Chiton tuberculatus« Chiton tuberculatus Linné, 1758

The CHITONS, or Coat of Mail shells are an unusual form of mollusk with a fleshy girdle that envelops and holds eight shelly plates, or valves firmly in place. Chitons are classified in the Order Polyplacophora. More than 800 species are grouped into approximately 10 Families, depending on which classification you subscribe to.

Most Chitons live in intertidal zones, but some species dwell in rather deep water. Chitons are distributed in all oceans from the polar regions through the tropics. The greatest concentration of species, though, is along the west coast of North America and in Australia, where at least 50 percent of the know species are found. Unlike many of the drab-colored, cold-water gastropods and bivalves, Chitons often exhibit beautiful colors and striking patterns in these cold regions. An outstanding characteristic of Chitons is the variability of color and pattern that can be exhibited by one species. The polymorphic nature of many Chitons has made the group a growing favorite of collectors. Displaying a series of color forms can elicit a gasp of "wow" from even the most staid individuals. It is a rarity to find a Chiton with only 7 valves instead of the typical 8, and even more unusual is one with 9 valves. Chitons that have aberrant numbers of valves are highly prized by collectors and command very high prices. Another rarity are Chiton hybrids. I know of one Chiton population that hybridizes, and I suspect that others may eventually be found.

Two important factors to be considered when preparing chitons for a collection. First, a Chiton must be properly collected, and secondly, undergo a special preservation process that will prevent it from curling up into a permanent pillbug-like ball. When properly collected and preserved, Chitons will last a lifetime in a collection. Preserving Chitons Flat as a Board, is an article that will take you step-by-step through the process of Chiton preservation. It is available to read here on The article first appeared in Volume 26, No. 2-3 (1991) of "Thatcheria", newsletter of the Chicago Shell Club.

Keeping the girdle intact for display is far more desirable than having a specimen with disarticulated valves. Chiton girdles are, in many cases, as fascinating as the often beautifully ornamented valves. Some girdles have snakeskin-like scales, or are covered with shaggy hairs. Others have sharp spicules of varying length.

LITERATURE: There exists a significant body of literature dealing with the Chitons. Many though, are papers published in scientific journals such as an important series of revisions to various Chiton Families and Genera, as well as geographical treatments, authored by the late Antonio J. Ferreira in The Veliger
, A quarterly scientific journal published by the California Malacozoological Society.    Recently, publication of Chitons of the World - An illustrated synopsis of Recent Polyplacophora by Frans J.A. Slieker (160 pages, hardcover. L''Informatore Piceno, Ancona, Italy. ISBN:8886070055 - 2000) has brought together the large body of scientific literature on Chitons into one popular tome. More than 500 species are covered and illustrated in color, with illustrations of 61 type specimens. The book arranges the species by faunal provinces, helping narrow down the identification of well-documented specimens. This is an important publication recommended for anyone interested in collecting and identifying Chitons. Living Chitons from the Mediterranean Sea by Dell'Angelo & Smriglio is the most complete publication dealing with the Mediterranean Chitons. The 256 page book contains a wealth of information on all of the known Chiton species from this region. Catalogue of the Living Chitons (Mollusca, Polyplacophora) (1998. Second, revised edition. 204 pages) by Kaas and Van Belle (Universal Book Services/Dr. W. Backhuys, Rotterdam) is a checklist of Chiton species, each with an original citation and current classification. This important work has been expanded upon by Kaas and Van Belle in Monograph of Living Chitons (E.J. Brill, Leiden; New York; Koln), a planned 10-volume definitive work on the Chitons. The first volume appeared in 1985, and to date five volumes have been published. The treatise is rather scientific and uses high-quality line drawings instead of photographs to illustrate the species. Long out-of-print, but important regional literature dealing with the Polyplacophora are, A Monograph of the Australian Loricates Iredale, T. & A.F.B. Hull (1927. Royal Zoological Society of New South Wales, Sydney), South Australian Mollusca: Chitons, Bernard C. Cotton (1964, p.151, Govt. Printer, Adelaide), and A Collector's Guide to West Coast Chitons, Burghardt & Burghardt (1969. Special Publication No. 4, San Francisco Aquarium Society, Inc.). The classic antiquariun work on worldwide Chitons is Pilsbry, H.A., Manual of Conchology, Polyplacophora, Volumes XIV & XV (1892/1893. Academy Natural Sciences, Philadelphia.). These two volumes are part of a larger series of monographs on marine and land mollusks. They are next to impossible to obtain, but worth seeking out.   Many other current and out-of-print titles, too numerous to list here, can be found by perusing price lists of natural history book sellers on the Internet.
Open List   Close List
The Quick Links list can be moved by clicking and holding the mouse-pointer on the top of the list.

