Exercise 21 - Deuterostomes

STUDENT OBJECTIVE

Students study the anatomy of a sea star, a tunicate, amphioxus, and perch.

EQUIPMENT AMOUNT (Class of 24 with 8 groups)
Compound microscope 1/student
Dissecting microscope 1/student


MATERIALS

Dissection pan 24/lab
Dissection instruments: scissors, forceps, blunt probe,
                          razor blades (2) or scalpel, pins24 sets/lab
Slides 2/student
Lens tissue 1 pkg/lab
Coverslips, #1 medium square 1 box/lab
Preserved specimens
  Sea star (CBS#P331D)* 1/student
  Demonstration Echinoderm Collection (CBS#P385)* 1/lab
  Demonstration Tunicate Collection (CBS#P1204F)* 1/lab
  Demonstration Amphioxus (CBS#1250C)* 1/student
  Perch (CBS#P1410KD)* 1/student
Prepared slides
  Sea star arm, cross section (CBS#Z1145)* 1/student
  Sea star pedicellaria (CBS#Z1135)* 1/student
  Ascidian tadpole larva, whole mount (Turtox #Z4.11)* 1/student
  Branchiostoma (amphioxus), whole mount (CBS#Z2705)* 1/student
  Branchiostoma (amphioxus), cross section (CBS#Z2735)* 1/student

PREPARATION

Six to Eight Weeks before Lab

If prepared slides are not on hand, an order should be placed for immediate delivery. All preserved specimens should also be ordered at this time. Upon arrival, they should be checked for useability in the lab. Any poorly stained and/or poorly prepared slide should be returned.

One Week before Lab

Check to see that dissection equipment is complete and instruments are sharp.

CLASSROOM SUGGESTIONS

Students can share microscope slides, reducing the number that must be purchased.
     This exercise is enhanced if slides, films, or filmloops on diversity are shown at the conclusion of the lab. A slide show on diversity can be run continuously during the day in a hallway showcase using a rear projection, automatic projector (Caramate). Or, if the library has a media center, a tape-slide show can be on reserve for out-of-class viewing.

ANSWERS TO CRITICAL THINKING QUESTIONS

  1. Echinoderms lack a bilaterally symmetrical, mobile adult stage (adult motility is at best sluggish), cephalization, specialized sense organs and segmentation. As well, the circulatory system is poorly developed and the nervous system is rudimentary. Gametes are shed into the water where fertilization is random.

  2. Both are elongated organisms adapted for swimming. Both possess a notochord and a dorsal nerve cord.

SUPPLEMENTAL MATERIALS

Bio Sci II, videodisc--contains images of these animals. Dubuque, IA: Wm. C. Brown Publishers. See appendix.

Chordate Evolution, slide set. West Los Angeles, CA: Science Software Systems, Inc. #200-0940

Intermediate Invertebrates, audio filmstrip. Rochester, NY: Ward's. #70W6415

Introduction to the Echinoderms, slide set. Rochester, NY: Ward's. #175W-0553

Starfish Development, 10-minute film. West Los Angeles, CA: Science Software Systems, Inc. #100-0045

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