Life Cycle - Organisms (4B)

  • Classifying invertebrates.
  • Comparing invertebrates.
  • Arthropoda
  • Cnidaria
  • Echinodermata
  • Mollusca
  • Porifera

Students look at different invertebrates and try and determine how they are similar.


There are five phyla represented in this lab: Porifera, Cnidaria, Arthropoda, Mollusca, and Echinodermata. The students should discover the characteristics described below. After the lab is completed discuss the following characteristics.

PORIFERA (SPONGE): This soft, porous specimen represents a very primitive invertebrate. Sponges that are used today for cleaning are synthetic. However, if you look at a synthetic sponge, you notice that it looks like a real sponge. In the early days, people used sponges for soaking up water.

Water containing nutrients, enters pores of sponges. Waste is released through larger openings called "oscula." Look for the different size openings on the specimens.

CNIDARIA (CORAL): Cnidaria are organisms with a central stomach surrounded by stinging cells on the end of finger-like projections. This phylum includes jellyfish, sea anemones, and corals. Coral heads are the skeletal remains of living corals. They are rough in texture and come in a variety of shapes, sizes, and colors. Corals are classified as soft and hard corals. The coral samples you see have tiny holes which once contained a single organism.

Examples from this phylum have holes, rough textures, radiating walls or branches, and are mostly white when dead. Coral may form large reefs, like the Great Barrier Reef in Australia, which serve as homes and shelters for fish and other sealife.

MOLLUSCA (CLAM, MUSSEL, SCALLOP, SNAIL): Specimens from this group of invertebrates have hard shells, curved or twisted bodies, one or two shell parts, and an unsegmented body. Many animals from this phylum can be found at stores or seafood restaurants as clam chowder, seafood platters, or escargot.

ECHINODERMATA (SEA COOKIE, SEASTAR, SEA URCHIN): This phylum consists of animals that have a 5-arm pattern, sometimes brittle bodies, and circular holes that allow the entrance and removal of food and waste. One example, the familiar seastar, can grow back body parts that are cut off or lost.

ARTHROPODA (BARNACLE): This phylum consists of segmented or jointed invertebrates including insects, spiders, and crustacea. A barnacle is a shrimp-like arthropod with a shell. Students will not be able to see the arthropod itself, only the shell that houses the organism when it is alive.


  1. Students will examine specimens of invertebrates in this lab activity. Invertebrates are animals that lack a backbone and comprise 95% of the Animal Kingdom. Discuss techniques on observing the specimens using the senses of touch, sound, and sight.
  2. Students should  determine which samples belong together by describing characteristics such as texture, shape, growth patterns, hardness, and color. Each of the specimens is an individual species. Emphasize with students that there are many other species within these groups.

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