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Title: http:photography.nationalgeographic.comstaticfilesNGSSharedStaticFilesPhotographyImagesContentseasta


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Echinodermata
Riley Galton Julia Heunis David Lin
http//photography.nationalgeographic.com/staticfi
les/NGS/Shared/StaticFiles/Photography/Images/Cont
ent/sea-star-pair-758303-sw.jpg
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Echinoderm Classes
Riley Galton

• Asteroidea Sea Stars
• Multiple arms radiating from central disk
• Tube feet on bottom

http//photography.nationalgeographic.com/staticfi
les/

• Ophiuroidea Brittle Stars
• Distinct central disk with snake like arms
• Tube feet lack suckers

http//environment.nationalgeographic.com/staticfi
les/
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Echinoderm Classes
Riley Galton

• Echinoidea Sea Urchins and Sand Dollars
• No arms, but 5 rows of tube feet
• Have muscles that can move
• spines

www.emiliogrossi.com/images/Photographyiles/

• Crinoidea Feather Stars and Sea Lilies
• Flexible arms used in suspension feeding
• Havent changed in 500 million years

http//environment.nationalgeographic.com/staticfi
les/
http//lh6.ggpht.com
http//image44.webshots.com
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Echinoderm Classes
Riley Galton

• Holothuroidea Sea Cucumbers
• Reduced endoskeleton
• Five rows of tube feet

http//www.sfu.ca/fankbone/v/xyloplax.jpg

• Concentricycloidea Sea Daisies
• Only two known species
• Disk shaped, less than 1cm in diameter

http//blog.case.edu/case-news/2008/03/06/seacucum
ber.jpg
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Echinoderm Sensory Structures
Riley Galton

• Eyespots on the ends of ambulacra are sensitive
  to light
• Pedicellariae (jaw like skeletal structures used
  to keep organisms from settling on skin), tube
  feet, and spines are sensitive to touch
• http//www.ucmp.berkeley.edu/echinodermata/echinom
  m.html

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Echinoderm Reproduction
Riley Galton
http//www.biolbull.org/content/vol204/issue3/imag
es/medium/coverfig.gif

• Sexual
• Eggs and sperm are released into the water where
  they are fertilized
• Larvae are planktonic
• Internal fertilization has been observed in
  certain species of sea stars, brittle stars, and
  sea cucumbers
• Asexual
• Echinoderms can regenerate body parts and organs
• Asexual reproduction can occur (though not by
  will) if the echinoderm is torn with enough of
  the body on each part
• http//www.oceaninn.com/guides/echino.htm

http//www.starfish.ch/Fotos/echinoderms
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Body Cavity (Coelom)
Julia Heunis

• PRESENT!
• Coelom A fluid-filled cavity between body wall
  and gut lined by mesoderm
• Two parts
• Perivisceral coelom large, fluid-filled cavity
  where major organs, digestive tube and sex
  organs, are suspended
• Water Vascular System - network of hydraulic
  canals unique to echinoderms that branches into
  extensions (tube feet) which function in
  locomotion, feeding and gas exchange

http//www.colin.edu/science/awashington/syllabi/G
eneral20Zoology20Terminology.htm http//biology.
kenyon.edu/courses/biol112/Biol112WebPage/Syllabus
/Topics/Week207/Resources/coelom.GIF http//www.b
ritannica.com/EBchecked/topic/452108/perivisceral-
coelom http//www.und.nodak.edu/instruct/jvaughan/
b151/VOCAB_vertebrates.html
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Body Symmetry
Julia Heunis
http//tbn2.google.com/images?qtbnKrJSbsj0l4ImqM
http//photos.tobinhosting.com/d/117553-2/sea2Bu
rchins.jpg

• evolved from animals with bilateral symmetry
• adult echinoderms possess radial symmetry
• All echinoderms exhibit fivefold radial symmetry
  in portions of their body at some stage of life
  (5 parts around central axis), even if they have
  secondary bilateral symmetry
• For the most part
• LARVAE bilateral
• ADULTS radial

http//en.wikipedia.org/wiki/Echinoderm
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Excretory System
Julia Heunis

• NO true excretory system!
• Main opening of a sponge used only to EXPEL WASTE
• Anus leads directly from stomach/digestive tract
• Anus top
• mouth bottom

universe-review.ca
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Olivia Heunis
http//universe-review.ca/I10-82-starfish.jpg
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Skeletal TypeEchinodermata Spiny Skinned
Julia Heunis

