Echinoderms

1
Echinoderms

• The Starfish

2
Distinguishing Characteristics

• Radial Symmetry
• Endoskeleton
• Tiny, jaw-like pinchers on skin
• Uses hydraulic suctions on limbs to move
• Water Vascular system

3
Types of Echinoderms

• Sea stars
• Brittle stars
• Sea urchins and sand dollars
• Sea cucumbers
• Sea lilies and feather stars

4
Symmetry

• Bilateral in larvae

• Radial in adults

5
Endoskeleton

• Hard, spiny or bumpy endoskeleton
• Thin epidermis (skin)
• Made of calcium carbonate (limestone)

• Endoskeleton of a starfish

6
Pedicellariae

• Tiny, jaw-like pinchers on skin
• Used for
• Protection
• Self cleaning

7

• Pedicellariae on sea urchin
• Pedicellariae on sea star

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Hydraulic Suction

• Appendages have hundreds of suction cups
• Hydraulic suction
• Allow movement and gripping

9
Water Vascular System

• A hydraulic system that operates under water
  pressure
• Allows
• Movement
• Gas Exchange
• Capture of food
• Excretion

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Parts of the SystemMadreporite

• Opening where water enters
• Acts as a filter

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Tube Feet

• Hollow tubes ending in suction cup lining canal
  grooves on appendages
• Tube pressure controlled by ampullae

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Ampullae

• Miniature droppers that control suction in
  tube feet
• Ampulla and tube feet

13
How the Water Vascular System Works

• Water enters ring canal through madreporite
• Moves to radial canals of rays
• Goes into ampulla, which contract and relax
• Suction in tube feet is created and released

14
Sea Stars

• Five rays (arms) or more.
• Stomach goes out of mouth, digests prey and then
  pulls back in
• Pedicellariae
• Eye spots
• Tube feet

15
Regeneration in Sea Stars

• Sea stars can grow back broken segments

16
Sea Cucumbers

• Tentacles tube feet for locomotion
• When threatened rupture, release organs, and
  then regenerate.

17
Brittle Stars

• Very fragile.
• Break when picked up and then escape.
• Regenerate new rays

18
Sea Urchins

• Globe shaped
• Covered with spines
• Move with spines and tube feet
• Poison sacs near tips of spines in some.

19
Sand Dollars

• Disc shaped
• Spines in petal shaped pattern
• serve as gills on top
• Bring food to mouth on bottom

20
Sea lilies Feather Stars

• The only sessile echinoderms

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What are the following organisms?
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Name the following
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Name the following
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Name the following