The Amazing Starfish 

Doris Agbefe                   South Shore Community Academy High School 
                               7630 S. Constance Ave. 
                               Chicago IL 60640 
                               312-535-6190

Objective:

The main objective of this mini-teach is to familiarize the students with the 
amazingly simple but complex characteristics of an Echinoderm.  This lesson is 
geared towards students at the Jr. High-10th grade with slight modifications 
made as necessary.  The lesson is intended to be taught with the assumption that 
several lessons have been covered on the Starfish. 

Materials needed: 
 
1. Preserved specimen of a Starfish
2. Modeling Clay
3. Straws
4. Rubber tubing 

Strategy:

Paper is handed out to each student at the beginning of this mini-teach.  They 
are given an opportunity to answer the question, "Are Starfish Simple or 
Complex?"   This should take about 15 mins.  The paper is handed in to the 
teacher. Students are given a brief review of what they learned in previous 
lessons. Teacher writes on the board the words: Sea Urchin, Sea Star, Sand 
Dollar, Sea Cumber.  Students are asked the question, "What do these organisms 
have in common?"  Students are to answer that these organisms belong to the 
Phylum Echinodermata.  Students are also lectured on a brief review of the organ 
systems that are present in the Starfish.  Special emphasis is placed on the 
Water Vascular System which is a vital component of some Echinoderms.  This 
system is used for locomotion and food getting.  Special emphasis is also placed 
on the body organization of Starfish.  The definition of symmetry is given.  
Pentaradial symmetry is discussed because this is a type of symmetry that some 
Echinoderms exhibit. 

Performance Assessment:

Students are to construct a figure with the modeling clay that resembles the 
components essential to the water vascular system.  Step 1: Students take clay 
and make a round flat patty.  (This is analogous to the ring canal that is 
present in Starfish.)  Step 2: Students take 5 cut straw sections and place 
around clay patty.  (This is analogous to the radial canals that are present in 
each arm of the starfish.)  An explanation is given on how water enters the 
starfish and ultimately causes movement.  Students assemble themselves in groups 
of five in a circle to illustrate the concept of pentaradial symmetry.  Each 
student in the circle represents 1 of the 5 arms present in the Starfish.  Paper 
is passed out.  Students are now asked to answer the question once again, "Are 
Starfish simple or complex?"  The paper is handed in to the teacher.  The 
teacher evaluates the two answers noting if there is any change. 

Multicultural Aspect:

American schools are a great mix of students from various cultures.  Jacques 
Loeb was a German American physiologist who studied sea urchin eggs.  He was
particularly interested in the concept of parthenogenesis.  Parthenogenesis is
the reproduction of organism without the fusion of gametes of opposite sex.
Explain what happens with bees.

Reference:

Encyclopedia of Marine Invertebrates.  Jerry Walls, ed. 1982, TFH Publications
Inc.