1. Ch. 40 – Echinoderms Phylum: Echinodermata
Sea stars, sand dollars, brittle stars, & sea cucumbers
Marine
Usually 5 arms  pentaradial
No circulatory, respiratory, or excretory systems
Water-vascular system
Tube feet that aid in movement

3. Most invertebrates have an exoskeleton to support them
Most invertebrates have an exoskeleton to support them . Echinoderms have an endoskeleton, which is a skeleton within the body.
This is why echinoderms are thought to be closer related to vertebrates.

4. 5 Classes of Echinoderms
1. Ophiuroidea  brittle stars & basket stars
2. Crinoidea  sea lilies & feather stars
3. Holothuroidea  sea cucumbers
4. Echinoidea  sand dollars & sea urchins
5. Asteroidea  starfish & sea stars

5. Class: Ophiuroidea
Brittle stars
Gets it name brittle because its has long, thin arms and are constantly breaking off and regenerating.
Pg 791 & 785

6. Sea lilies & feather stars Sessile Pg. 792
Class: Crinoidea
Sea lilies & feather stars
Sessile
Pg. 792

7. Class: Holothuroidea
Sea cucumber
Soft body
If threatened the sea cucumber may eject their organs out of their body at the predator. They then regenerate their organs.
Pg. 792

8. Sand dollars & sea urchins
Class: Echinoidea
Sand dollars & sea urchins
They have an Aristotle’s lantern, which is a jaw-like structure for grinding their food.
Sea urchins have long spines with sometimes venom for protection
Sand dollars are about the size of a silver dollar.

9. Class: Asteroidea (sea star)
Body Structure (external)
Aboral surface  Madreporite is located (top side)
Oral surface  mouth is located (bottom side)
Ossicles  calcium spines
Pedicellarie  tiny little pinchers that clean the body surface so debris doesn’t collect.

10. Water- Vascular System
Used to create movement
Enters the madreporite  stone canal  ring canal  5 radial canals lateral canal  the tube feet (100s of tube feet), have ampulla (air sacs), that act like a pipette and release the water with pressure. Pg. 786

11. Body Systems
No circulatory, respiratory, or excretory systems.
Each arm has an eyespot at the end, which senses light and touch.
Digestion  They have digestive glands. Their tube feet are strong enough to open clams & mussels.

13. Reproduction  Each arm of the sea star has 2 gonads that produce eggs and sperm cells. They are hermaphrodites.
Sea stars can regenerate lost parts. A new sea star can regenerate from a segment of an arm as long as it has part of the ring canal attached.