• DO NOT possess an exoskeleton
• a thin outermost skin covers a mesodermal
  endoskeleton made of tiny calcified plates and
  spines - forms rigid support contained within
  tissues of the organism
• Skeleton composed of skeletal plates called
  ossicles
• Ossicles small bones
• In some species, such as the sea urchin, plates
  of the skeleton are locked together to form a
  rigid structure.
• most sea stars and brittle stars can flex their
  arms skeleton has gaps, flexible plate
  junctures

http//ebiomedia.com/prod/BOechinoderms.html http
//en.wikipedia.org/wiki/FileSanc0521.jpg
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Other Unique Features
Julia Heunis

• Echinoderms can REGENERATE
• ex sea cucumbers can eject a portion of gut in
  response to predators and regenerate when safe
• Water vascular system (described earlier) is
  unique to echinoderms varies water pressure to
  control tube feet
• Crinoids and some brittle stars passive
  filter-feeders, absorbing suspended particles
  from passing water
• sea urchins grazers
• sea cucumbers deposit feeders
• starfish active hunters

http//www.starfish.ch/reef/echinoderms.html
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More Unique Features
Julia Heunis

• Autonomy The spontaneous self amputation of an
  appendage when the organism is injured or under
  attack. The autotomized part is usually
  regenerated.
• arms ? multiples of 5 some have more because
  of regeneration
• mutable collagenous tissue connect ossicles
  can maintain different positions without much
  effort

http//www.starfish.ch/reef/echinoderms.html
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Nervous System
David Lin

• Decentralized
• central nerve ring surrounds gut, connect radial
  nerves.
• Radial nerves run under each arm, coordinate
  movement, etc.
• Do not have brains, but some have ganglia along
  radial nerves

http//www.tolweb.org/Echinodermata
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Digestive System
David Lin

• Complete digestive system (tubular gut), mouth to
  anus. (bottom to top)
• Crinoidia filter-feed, use cilia
• Asteroidea Cardiac (evert), pyloric stomach,
  digestive glands
• Urchins Aristotles lantern (masticatory
  apparatus)
• Holothurians suspension/deposit feeders, use
  tentacles.
• http//www.experiencefestival.com/a/Sea_star_-_Int
  ernal_Anatomy/id/2099728

http//userwww.sfsu.edu/biol240/labs/lab_17hydros
taticsk/pages/echinoderm.html
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Locomotion/Musculature
David Lin

• Utilize water vascular system and tube feet
• Water in from madreporite, pumped into ampulla by
  radial canal
• Ampulla contracts, water to podia
• Podia contracts, water to ampulla
• Podia bend, shorten allows movement (vacuum and
  suction)

http//animaldiversity.ummz.umich.edu/site/resourc
es/biodidac/basicechino.jpg/medium.jpg http//user
www.sfsu.edu/biol240/labs/lab_17hydrostaticsk/pag
es/echinoderm.html
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Gas Exchange
David Lin

• Asteroids, crinoids dermal gills (thin
  epidermis)
• Urchins infolds of body wall (bursae) opening to
  outside
• Sand dollars modified podia on top (petaloids)
  which are thin-walled and flaplike.
• Holothurians highly branched hindgut called
  "respiratory tree"

http//faculty.vassar.edu/mehaffey/academic/animal
structure/outlines/echinodermata.html
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Circulatory System
David Lin

• Mostly in perivisceral coelom, enhanced by water
  vascular system and hemal system.
• Hemal system series of canals and spaces mostly
  in coelomic channels. Fluid movement by cilia.
  Used to distribute nutrients. No respiratory
  system.

http//faculty.vassar.edu/mehaffey/academic/animal
structure/outlines/echinodermata.htmlhttp//www.d
ailygalaxy.com/photos/uncategorized/urchins_1.jpg
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Quiz

• Echinodermata have ________ symmetry as larvae,
  but display ________ symmetry as adults.
• What allows Echinoderms to function in
  locomotion, feeding and gas exchange?
• Sea stars can grow new arms and sea cucumbers can
  replace their gut after ejecting them. What
  feature of echinoderms does this demonstrate?
• Name the stomachs of a sea star. Functions?

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Answers

• Bilateral, radial
• Water vascular system
• Regeneration
• Cardiac, pyloric evert and enzymes, further
  digestion