Common Chitons of Alaska - NOAA- PDF Poster
Chitons - Oregon to S.E. Alaska
Chitons Fauna of Bali - by Enrico Schwabe - a slide show here on
Chitons (Polyplacophora): Molluscs - Links to images
Conchiglie del Mediterraneo - Polyplacophora
Conquiliologistas do Brasil - Ischnochitonidae
Doug Eernisse - Chiton Images on the Web
Polyplacophora Of N.American Pacific Coast Alaska to Baja California Norte - R.Clark
Gulf of Eilat (Aqaba) Polyplacophora Species
Micro Shells - Polyplacophora
Victorian Intertidal Marine Life - Chitons


Animal Diversity Web - Polyplacophora
Illustrated Keys to the chitons - A. Baldwin [PDF document]
Learning About Chitons
Polyplacophora - Animal Diversity Web
The Polyplacophora - U.C. Museum Paleontology
Class Polyplacophora
Search - Enter search name, word, or locality, e.g. Conus, literature, or Florida. Avoid using the word "shell" -
e.g., use Cone instead of Cone shell.


The illustrated Chitons are from private, or museum collections.
Click on the thumbnail images for an enlarged view. Images will open up in a separate, resizeable window.
top of page
Polyplacophora (Chiton) Classification




[Classification based on in part: Parker, S. P. (ed.), 1982: Synopsis and classification of living organisms. Vols. 1 & 2. McGrew-Hill Book Company]

[Double-click background to return to the Subfamily menu]
Polyplacophora Suborders & Families

  • Family Hanleyidae
  • Family Choriplacidae
  • Family Lepidopleuridae
  • Family Subterenochitonidae
  • Family Ischnochitonidae
  • Family Schizoplacidae
  • Family Callochitonidae
  • Family Callistoplacidae
  • Family Chaetopleuridae
  • Family Mopaliidae
  • Family Schizochitonidae
  • Family Chitonidae
  • Family Acanthochitonidae
    Family: HANLEYIDAE back to menutop of page
    Family: CHORIPLACIDAE back to menutop of page
    Family: LEPIDOPLEURIDAE back to menutop of page
    Family: SUBTERENOCHITONIDAE back to menutop of page
    Family: ISCHNOCHITONIDAE back to menutop of page
    WI-0104Callochiton castaneus (Wood) - South Africa, 21mm. WI-0109Ceratozona squalida (C.B. Adams) - Puerto Rico, 25mm. WI-0160Ischnochiton lineolatus Blainville - Australia, 35mm.
    WI-0135Lepidochitona lowei (Pilsbry) - California, 20mm. WI-0130Lepidozona intersticta radians (Pilsbry) - California, 19-25mm. WI-0134Lepidozona mertensii Middendorff; - Vancouver Island, Canada, 39mm.
    WI-0159Lepidozona willetti (Berry) - Alaska, 20-25mm. WI-0147Nutallina fluxa (Carpenter) - California, 24mm. WI-0165Tonicella lineata (Wood) - Ischnochitonidae - British Columbia, Canada, 46-51mm.
    WI-0163Tonicia lamellosa (Quoy & Gaimard) - Ischnochitonidae - Western Samoa, 12-13mm.    
    Family: SCHIZOPLACIDAE back to menutop of page
    Family: CALLOCHITONIDAE back to menutop of page
    Family: CALLISTOPLACIDAE back to menutop of page
    Family: CHAETOPLEURIDAE back to menutop of page
    Family: MOPALIIDAE back to menutop of page
    EM-0101Amicula vestita (Broderip & Sowerby) - northwest Bering Sea, 46mm. EM-0123Mopalia ciliata (Sowerby) - Washington (State), 48-50mm. EM-0125Mopalia muscosa (Gould) - Washington (State), 38mm.
    EM-0124Mopalia spectabilis Cowan & Cowan - Mopaliidae - Washington (State), 63-65mm.    
    Family: SCHIZOCHITONIDAE back to menutop of page
    Family: CHITONIDAE back to menutop of page
    IC-0110Acanthopleura haddoni Winckworth - southern Sinai Peninsula, Egypt, 60mm (I didn't say all Chitons were beautiful). IC-0115Chiton discolor Souverbie - New Caledonia, 26mm. IC-0112Chiton squamosus Linné - Bahamas, 54mm.
    Chiton tuberculatus color formsChiton tuberculatus (Linné, 1758) - Puerto Rico - Two very rare color forms; an orange colored specimen, and one where the girdle lacks any markings that are so characteristic for this species.  IC-0116Chiton tuberculatus / squamosus [hybrid] - Puerto Rico, 55mm.  
    Family: ACANTHOCHITONIDAE back to menutop of page