Phyla Echinodermata

1. Phyla
Echinodermata
Sarah Doyle & Lauren Dombkoski

2. Echinoderms
•a slow-moving or sessile marine
deuterostome with a water vascular system
and, in adults, radial anatomy
•6000 species, all marine

3. Living Echinoderms are divided
into six classes...
•1- Asteroidea: sea stars aka starfish
•- star shaped body with multiple arms; mouth
directed to substrate

4. Classes, continued
• 2- Ophiuroidea: brittle stars
•- Distinct central disk; long, flexible arms;
tube feet lack suckers

5. Classes, continued
•3 - Echinoidea: sea urchins and sand dollars
•- Roughly spherical or disk-shaped; no arms;
five rows of tube feet enable slow movement;
mouth ringed by complex, jaw-like structure

6. Classes, continued
•4 - Crinoidea: sea lilies and feather stars
•- Feathered arms surrounding upward-pointing
mouth

7. Classes, continued
•5 - Holothuroidea: sea cucumbers
• - Cucumber-shaped body; five rows of tube feet;
additional tube feet modified

8. Classes, continued
•6 - Concentricycloidea : sea daises
•- Disk-shaped body ringed with small spines;
incomplete digestive system; live on submerged
wood

9. Physical Description
•adult forms have radial symmetry
•larvae are bilateral
•varied skeletal and muscular arrangement
•water vascular system

•Respiration
•gills on the skin

10. Reproduction
•there are 2 sexes
except:
oasteroids&echinoids -
multiple gonads in arms
ocrinoids - lack distinct
gonads
oholothurians - single
gonad
•gametes are released
into water

11. Characteristics
•Behavior
•most are immobile
•water vascular system originally for food
collection but now evolved for locomotion
•Communication
•non-central nervous system: movement is
sense from all sides
•Development
•deuterostomes: anus forms first, then mouth

12. Food
•Crinoidea
•sit with arms out and collect passing food
•Asteroidea
•predators or scavengers; everts stomach
and secretes digestive enzymes on prey;
suspenson feeders, too
•Ophuroidea
•imcomplete digestive system; predators,
deposit feeders, and scavengers

13. Food, cont.
•Echinoidea
•suspension feeders,
herbivores, detritivores,
predators
•Holothuroidea
•suspension or deposit
feeders; use digestive
organs in response to threat
•group of hard plates that
retract and grasp like teeth

14. Execretion
•amoeboid cells carry wastes out of the body

15. Predation
•most vulnerable in larval stage
•asteriods:
oanti-predator adaptation
•holothurians
odischarge, sticky tubules called Cuvierian tubules

16. Starfish

Class: Asteroidea
Cirulatory System:
- Water-vascular system and tube feet
- hemal system
Nervous System:
- nerve plexus
- ringed nerves

17. Starfish
•Digestion and Excretion:
•- mouth is located on underside of the body
•- Has a digestive tract
•Reproduction:
•- each arm contains two gonads and releases
gametes into surrounding water
•- fragmentation
•Symmetry:
•- pentamerous symmetry

19. Feather Stars
•Class: Crinoidea
•Circulatory System:
•- Water-vascular system and tube feet
•- do not use tube feet for locomotion
•Nervous System:
•- Has small sensory cells throughout their skin
•- Central nervous ring around the mouth,
arms, and base

20. Feather Stars
•Digestion and Excretion:
•- Captures particles or plankton
•- Has a digestive tract
•Reproduction:
•- releases sperm and egg into surrounding
water
•Symmetry:
•- radial symmetry

22. Sea Urchin
•Class: Echinoidea
•Circulatory System:
•- Water-vascular system and tube feet
•Nervous System:
•- no true brain
•- Central nervous ring around the mouth

23. Sea Urchin
•Digestion and Excretion:
•- Has a mouth containing teeth, jaw, and
tongue like structure
•- Has a digestive tract
•Reproduction:
•- releases sperm and egg into surrounding
water
•Symmetry:
•- radial symmetry