The Amazing Starfish 

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


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


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.


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