Starfish (also known as Sea Stars)
Pre-lab
Mrs. Trotter
Vian Middle School
Not real fish
 No backbone
 No fins
Kingdom-Echinodermata
 Have spiny skins
 Usually have 5 appendages
 There are over 6,000 species
 Radially symmetrical
 Echinoderm in Greek means “spiny skin”
Symmetrical
 As larvae they are bilaterally symmetrical
 As they mature they become radially symmetrical
Endoskeleton
 Spines – with canals located inside
Ray
 Each arm is called a ray
 Usually have 5
 Has the ability to regenerate an entire organism IF is has one
whole ray and at least a piece of the central disc (very slowcould take an entire year to regenerate)
Eyespot
 Each ray of a starfish has a light sensitive organ
 You can see it by spreading the tube feet at the tip of the ray
 It can’t see like you or I
 It only detects light and the direction it is coming from
 This gives them somewhat of an idea of where they are going
Anus
 Very inconspicuous
 Located on the dorsal or upper side in the center of the disc
Mouth
 In the center on the underside or ventral side
Feet
 Hundreds of tiny feet
 Tube fee or podia
 Suckers located on the ends of feet
 Capture and hold prey (clams)
 Hold onto rocks in swift currents
How to dissect the specimen
 The dissection