Phylum Echinodermata: Phylum Echinodermata: EchinodermsEchinoderms

A. General CharacteristicsA. General Characteristics1. Echin- Spiny1. Echin- Spiny Dermis- SkinDermis- Skin2. Pentaradial: 5 part radial symmetry2. Pentaradial: 5 part radial symmetry3. Water Vascular System: System of internal 3. Water Vascular System: System of internal tubesinternal network of fluid filled canals connected to tubesinternal network of fluid filled canals connected to tube-feet. Involved in many processes:tube-feet. Involved in many processes:

feedingfeeding respirationrespiration internal transportinternal transport elimination of wasteselimination of wastes movementmovement

4. Tube-Feet: suction cup-like structures.4. Tube-Feet: suction cup-like structures.

StructureStructure

B. StructureB. Structure

1. No anterior, posterior, or brain1. No anterior, posterior, or brain

2. Two sides:2. Two sides:

a. aboraa. aboral- top of the bodyl- top of the body

b. oralb. oral- side where the mouth is - side where the mouth is located located

(hint to remember: orajel, oralB floss)(hint to remember: orajel, oralB floss)

3. Spiny skinned 3. Spiny skinned

MovementMovementC. Water Vascular SystemC. Water Vascular System

1. Sieve Plate 1. Sieve Plate (madreporite): located on the aboral surface(madreporite): located on the aboral surface water enters into the starfishwater enters into the starfish

2. Ring Canal2. Ring Canal: Surrounds the mouth: Surrounds the mouth Surrounds the mouthSurrounds the mouth

3. Stone canal3. Stone canal: carries water into the ring canal.: carries water into the ring canal.4. Five Radial Canals4. Five Radial Canals: These extend from the ring canal to each : These extend from the ring canal to each

body segment. Water moves from the ring canal into these radial body segment. Water moves from the ring canal into these radial canals. This is how water reaches the rest of the body.canals. This is how water reaches the rest of the body.

5. Tube-Feet5. Tube-Feet: Suction cup like structures: Suction cup like structures When water is pushed in- tube feet expandsWhen water is pushed in- tube feet expands

When water is pulled out- The ampulla shrinks creating a vacuum When water is pulled out- The ampulla shrinks creating a vacuum

suctioning to what it is touching. suctioning to what it is touching. 6. Ampulla6. Ampulla: Muscular sac at the base of each tube foot that : Muscular sac at the base of each tube foot that

contains fluid.contains fluid. HintHint: This is how a dropper works.: This is how a dropper works.

Feeding/ExcretionFeeding/Excretion Feeds on mollusks, worms, and other slow moving animalsFeeds on mollusks, worms, and other slow moving animalsD. Feeding Process:D. Feeding Process:

1. use tube feet to pry open shells of mollusks1. use tube feet to pry open shells of mollusks2. Once the shells are open, it flips its stomach out 2. Once the shells are open, it flips its stomach out

of of its mouth it pours out enzymes to digest the meat of its mouth it pours out enzymes to digest the meat of

the mollusk in its own shellthe mollusk in its own shell

3. when partially digested, the starfish pulls its 3. when partially digested, the starfish pulls its stomach back into its mouth to finish its mealstomach back into its mouth to finish its mealE. Excretion Process;E. Excretion Process;

1. diffusion through the thin walls of the tube feet1. diffusion through the thin walls of the tube feet2. diffusion through the skin gills.2. diffusion through the skin gills.

Respiration/Nervous SystemsRespiration/Nervous Systems

F. RespirationF. Respiration1. Exchange of oxygen(O2) and carbon dioxide (CO2) 1. Exchange of oxygen(O2) and carbon dioxide (CO2)

occurs through diffusion of skin gills and tube feet.occurs through diffusion of skin gills and tube feet.G. Nervous SystemG. Nervous System

1. Nerve Ring1. Nerve Ring: surrounds the mouth: surrounds the mouth2. Radial Nerves2. Radial Nerves: connects to the nerve ring. they : connects to the nerve ring. they

extend into each arm. extend into each arm. 3. Eyespots: located at the end of each arm, detect light3. Eyespots: located at the end of each arm, detect light4. Tube feet: sense touch4. Tube feet: sense touch5. Scattered sensory cells: sense chemicals 5. Scattered sensory cells: sense chemicals

Reproductive SystemReproductive System

H. ReproductionH. Reproduction1. Separate Sexes:1. Separate Sexes:

a. produce egg or sperm which fill the arms a. produce egg or sperm which fill the arms during the during the

reproductive season.reproductive season.b. eggs and sperm are released into open waterb. eggs and sperm are released into open waterc. starfish detect gametes of their own speciesc. starfish detect gametes of their own speciesd. respond by releasing their gametes (egg or d. respond by releasing their gametes (egg or

sperm) sperm) into the water.into the water.

e. fertilization occurs in the open water. e. fertilization occurs in the open water. 2. Regeneration2. Regeneration

a. this can occur if part of the central disc is present a. this can occur if part of the central disc is present

anatomy of a starfish   

                                                                                                                                         

ring canal ring canal Circular canal in which filtered water enters through the madreporite and branches out into the Circular canal in which filtered water enters through the madreporite and branches out into the

radiated canals. radiated canals.

rectal cecum rectal cecum Lateral duct of the terminal part of the digestive tract, where waste is stored before being expelled Lateral duct of the terminal part of the digestive tract, where waste is stored before being expelled

through the anus. through the anus.

anus anus Terminal orifice of the digestive tract allowing waste to be ejected; most of the undigested food is Terminal orifice of the digestive tract allowing waste to be ejected; most of the undigested food is

regurgitated rather than expelled through the anus. regurgitated rather than expelled through the anus.

stomach stomach Dilated section of the digestive tract preceding the intestine; it receives food to be digested. Dilated section of the digestive tract preceding the intestine; it receives food to be digested.

gonad gonad Each of the two glands located in each arm, producing gametes (spermatozoids or ovules) Each of the two glands located in each arm, producing gametes (spermatozoids or ovules)

depending on the sex of the starfish. depending on the sex of the starfish.

pyloric cecum pyloric cecum Radiated duct of the digestive tract producing digestive enzymes and also allowing digested food to Radiated duct of the digestive tract producing digestive enzymes and also allowing digested food to

be stored. be stored.

gonopore gonopore Dorsal opening through which gametes (spermatozoids and ovules) are expelled into the water to be Dorsal opening through which gametes (spermatozoids and ovules) are expelled into the water to be

fertilized. fertilized.

intestine intestine Section of the digestive tract between the stomach and the anus where absorption of nutrients is Section of the digestive tract between the stomach and the anus where absorption of nutrients is

carried out and waste is transformed into fecal matter. carried out and waste is transformed into fecal matter.

radial canal radial canal Canal running the length of the arm; it receives water from the annular canal, which then passed into Canal running the length of the arm; it receives water from the annular canal, which then passed into

the tube feet. the tube feet.

ampulla ampulla Bulb that contracts to let water enter the tube foot, allowing it to extend; when it dilates, the foot Bulb that contracts to let water enter the tube foot, allowing it to extend; when it dilates, the foot

retracts. retracts.

esophagus esophagus Muscular membranous channel of the anterior section of the digestive tract; it allows food to reach Muscular membranous channel of the anterior section of the digestive tract; it allows food to reach

the stomach. the stomach.

mouth mouth Anterior cavity of the digestive tract located on the ventral surface that allows food to be ingested. Anterior cavity of the digestive tract located on the ventral surface that allows food to be ingested.