University of Iowa
Evolution & the History of Life

Lab 5
Colonial Invertebrates


Part II. Phylum Cnidaria (Coelenterata)

Class: Anthozoa (Corals)

A. Read about cnidarians.



B. Look at the diagrams of the polyp and medusa below: use the list of terms and the reading, linked above, to make sure you understand the labelled parts.
Polyp Medusa

C. Look at the UC Berkeley web site for another diagram of a medusa and more information about general Cnidarian morphology.

D. Read about a group of Cnidarians, the corals.

E. Look at UC Berkeley's Cnidaria in the fossil record web site.

There are two types (Orders) of coral you will look at in this section of the lab: rugose coral and tabulate coral. The green box contains information about rugose coral. You will need to use specimens from boxes 7-10 to answer the questions in this section.

F. Read about rugose corals.

G. Look at the following two diagrams of rugose corals: use the list of terms and the reading, linked above, to make sure you understand how to locate the labelled parts on a specimen and how to describe them.

   Rugose coral morphology

     Reconstruction of living rugose coral

H. Know the common features of rugose corals:

  • well developed septa
  • tabulae often present
  • occasionally, one or more undeveloped septa form a gap called the fossula
  • some are solitary and horn-shaped



    I. Look at the following links:

  • UC Berkeley's rugose corals
  • images of fossil rugose coral from the Newcastle site: image 1, image 2. Both of these images are of the same Permian horn coral: one is the side view and one is the top view.



    J. Look at the specimens from boxes 7, 8, 9 and 10:

    These specimens are from Order Rugosa (solitary or colonial, large calyx with well-developed septa). 

    Specimens in box 7 are Cyathophyllum, family Zaphrentidae.

    Question 3: Draw a transverse section of Cyanthophyllum (looking down from above, perpendicular to the central corallite axis) and label the epitheca, a septum, the calical pit, a dissepiment, and the cardinal fossula.
    • Specimens in box 8 are Charactophyllum, family Zaphrentidae.
    Question 4: List two characters which distinguish Cyanthophyllum (box 7) and Charactophyllum (box 8).
    • Specimens in box 9 are Hexagonaria, family Acervulariidae; specimens in box 10 are Lithostrotionella, family Lonsdaleiidae.

    Question 5: List two morphological differences which you can see between these two colonial rugose corals (from boxes 9 and 10).

    The second Order of corals you will look at today are the Tabulate corals. You will need to use specimens from boxes 4-6 to answer the questions in this section.

    K. Read about tabulate corals. Use the diagram below and the descriptions in the reading, linked above, to help you answer the questions.

    Be sure to open the links and look at each type of tabulate coral. This will help you answer the questions.

    L. Look at the specimens from boxes 4, 5 and 6:

    These specimens are from Phylum Coelenterata, Class Anthozoa, subclass Zoantharia, Order Tabulata. These are always colonial and have small calices with reduced septa. More specifically:

    • Box 4: Halysites, family Halysitidae
    • Box 5: Favosites, family Favositidae
    • Box 6: Syringopora, family Auloporidae
    Question 6: What type of growth form (arrangement of corallites within a colony) does each species (boxes 4, 5, & 6) have? What other characteristics distinguish these three species?
    Question 7: Draw a longitudinal section of Favosites (box 4). Label a corallite, a mural pore (small holes in the corallite wall), the theca (corallite wall), and a tabula.

    M. Find the tabulate coral in the image below:


    Want to see if you are correct? Give up? Click on the picture to reveal the location.

    N. Know the common features of tabulate corals:

    • NO septa and NO solitary horn shape
    • Well-developed tabulae
    O. Optional: Look at other coral links.

    You are finished with Part II of the lab. Choose Part I, Part III, or Part IV from the choices below, if you have not yet completed these sections.

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    Last updated on February 24, 1997-jlc.