARROW
CRAB
Brain Coral
Elkhorn Coral
Staghorn Coral
Branched
Finger
Coral
Fire Coral
Antler Corals
Pillar Corals
Branching Coral
Orange Cup Coral
Sun Coral
Subergorgia Coral
Soft Corals – soft
and bendable
Flower Corals
Soft Corals are
non-reef
building corals.
They often do
not contain
zooxanthellae.
Wood-like
cores for
support and
fleshy rinds
Coral Polyps in the
Indo-pacific
Pulsing Xenias
http://www.youtube.com/watch?v=kbkscBSofcI
Sea Pen
Hammer / Anchor Coral
Sea Fan
Coral Bleaching
Coral Bleaching…
Class Hydrozoa: Green Hydra
Hydra
Brown Hydra with buds
Brown Hydra eating
Hydra eating Daphnia
• Hydra eats Daphnia
Class Scyphozoa: True Jellyfish
Fried egg jelly
Jellyfish
Jellyfish
Red-eyed medusa
Jellyfish
Jellyfish
Jellyfish
Lion’s mane
Jellyfish
Purple lion’s mane
Upside down Jelly fish
“Cassiopea”
Sea Nettle
Sea Nettle
Jelly and diver
Giant Jelly off Coast of Japan
Beached Jelly fish
Remember you can only touch
the tops!!!
Portuguese
Man 0’ War
(a Hydrozoan),
NOT a true
jelly fish
Portuguese Man 0’ War
Not a single animal, but a colony of
4 specialized cells that depend on
each other.
Tentacles of Physalia physalis
Class Cubozoa: Box Jellyfish
Chironex fleckeri
the Box jelly fish
Carukia barnesi: the badest of the bad!
Irukandji syndrome:
A sting from this little guy can cause the following:
“It begins with a mild sting, followed by severe lower back pain,
muscle cramps in arms, legs, stomach and chest. It causes
sweating, anxiety, nausea, vomiting, headaches and palpitations,
and has also been known to cause cardiac failure.”
Portuguese Man o’ War
vs. Box Jelly fish
COMB JELLIES
PHYLUM CTENOPHORA
BASIC CHARACTERISTICS:
“CTEN” REFERS TO FUSED
PLATES OF CILIA LOOK
LIKE A “COMB” STRUCTURE
DO NOT CONTAIN
STINGING CELLS
USE CILIA TO
FILTER WATER
TENTACLES ARE
STICKY TO CATCH
FOOD
Comb jellies: Ctenophora
Similar to cnidarians in
most
respects.
Nearly 100 species.
Contain cilliated combs
which assist in prey
capture and mobility.
Amazing Comb Jellies
• http://www.youtube.com/watch?v=bW3s
qB7RTIc
• Deep Sea Jellies
– http://www.youtube.com/watch?v=fLrGGUt
Of40
Aliens of the Deep