Download Phylum Echinodermata

Phylum Echinodermata
Echinoderm Characteristics
=spiny /hedgehog skin
Marine or brackish
Pentamerous symmetry
= 1. 5-pt symmetry o calcium
carbonate
2. balance
Endoskeleton = mesoderm
Size moderate to large
Most free moving
Deuterostome (primitive)
Coelomocytes
Echinoderm Bauplan
No definitive head
Oral versus aboral
1. Skeleton
Dermal
Plates/ossicles that vary in shape:
a) massive/linked
b) hinged/pliable
c) sculpted/individual
Ambulacra/interambulacra
Arising features: a) spines
b) pedicellariae
Echinoderm Bauplan
Spines
Defense, may contain toxins
Pedicellariae
Defense, cleaning
2. Coelom
Enterocoelic, general, hemocoel,
WVS
3. Water Vascular System
Schematic and photographs of echinoderm tube feet
1
2
3
4
5
1
3
4
5
1. Ampulla
4. Tube foot
2. Lateral canal 5. Sucker
3. Body wall
Feeding and Digestion
1. Suspension Feeders
Crinoids =
Pinnules & ciliary mucous
Holothurians = Sclerodactyla
Dendritic/palpate tentacles
Asteroids
Supplemental to diet only
Ophiuroids
Mucous net or extension of arms
Feeding and Digestion
2. Deposit Feeders
Holothurians = Leptosynapta
Tentacles sweep surfaces
3. Carnivores
Asteroids
Tubefeet and stomach
Ophiuroids
Coil arms around food
Often capture prey in groups
http://www.youtube.com/watch?v=xwWsow4gsfo
4. Grazers = Echinoids
5. DOM = Concentricycloids
Excretion/Circulation/Respiration
No specialized organ
Coelomocytes
= phagocytize particles
Accessory structures:
papulae, podia, bursa,
respiratory tree
No closed circulation
Coelom, WVS, Hemal
system
Podia, gills, papulae
Specialized structures:
Respiratory tree (H)
Bursa (O)
Locomotion and Nervous System
Podia = tubefeet
Smooth muscles
Non-centralized NS
3 nervous networks:
Ectopleural - circumoral,
sensory
Hyponeural - deep oral,
motor function, motor fibers
& ganglia
Entoneural - aboral,
reduced in most classes,
absent in holothuroids,
important in crinoids
Sense Organs
1. Photoreceptors
Tubefeet
Eyespots at tip of arms
Cup ocelli
2. Chemoreceptors
Buccal tentacles
Oral tubefeet
3. Touch
Receptors
Reproduction/
Development
Most diecious
Variable number of gonads:
Echinoids (5), asteroids (10),
holothurians (1)
Deuterostome cleavage
Complex metamorphosis
= bilateral -> pentamerous
Some with direct development =
large yolky eggs
Echinoderm Taxonomy
Frank Fish 2010
Class Crinoidea
= sea lilies (flower like
appearance)
Most primitive
1. Stalked
Permanently attached
Cup-shaped calyx with
extending arms
Flexible stalk
2. Unstalked
Comatulids
Cirri, not stalk
Class Ophiuroidea
"snake-tail form” = brittle
stars, basket stars
largest and most successful
arms break off easily =
regeneration
mobile, writhing, serpent-like
motion
mouth = five moveable plates
teeth = modified spines
sac-like stomach in the central
disc bursae = brood chamber,
gas exchange
Class Asteroidea
Sea stars or starfish
flattened and flexible body
varying number (often 5) arms
or rays
non distinct central disc
oral surface faces the
substrate
"top side" = aboral surface =
anus
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2
3
Aboral and oral
view of a sea
star
1. Madreporite
2. Mouth
3. Ambulacral
Groove
2
1
3
1
Schematic and photograph of the dye
injected sea star watervascular system
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3
1
5
3
6
4
1
5
1. Madreporite
2. Stone canal
3. Ring canal
4. Radial canal
5. Ampullae
6. Tube feet
Schematic and slide of a cross section
through a sea star arm
3
7
5
2
1
4
3
6
10
8
1. Coelom
2. Dermal ossicle
3. Dermal branchia
9
4.
5.
6.
7.
Pyloric cecum
Spine
Radial canal
Pedicellaria
8. Radial nerve
9. Tube foot
10. Sucker
Schematic and photo of the
digestive system of Asterias rubens
(aboral surface removed).
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3
4
2
4
4
3
1.
2.
3.
4.
Anus
Pyloric stomach
Cardiac stomach (beneath pyloric stomach)
Pyloric caeca (digestive glands)
Close-up of pyloric and cardiac stomach
of Asterias rubens
1
3
2
1. Pyloric stomach
2. Cardiac stomach
3. Connection between pyloric
stomach and pyloric glands
Close up of pyloric caeca of Asterias
Schematic and photo of the
reproductive system of Asterias
(stomachs and pyloric ceca removed)
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1
2
2
1. Paired gonads
2. Ambulacral groove
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1
Photomicrographs of starfish larval
stages
1
Bipinnaria
1. Ciliated bands used
for feeding and
locomotion
2. Adhesive arms
3. Ciliated arms
2
Brachiolaria
3
Class Echinoidea
= sea urchins, heart urchins,
sand dollars
Globular, oval
Suckered podia
0.5-38 cm body size
Strongylocentrotus
droebachiensis, the
green sea urchin
1
2
3
Close-up of urchin skin
1. Spines
2. Pedicellariae
3. Tube feet
4
3
1
1. Teeth
2. Lips
3. Gills
4. Spines
1
2
3
4
2
Mouth = centrally located oral (flattened) side
Five teeth protrude, chewing apparatus = Aristotle’s
Lantern. consists of calcareous plates and muscles
Sea Urchin Internal Anatomy
Photomicrographs of sea urchin
larval stage
Class Holothuroidea
soft-bodied
tiny ossicles embedded in
leathery
orally-aborally elongated
cyclindrical body
tentacles surrounding the
mouth = modified tube feet
internal, highly branched
respiratory trees attached
to the cloaca
http://www.youtube.com/watch?v=
lKWSLg5PDiU
Sea Cucumber External Anatomy
Dorsal view
Ventral view
showing
modification
into a sole.
Holothuroid Internal Anatomy
Class Concentricycloidea
= sea daisies
Highly modified armless seastar
Discovered in 1986
Deep sea >1000m on wood
Less than 1cm in diameter
Resembles jelly medusa
Double ring of water vascular
system