Transcript Echinoderms: The Spiny Animals!

Echinoderms: The Spiny
Animals!
Bethany Anding
Characteristics
• There are about 6,000
species of Echinoderms.
• Sea Stars, Sea
Cucumbers, Sea Urchins,
and Sand Dollars
• Echinoderms have radial
symmetry, an endoskeleton, a
water vascular system and a
coelomic circulation and
respiration system
• Echinoderms do not have a
brain or complex organs
Spiny Skin
• Radial symmetry
– Most echinoderms have a central point from which limbs grow out of
• Endoskeleton
– Ossicles fuse to form joints, muscle attachment sites, and shell like
protection
– Most ossicles grow upward through skin
• Water-vascular system
– Interconnected canals and tube feet that form a water-filled system
• Tube feet are how most echinoderms move across the sea floor
• Coelomic circulation and respiration system
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– Body cavity is the circulatory system
– Skin Gills clean out the air for the echinoderms, taking in the air
particles needed and getting rid of the ones not needed
http://videos.howstuffworks.com/hsw/16841-animals-without-backbonesechinoderms-video.htm
Sea Stars
• Sea Stars are also known as star fish
• Classification
– Class-Asteroidea
• There are about 2,000 species of sea stars
– Orange Marble Starfish
– Fromia Ghardagana (Ghardaga Brittle Star)
– Gomophia Egyptiaca (Egyptian Sea star)
• Known to be in marine waters
– It can be on rocky, sandy and muddy sea floors
• Sea stars are found in shallow waters
Sea Stars cont..
• Uses
– Marine aquariums
• Carnivores
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Clams
Oysters
Coral
Fish
• Tube feet
– Attach to shell and pries open
• Stomach
– Sea stars push their stomach
through their mouth to digest prey
– The stomach releases digestive
enzymes that puree the flesh of
their victim so the sea star can
absorb it
• Hard-skinned animals
– Not fish
Reproduction
Sexual
1. Huge amounts of eggs and sperm are released
2. Fertilization is external
3. The Embryos are very tiny
• Transparent and bilateral symmetry
4. Ocean currents carry the embryos for about two months
• They form part of zooplankton
5. Grow by eating phytoplankton
6. Grow out of zooplankton and develop radial symmetry
Asexual
1. An arm is split off of a sea star
2. This limb grows into an independent sea star
3. Original sea star re-grows limb
Sand Dollar
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Classification
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There are about 1,000 species
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Class-Echinoidea
Arrow head
Flat Round
Sea Biscuits
Pancake
Sea Gopher
Marine Waters
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Be buried under a layer of sand on the sea floor
Found in intertidal zone (between high and low tide)
Also found in subtidal zone (below low tide)
Usually found in shallow waters
Sand Dollars cont…
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Usually
• 7.5 cm in diameter
• 1 cm thick
• 5 to 10 cm wide
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Usually purple-blue
– Can fade due to location
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Has no arms or legs
Move with the tiny spines that surround their body
– The fine layer on the top of the sand dollar
• There are also tube feet on the top
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Slow moving grazers
– Mouth is sitting on the ground
– They eat disintegrating organic materials within their sand beds
• Tiny particles of food that float in the water
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Eaten by
– Sea stars
– Snails
• Sand dollars only have a spine when they are alive
• Their dead shell is called a test
– Scientist have traced sand dollars tests’ to the Ordovican period
• They cannot live out of the water
• Use tube feet to breathe
– Tube feet take in oxygen from water, the oxygen passes through
their tiny layer of skin
• Uses
– Sand dollar eggs have been used to better understand cell
division and things related to uncontrolled cell growth
• Cancer
Reproduction
• Sexual
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Gonads swell in May
• This lasts until July or August
– Dendraster discharges eggs that are ripe through the gonopores
– Fertilization is external
• Male protrudes his genital papilla from body wall so the sperm can travel
farther to get to the egg externally
– In 2-4 days four armed larvae are developed and become part of the
zooplankton
• When first hatched sand dollars are bilaterally symmetrical
• They also have several arms to feed
– Eggs can travel away from parent bed while in the ocean currents
• Larvae develop
– Chemical signals are produced
– The sand dollar settles in a sand bed and undergoes metamorphosis to
grow into an adult sand dollar form
Sea Urchins
• Sea Urchins are often known as the “hedgehog of the sea”
• Classification
– Class Echiniodea
• There are about 6,000 living species
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The biggest is the red sea urchin (18cm)
Pencil sea urchin
English channel sea urchins
Whole sputnik sea urchin
Purple sea urchin
Jewel case sea urchin
• Marine Waters
– Found from shallow waters to waters of great depth
– Tide-pools
– Also found on the oceans bottom
Sea Urchins cont…
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Uses
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Color
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Can range from .5cm-38cm
Diet
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Most common is purple-light pink
Also brown, black, green, white, or red
Size
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In the West Indies people eat the sea eggs (ovaries) of the sea urchin raw or fried
Sea Urchins also evoke the flavor of caviar
Kelp, seaweed, algae, dead fish, sponges, mussels, barnacles, bits of plants and animals,
and decaying matter
Mouth
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The sea urchin’s mouth is claw like (Aristotle’s lantern)
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5 tooth-like plates that point towards each other
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They help trap small particles like algae
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Continue to grow throughout lifespan
Pull, tear, rip algae off rocks
The mouth is located in the middle of the back side
The anus and genital spores are on the top side of the sea urchin
Sea Urchins cont…
• Predators
– Some birds, humans, fish, sea otters, sunflower stars, snails, and crabs
• Movement
