The document discusses the key characteristics of echinoderms. It describes the five classes of echinoderms - sea stars, brittle stars, sea urchins, crinoids, and sea cucumbers. It outlines their physical features such as radial symmetry, water vascular system, tube feet, endoskeleton, and ability to regenerate. It also summarizes their sensory structures, reproduction, locomotion, digestion, gas exchange, and other biological systems.

1. http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/Content/sea-star-pair-758303-sw.jpg

2. Echinoderm Classes
Asteroidea – Sea Stars:
 Multiple arms radiating from
central disk
 Tube feet on bottom
Riley Galton
Asteroidea – Sea Stars:
 Multiple arms radiating from
central disk
 Tube feet on bottom
Ophiuroidea – Brittle Stars:
 Distinct central disk with snake like arms
 Tube feet lack suckers
http://photography.nationalgeographic.com/staticfiles/
http://environment.nationalgeographic.com/staticfiles/

3. Echinoderm Classes
Echinoidea – Sea Urchins and Sand Dollars:
 No arms, but 5 rows of tube feet
 Have muscles that can move
 spines
Riley Galton
Echinoidea – Sea Urchins and Sand Dollars:
 No arms, but 5 rows of tube feet
 Have muscles that can move
 spines
http://environment.nationalgeographic.com/staticfiles/
www.emiliogrossi.com/images/Photo
graphyiles/
Crinoidea – Feather Stars
and Sea Lilies
 Flexible arms used in
suspension feeding
 Haven’t changed in 500 million
years
http://lh6.ggpht.com http://image44.webshots.com

4. Echinoderm Classes
Holothuroidea – Sea Cucumbers
 Reduced endoskeleton
 Five rows of tube feet
Riley Galton
Holothuroidea – Sea Cucumbers
 Reduced endoskeleton
 Five rows of tube feet
Concentricycloidea – Sea Daisies
 Only two known species
 Disk shaped, less than 1cm in diameter
http://blog.case.edu/case-news/2008/03/06/seacucumber.jpg
http://www.sfu.ca/~fankbone/v/xyloplax.jpg

5. Echinoderm Sensory
Structures
 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/echinomm.html
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/echinomm.html

6. Echinoderm Reproduction
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
Riley Galton
http://www.biolbull.org/content/vol204/issue3/images/medium/cov
erfig.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

7. Body Cavity (Coelom)
 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
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/General%20Zoology%20Terminology.htm
http://biology.kenyon.edu/courses/biol112/Biol112WebPage/Syllabus/Topics/Week%207/Resources/coelom.GIF
http://www.britannica.com/EBchecked/topic/452108/perivisceral-coelom
http://www.und.nodak.edu/instruct/jvaughan/b151/VOCAB_vertebrates.html

8. Body Symmetry
 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
Julia Heunis
http://tbn2.google.com/images?q=tbn:KrJSbsj0l4ImqM:http://
photos.tobinhosting.com/d/117553-2/sea%2Burchins.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

9. Excretory System
 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
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

10. Olivia Heunis
http://universe-review.ca/I10-82-starfish.jpg

11. Skeletal Type
Echinodermata: “Spiny Skinned”
 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
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/File:Sanc0521.jpg

12. Other Unique Features
 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
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

13. More Unique Features
 Autonomy = The spontaneous
self amputation of an
appendage when the organism
is injured or under attack. The
autotomized part is usually
regenerated.

have more because of
regeneration
 mutable collagenous tissue ~
connect ossicles; can maintain
different positions without
much effort
Julia Heunis
 Autonomy = The spontaneous
self amputation of an
appendage when the organism
is injured or under attack. The
autotomized part is usually
regenerated.

have more because of
regeneration
 mutable collagenous tissue ~
connect ossicles; can maintain
different positions without
much effort
http://www.starfish.ch/reef/echinoderms.html

14. Nervous System
 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
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

15. Digestive System
 Complete digestive system
(tubular gut), mouth to anus.
(bottom to top)
 Crinoidia: filter-feed, use cilia
 Asteroidea: Cardiac (evert),
pyloric stomach, digestive glands
 Urchins: “Aristotle’s lantern”
(masticatory apparatus)
 Holothurians: suspension/deposit
feeders, use tentacles.
http://www.experiencefestival.com/a/Sea_star_-
_Internal_Anatomy/id/2099728
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: “Aristotle’s lantern”
(masticatory apparatus)
 Holothurians: suspension/deposit
feeders, use tentacles.
http://www.experiencefestival.com/a/Sea_star_-
_Internal_Anatomy/id/2099728
http://userwww.sfsu.edu/~biol240/labs/lab_17hydrostatics
k/pages/echinoderm.html

16. Locomotion/Musculature
 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)
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/resources/biodidac/basicechino.jpg/mediu
m.jpg
http://userwww.sfsu.edu/~biol240/labs/lab_17hydrostaticsk/pages/echinoderm.html

17. Gas Exchange
 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"
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/animalstructure/outlines/echinode
rmata.html

18. Circulatory System
 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.
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/animalstructure/outlines/
echinodermata.html
http://www.dailygalaxy.com/photos/uncategorized/urchins_1.jpg

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

20. Answers
 Bilateral, radial
 Water vascular
system
 Regeneration
 Cardiac, pyloric;
evert and enzymes,
further digestion
 Bilateral, radial
 Water vascular
system
 Regeneration
 Cardiac, pyloric;
evert and enzymes,
further digestion