Unit 4b journal #1 3/27

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Unit 4B Journal #1 3/27

  • Trace the path of water through the water vascular system.
  • What would happen to a starfish that had a mutation that caused the stone canal to be deformed?

Unit 4B Journal #1 10/23

  • What do these animals have in common?

Unit 4B 3/26

  • Please turn in your mollusk essay with rubric and pick up:

Unit 4B Journal #2 3/30

  • Starfish eat oysters. Oyster farmers use to scuba dive down and cut up the starfish to kill them. Explain why this was NOT an effective method to kill the starfish.
  • Journal: What do all of these organisms have in common?
  • Phylum Echino-dermata


  • Get an iRespond remote and complete Journal.
  • Use these words in a sentence related to one of the animals we’ve discussed this school year. Can you combine some of these so you don’t have to write 5 separate sentences?
    • Germane- relevant
    • Ignominious- shameful
    • Imminent- dangerous, close at hand
    • Factious- turbulent

What is the seive plate that filters water before it enters the water vascular system?

  • What is the seive plate that filters water before it enters the water vascular system?
    • Madreporite b. Pyloric caeca c. pedicellaria
  • Another name for the pyloric caeca is
    • Intestine
    • Anus
    • gonad
  • The pinchers on top of the body that are used to free skin of debris are called
    • Madreporites b. Pedicellaria c. Tiedeman bodies
  • What is responsible for movement, respiration, and circulation.
    • Pyloric caeca
    • Nervous system
    • Water vascular system
  • Which side of the starfish is shown?
    • Oral b. aboral

General Information

  • Echinoderm- “spiny skin”
  • Have water vascular system
  • Do not have true circulatory, respiratory, or excretory system
  • Pentaradial symmetry- body parts arranged in fives or multiples of fives around an oral (mouth) and aboral (anus) surface.


  • 1. Kingdom Animalia
  • 2. Phylum Echinodermata
  • 3a. Class Asteroidea
  • 3b. Class Echinoidea
  • 3c. Class Ophiuroidea
  • 3d. Class Holothuroidea
  • 3e. Class Crinoidea

IIIa. Class Asteroidea (sea stars)

  • A. Structure/Support
  • 1. Endoskeleton-
  • a. calcium carbonate plates called ossicles.
  • b. Spines- deter predators
  • 2. Pedicellaria- pinchers for protection & for keeping aboral surface clean of debris.

A. Structure/Support

  • Central disk- center part of starfish
  • Ambulacral groove- groove thru which tube feet stick out
  • Oral (ventral) surface
  • Central disk
  • Aboral (dorsal) surface
  • Arm/Ray
  • Spine
  • Water Vascular System- movement, respiration, circulation, some excretion
  • 1. Madreporite on aboral surface.
  • 2. Stone canal
  • 3. Ring canal
  • 4. Ring canal has Polian vesicles attached that allow for storage of water.
  • 5. 5 radial canals, one in each ray.
  • 6. Water enters hundreds of bubble-like sacs called the ampulla which inflate.
  • 7. Muscles are stimulated which contract ampulla and push water down a tube to the suction cup-like tube foot.
  • 8. The tube foot attaches to a surface creating movement.
  • Digestion/Feeding
  • 1. Mouth is on oral surface (underneath)
  • 2. Use rays & tube feet to grasp prey (clams)
  • 3. Opens shell 0.1mm, enuf to insert cardiac stomach.
  • 4. The pyloric caeca (digestive glands) release digestive enzymes that begin to dissolve prey.
  • 5. As the digestive enzymes work, the clam muscles weaken, making it easier to open.
  • 6. Partially digested food is taken to the pyloric stomach where it is absorbed and nutrients are passed to the pyloric caeca which transport nutrients throughout.
  • 7. Wastes leave thru the aboral surface thru anus.
  • 8. This process can take up to 8 hours depending on size of clam!

D. Respiration/circulation


  • 1. Tiedemann’s bodies- (in ring canal) filter water of debris
  • 2. Amoebocytes- collect debris & bodily wastes & excrete thru dermal gills.

F. Nervous/sensory system-

  • 1. Nerve ring around mouth
  • 2. Radial nerves in each arm (coordinate tube feet)
  • 3. Photosensitive eyespots at tip of each ray
  • Reproduction
  • 1. Asexual- regeneration
  • a. Can take up to a year
  • b. Some broken arms can regenerate entire body if central disk is attached

2. Sexual- dioecious

  • a. Gonads (ovaries-red, testes- white) in each ray
  • b. External fertilization
  • c. Gametes released thru gonopore at base of each arm
  • d. Release pheromones to induce gamete release among other starfish in area for spawning.
  • e. Larvae (bipinnaria) live amongst plankton until adult organs grow
  • IIIb. Class Echinoidea
  • Ex: sea urchins & sand dollars
  • Globe or disc shaped
  • No rays
  • Movable, hollow
  • spines- may be
  • venomous 5. Skeleton of 10
  • ossicle plates- test
  • IIIc. Class Ophiuroidea
  • Ex: brittle stars
  • Long narrow arms
  • Habitat- rocks, coral
  • Predators & scavengers
  • Use arms & tube feet in
  • sweeping motion to collect
  • prey which is then transferred to the mouth.
  • IIId. Class Holothuroidea
  • Ex: sea cucumbers
  • No rays
  • Elongate body
  • Circumoral tentacles
  • (surround mouth)
  • 5. No spines or pedicellaria
  • 6. “earthworms of the sea”- feed on detritus & turn over ocean soil
  • 7. Digestion- food trapped in net-like tentacles which are “licked” clean by mouth.
  • 8. Evisceration- eject mass of visceral organs when disturbed. Confuses predator.
  • IIIe. Class Crinoidea
  • Ex: sea lilies & feather stars
  • Usually sessile
  • Have fan-like appearance
  • Filter feeders

Environmental/Economical Significance

  • Sea urchin spines are poisonous if stepped on.
  • Sea urchin gonads are a delicacy in Asia.
  • Sea cucumbers are dried & eaten
  • Sea cucumber toxin used to kill tumor cells (may fight cancer)
  • Starfish are pests in oyster beds
  • Echinoderm carbonate skeletons can be ground up and used as lime to enrich soil
  • Source of food for many organisms in food web
  • Decorations

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