Lab Assignment of the Week – Phylum Echinodermata and Early Chordata
A. Class Ophiuroidea (Brittle Stars and Basket Stars)
Define Autotomy. Can you think of other type of organisms that have this ability? How do brittle stars
differ from sea stars?
B. Class Asteroidea (Sea Stars)
I.
II.
Draw a sea star and label the following external and internal characteristics: Arms,
madreporite, central disk, ambulacral grooves, spines, mouth, and tube feet.
Rearrange the following structures from when water enters the vascular system to when it
leaves it:
Lateral canal, madreporite, ampulla, ring canal, tube feet, lateral canal, stone canal, and ambulacral
canal.
III.
What difference is there between the symmetry type of a larva and an adult sea star.
C. Class Echinoidea (Sea Urchins and Sand Dollars)
Observe and locate the Aristotle’s lantern in a sea urchin’s exoskeleton.
D. Class Crinoidea (Feather Stars and Sea Lilies)
What difference is/are there between a feather star and a sea lily?
E. Class Holothuroidea (Sea Cucumbers)
Dissection
Identify, draw, and label: respiratory tree, tentacles, mouth, pharynx, esophagus, dermis,
longitudinal muscles, cloaca, ampullae, tube feet (opposite side of ampullae; external
structures) and gonad.
What purpose do the tube feet serve in sea cucumbers alike the rest of echinoderms?
F. Phylum Chordata, Subphylum Urochordata
Which structures are present in the larva but not in the adult tunicate?
G. Phylum Chordata, Subphylum Cephalochordata
Observe a slide of a lancelet (Amphioxus sp.), label, and state the function of each 5
characteristics shared by chordates.