– Sea Urchins have no arms or legs, but have long spines that replace
them
– These spines are used to move, catch prey, and as a defense
mechanism
– There are also five paired rows of tube feet with suckers
• These help them move and catch prey also
• They also help the urchin hold on to the sea floor
– Spines have toxin sacs on that are very fragile
• When one steps on a spine the sac erupts and the venom is injected into the
victim
• Tests
– The sea urchins’ tests have traced the animal back to 500 million years
ago
Reproduction
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Females release several million
jelly-coated eggs at a time
– The eggs or sperm are released
through five gonopores
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Fertilization is external
Development
– Larvae (pluteus)
• Have bilateral symmetry
– Larvae swim in sea alone with the
zooplankton
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Several months of development
for a juvenile sea urchin to form
The bottom and top side are
formed and they settle on the sea
floor
This lasts about 2 to 5 years
Sea Cucumbers
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Also known as Holothurians (coral reef)
Class-Holothurioidea
It is known that they have been around for 400 million years
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There are about 1,250 described species
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Silurian Period
White-Spotted Sea Cucumber
The Edible Sea Cucumber
The Light-Spotted Sea Cucumber
Alabaster Worm Cucumber
Mostly marine waters
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Fine sand and mud
Shallow waters
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Deep waters
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Exposed to the surface
Some on algae
Others bury on the sea floor
Life span
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5 to 10 years
Some can live very long as plankton
Sea Cucumbers cont…
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Omnivore
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Tiny marine animals, dead and decaying organic matter
Color
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Most are black, brown, or olive
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Size
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Can range from 2 to 200cm long and 1 to 20cm thick
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There has been a sea cucumber measuring 5 meters!
Soft-bodied
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Spherical to long and worm like
Bumps/warts
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Can be brightly colored or patterned
Cucumber or sausage
leathery
Uses
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Asia
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Tropical islands
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Soup, stews, stir-fries
Many dishes
Threads for protection against coral reef
Natives of Alaska
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Canned sea cucumbers
Sea Cucumbers cont…
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Predators
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Fish and many other marine animals
Protection
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Cucumbers eject long sticky threads through the anus to wrap up their enemy
Internal organs pushed out that releases a toxin that is deadly to fish
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Organs grow back in about six weeks
Movement
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Sea cucumbers have five rows of tube feet that provide movement
Some sea cucumbers can swim
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Podia
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Feet
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8-30 rows that surround mouth
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Scattered
These help capture food and help with burrowing
Non-radial appearing
Calcareous ring that surrounds throat
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Deep sea
Attachment point for controlling muscles
Circlet or oral tenticles
Ossicles are very small
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wheels
Reproduction
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Sexual has two stages
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Gametogenesis and spawning
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Gametogenesis
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Spawning
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Release of gametes in water
broadcasts and brooding
» Let free
» Males catch their eggs with tentacles and put them on their lower part of their body
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The male lifts anterior end and releases gametes
Females follow
The fertilization is external
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Larva float in ocean until it finds an appropriate place
Larvae transform into juvenile sea cucumbers
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Formation of sperm and ova
Many to be successful
Asexual
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Transverse fission (3 ways)
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Attach anterior to posterior tube feet
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Divide into 3 parts
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Attaches both ends and bloats gut
» Twists and body wall ruptures
Divides into halves
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Thins the middle of the body
» Middle breaks
Attaches both ends and bloats gut
» Twists and body wall ruptures
Regenerate either the anterior or posterior end, which ever one was lost
Question 1
☺ What is the most commonly known
echinoderm?
a.
b.
c.
d.
The brittle star
The sand dollar
The sea urchin
The sea star
Question 2
☻ Which echinoderm does not have
asexual reproduction?
a.
b.
c.
d.
Sea star
Sea cucumber
Sand dollar
None of these
Question 3
♂ What are some common uses of sea
cucumbers?
a.
b.
c.
d.
Marine aquariums
Many Asian Foods
To better understand cell division
All of the above
Question 4
• T or F
– Sea Urchins are known as the hedgehog of
the sea.
Question 5
۞ There are about ______ species of
echinoderms.
a.
b.
c.
d.
4,500
6,000
8,000
10,000
Sources
• http://www.cyhaus.com/marine/Echinoder
m.htm
• http://www.oceaninn.com/guides/echino.ht
m
• http://www.enchantedlearning.com/subject
s/invertebrates/echinoderm/Seastarprintou
t.shtml
• http://www.wetwebmedia.com/seastars.ht
m