Tonicella lineata
From ize
Tonicella lineata is a mollusc known as the Lined Chiton. They are common on both east and west coasts of the North Pacific Ocean in intertidal zones.
| Taxonomy | |
|---|---|
| Kingdom: Animalia | |
| Phylum: Mollusca | |
| Class: Polyplacophora | |
| Order: Neoloricata | |
| Family: Lepidochitonidae | |
| Genus: Tonicella | |
| Species: T. lineata (Wood, 1815) |
Contents |
Range and Habitat
This chiton can be found in Japan and Siberia to North Alaska and Southern California in intertidal regions down to 90 m depths. In Puget Sound they can be found on floats or in the intertidal and littoral zones. It lives in marine and estuarine environments.
Size
Up to 5 cm long, 1.5 cm wide.
Morphology/Description
A benthic chiton. Tonicella lineata has 8 visible plates (valves) on the dorsal side and a smooth granular girdle-the band of visible tissue surrounding the 8 valves. Valves will commonly have wavy or zig-zagging patterns of lines from the edges of valves 2-7 to halfway to the middle of each valve. These lines do not cross the center of the valves. Wavy lines also appear on valves 1 and 8, but these occur across the whole of each valve in an arching pattern. Lines that occur may be many colors including white, yellow, pink, purple, and or other bright colors. The lines and color patterns on T. lineata are often similar to their habitat. The dorsal surface of the girdle will appear smooth as a solid color with splotches of a different color. Common colors are green, red, pink orange and brown. On the ventral side the girdle encircles the foot, mouth, and ctenidia.
Life History
This chiton is dioecious and reproduces by releasing gametes outside into the water where fertilization takes place. During the larval stage it will settle on the substrate near or on coralline algae and begin metamorphosis from a larva to the typical chiton bauplan.
Natural History
Tonicella lineata is an omnivorous grazer. It feeds on the superficial layers of coralline algae (Lithothanmnium) and bryozoans. Tonicella lineata has a mouth to anus digestive tract with a complete gut. Food is gleaned or scraped into the buccal cavity with its radula. Tonicella lineata will take in water at the anterior and lateral portions of the mantle and this water will pass through the mantle cavity where the ctenidia (gills) lay in the pallial grooves surrounding the foot. Gas exchange takes place here as well as waste removal when the water passes the anus and flows out the back side of the mantle with feces.
Locomotion
A wide foot is present on the ventral side of the the chiton and it uses muscular contractions to slowly move forward. Also, since this species lives in littoral zones, it will sometimes seal itself to the substrate with its girdle and arch its inner margin to create a small vacuum for better adhesion. If knocked from its place, the chiton will contract into a ball similar to many isopods in order to protect its vulnerable ventral side.
Predators
Dermasterias imbricata (Leather Star), Pisaster orchraceus (Purple Sea Star), Leptasterias haxactis (Six Rayed Sea Star), Histrionicus histrionicus (Harlequin Duck), and Lontra canadensis (River Otter).
Misidentification
Tonicella undocaerulea (Blue-line chiton), this chiton has predominately blue lines and a more pronounced zig-zag pattern. Tonicella insignis (Reeve,1847)(White-line chiton) retains the zig-zag pattern in concentric rings on the first and eighth valve and also the lines are most often white.
Links
Alaska Fisheries Science Center [1]
Berkeley Photos of T. lineata (They are extremely varied in coloration) [2]
Suggested Reading and Citations
Kozloff, Eugene N. Marine Invertebrates of the Pacific Northwest University of Washington Press, Seattle and London 1996
Kozloff, Eugene N. Seashore Life of the Northern Pacific Coast University of Washington Press, Seattle and London 1973
Lamb, Andy & Handy, Bernard P. Marine Life of the Pacific Northwest Harbour Publishing 2005
Brusca, Richard C. & Brusca, Gary J. Invertebrates Sinauer Associates, Inc., Publishers Sunderland, Massachusetts 2003
http://www.springerlink.com/content/k4h6whw1u6863003/ - Abstract from Marine Biology Journal Volume 20 Number 3, The larval settling response of the lined chiton Tonicella lineata, J. R. Barnes and J. J. Gonor.
