Weeks 13, 14:Mollusa and Beaches

Weeks 13, 14: Mollusca and beaches

We have two weeks to study this varied and fascinating phylum! Also, shells and beaches go hand in hand and so beaches are the oceanography topic we will be studying during this unit.


Your reading for this unit is chapter 10 and it is a long one with lots of great information, so you will want to take it in chunks. I suggest you break it down in the following manner:

  • Introductory materials pp 95-98: focus on taxonomy, shell formation, and feeding methods. Compare bivalve and gastropod life cycles. This section could be done over a couple of days time.
  • Gastropods pp 99-111: take a look at the anatomy on p 99, especially focusing on the external anatomy terminology as it will help you in your shell collection identifications.Then read through and familiarize yourself with the various types of gastropods (including nudibranchs and sea hares). You could very well take several days on this section.
  • Chitons p112: this is a short read and can be fit in easily any time.
  • Bivalvia pp113-121:Check out the interesting anatomy on p113, then familiarize yourself with the various types of bivalves on pp114-121. Take a couple of days on this section as well.
  • Cephalopoda 122-124:One page of introductory material and then a page each for squid and octopi make for an easy day’s study.


1. Check out your local field guides and go see what you can find! Make an earnest attempt to observe some living specimins if at all possible. Make notes and sketches in your lab notebook.

2. Watch the short online film: Killer clams.

3. If you like, this would be a great time to do a clam dissection. Gather a clam from your beach or buy a preserved specimen from a supplier such as Carolina Biological. An online dissection guide can be found here:Clam dissection. (If you do not wish to dissect a clam yourself, just looking over the online guide is very informative as well.)

Beach Features:

For beach study we will be using the book ” Florida’s Living Beaches: A guide for the curious beachcomber” by Blair and Dawn Witherington. This book has an excellent and thorough section on beach features including:

  • basic beach anatomy
  • dunes
  • salt pruning
  • wrack lines
  • beach cusps and scarps,
  • sand ripples
  • dark sands and shell hash
  • swash and backwash
  • sea foam
  • sand erosion, sand accretion
  • sandbars
  • ridges and runnels
  • effects of tides, waves and surf
  • nearshore currents, offshore currents
  • beach weather, hurricanes and other storms
  • red tide
  • inlets and passes
  • barrier islands, and
  • the beach at night.

If you cannot find this book, try to find another which covers similar topics or try this wikipedia article or  this website , which has a lot of good info and pictures of beach features and different types of beaches.

(fyi: if you live in Florida, we have found the above book to be the absolute best guide to identifying everything from shells, birds, plants, seaweeds, minerals, seabeans, and everything else we find on our beaches. Just an excellent book overall and highly recommended.)

Here is a short YouTube clip about changes in Beach Morphology due to a hurricane.Beach Morphology before and after a hurricane.


1. Head to some beaches and identify as many features as you can. Take a photo of your local beach, print it up and label the parts. Stick it into your notebook. Alternatively, find photos of several different kinds of beaches online and do the same.

2. Don’t forget about your shell collection!!!! It is due before Christmas break!



  1. I’ve just posted a blog on websites that were helpful for detailed gastropod study – specifically nudibranch and squid.


    • Great! Thanks!

  2. A couple of mollosca links we may use:
    Comparison Chart http://www.biologycorner.com/worksheets/mollusk_chart.html
    Squid dissection http://www.blackspvbiology.50megs.com/squid.dissect.html and http://preuss.ucsd.edu/FacultyWebpages/Solomon/HSHandouts/Squid%20Lab.pdf
    And a webquest http://can-do.com/uci/lessons98/Squid.html
    An activity for elementary kids on how Cephalopoda move through the water http://www.abc.net.au/science/surfingscientist/pdf/lesson_2_diving_octopus_student_worksheet.pdf

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