Life Cycle - Organisms (3A)

  • Learning about different marine invertebrates.
  • Comparing and contrasting their similarities.
  • barnacle
  • bivalve
  • coral
  • gastropod
  • mollusk
  • sand dollar
  • sea urchin
  • sponge

Students examine sea life specimens.


The best way for students to learn about invertebrates is to touch, observe, and record information about each group. Below is some background information on each of the organisms that the students will look at in lab.

SPONGE: The sponge is a very primitive organism. It has no organs nor tissues. It is basically a group of cells that live together. If you strain a sponge in a sieve, it will come back together. Have the students look at the pores, which are used to obtain nutrients by the sponge. Remind students that this is an animal and the sponges that you buy in the store today are usually artificial.

CORAL: Coral belong to a family that include jellyfish. The sample is the skeleton of a once living organism. You may want to show the students pictures of what real coral looks like. Each hole on the skeleton represents one coral; corals live together in  what is called a colony. Corals have primitive organs of digestive system and nervous system.

BARNACLE: The skeleton represents an outer covering of a living shrimp-like organism. The skeleton will adhere itself onto a surface and the animal will live there. Barnacles have a digestive, nervous, and circulatory system, but are relatively primitive. They belong to the largest grouping of invertebrates, the arthropods.

MOLLUSCA: Mollusks are usually familiar to students. Most students have seen snails and clams. Mollusks have developed organs and are very abundant in a normal seashore environment. Included are bivalves (2 shells) and gastropods (1 shell).

SEA COOKIE  AND SEA URCHIN: Sea cookies belong to a family that is more advanced compared to other invertebrates called echinoderms. Sea stars and sand dollars all belong to this group. Notice the 5 part symmetry.


  1. Give students the packet of organisms and identify the different organisms. However, do not say much about them. You may want to give them some clues of descriptive words to help them along like holes, spiral, etc.
  2. After they finish describing each, go over them as a class. Use the information on each group to provide the students with more information.

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