1. Phylum Echinodermata
Biology 11

2. Definition Echino- = “spiny”; dermis = “skin”
Characteristics of Echinoderms:
-spiny skin, covering a hard calcium carbonate plate-like endoskeleton

3. Definition More characteristics of Echinoderms: -water vascular system
-tube feet (suction-cup like structures)
-radial symmetry
-deuterostomes (blastopore develops into anus)
-true coelomates

4. Body symmetry Echinoderms have five-part radial symmetry
Their larvae, however, have bilateral symmetry (like humans)

5. Form and Function
Echinoderms have a water vascular system, filled with fluid
This system consists of canals that extend throughout the body and opens to the outside through a madreporite

6. Water Vascular System
Madreporite connects to ring canal, which connects to radial canals
Attached to the radial canal are hundred of tube feet

7. Feeding Use of tube feet to capture prey or plankton
Can be herbivores (plankton)
Can be carnivores (mussels, clams)
-ex. Sea stars can pry prey’s shell open, push stomach out and pour digestive enzymes into prey, then pull stomach back in

9. Respiration and Circulation
Thin-walled tissue of tube feet allow respiration
Skin gills (in some species)
Circulation provided by water vascular system (carries oxygen, food, wastes)

10. Excretion Solid waste through anus
Metabolic waste (ammonia) through tube feet and skin gills

11. Response Simple nervous system with no brain
Have nerve rings around mouth, and radial nerves
Scattered sensory cells for light, gravity, chemicals

12. Movement Use tube feet and muscle fibres attached to endoskeleton
Some have flexible joints or movable spines
Tube feet

13. Reproduction External fertilization Sexes are separate
Sperm and eggs released into water  fertilization  larvae  adults

14. Groups of Echinoderms - 1
Class Echinoidea (Sea urchins and sand dollars)
-have large solid plates that form a box around their internal organs

15. Groups of Echinoderms - 2
Class Ophiuroidea (Brittle stars)
-have slender, flexible arms that can be shed to distract predators

16. Groups of Echinoderms - 3
Class Holothuroidea (Sea Cucumbers)
-warty, moving pickles

17. Groups of Echinoderms - 4
Class Asteroidea (Sea Stars – most common)
-creep slowly on sea floor, carnivorous, regenerative ability

18. Groups of Echinoderms - 5
Class Crinoidea (Sea lilies and feather stars)
-filter feeders, long feathery arms

19. Once upon a time there was a wise man
The Starfish
-Anonymous
Once upon a time there was a wise man
who used to go to the ocean to do his writing.
He had a habit of walking on the beach
before he began his work.
One day he was walking along the shore.
As he looked down the beach,
he saw a human figure moving like a dancer.
He smiled to himself to think of someone
who would dance to the day.
So he began to walk faster to catch up.
As he got closer, he saw that it was a young man
and the young man wasn’t dancing,
but instead he was reaching down to the shore,
picking up something and very gently
throwing it into the ocean.
As he got closer he called out,
“Good morning! What are you doing?”
The young man paused, looked up and replied,
”Throwing starfish in the ocean.”
“I guess I should have asked, why are you throwing starfish in the ocean?”
“The sun is up and the tide is going out.
And if I don’t throw them in they’ll die.”
“But, young man, don’t you realize that there are miles and miles
of beach and starfish all along it.
You can’t possibly make a difference!”
The young man listened politely.
Then bent down, picked up another starfish and threw
it into the sea, past the breaking waves and said-
“It made a difference for that one.”

20. Comparing Invertebrates
Chapter 29

21. So many INVERTEBRATES…. how much do you remember?.....
Try not to look at your notes or textbook and see how much you know!

22. Evolutionary Trends Specialized cells, tissues, organs little - none
sponges and cnidarians
simple organs
flatworms
mollusks and arthropods
organ systems

23. Evolutionary Trends Body Symmetry Sponges asymmetry
Cnidarians and Echinoderms
radial symmetry
Worms, mollusks, arthropods
bilateral symmetry

24. Evolutionary Trends Cephalization Sponges and cnidarians none
Most worms and arthropods
ganglia
brain
Certain mollusks

25. Evolutionary Trends Coelom Formation Sponges and cnidarians none none
Flatworms
Roundworms
pseudocoelom
Annelids
true coelom
Mollusks, arthropods, echinoderms
true coelom

26. Evolutionary Trends Early Development none Sponges and cnidarians
Worms, mollusks, and arthropods
protostome
deuterostome
Echinoderms

27. Feeding Both: cnidarians and flatworms Simple: Intracellular digestion
sponges
Complex:
Extracellular digestion
-incomplete  complete digestive system
Annelids, arthropods, mollusks, echinoderms
Both: cnidarians and flatworms

28. Respiration Diffusion Increase in specialized organs and surface area
Gills and book gills
Lungs and book lungs, tracheal tubes, spiracles

29. Circulation Closed circulatory system:
-heartlike organ forces blood through vessels throughout body
Annelids, mollusks
Open circulatory system:
-heart pumps blood through vessels into sinuses
Mollusks, arthropods
Echinoderms: water vascular system

30. Excretion Aquatic invertebrates – diffusion
sponges, cnidarians, roundworms
Terrestrial invertebrates
-nephridia – annelids, mollusks
-Malpighian tubules – insects, arachnids

31. Response Centralization -nerve nets – cnidarians Cephalization
-ganglia – mollusks, arthropods
Specialization
-eyespots, specialized sense organs to detect light, sound, chemicals, movement, direction of gravity, etc.

32. Movement Hydrostatic skeleton -cnidarians, annelids Exoskeleton
-arthropods
Endoskeleton
-echinoderms

33. Reproduction Asexual reproduction -fragmentation, budding, division
-separate sexes, or hermaphrodites
-internal fertilization or external fertilization

34. Very good! How did you do? 
The End!
Very good! How did you do? 