Common along Pacific Northwest Coast. Especially common in the San Jaun Islands and Strait of Jaun de Fuca (Niesen 1997).

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Occurs from Kamchatka, Russia, through the Aleutian Islands, Alaska, to southern California (O'Clair and O'Clair 1998, Field and Field 1999, Slieker 2000).

Katharina tunicata is a medium sized chiton, with an average length of 7 cm. Its black girdle almost completely covers the eight whitish plates, leaving a diamond shaped pattern down the dorsal side. The plates are sometimes overgrown with algae, so they will appear green (Mohler 1997). Like most chitons, K. tunicata is oval shaped, but when removed from the rock it will ball up (Karleskint 1998). The underside of K. tunicata is commonly peach colored,and houses the gills and mouth. The foot is surrounded by mantle and is usually darker orange.

Length: 13 cm

Katharina tunicata is found in the middle and upper zones of the rocky intertidal, and can withstand hard wave action. This chiton is often seen near the borders of mussel clumps. (Niesen 1997; Mohler 1997)

Aquatic Biomes: coastal

Comments: Intertidal to 40m (Slieker 2000). Common on rocky shores with heavy wave action (Field and Field 1999, Gallivan and Danforth 1999, Ruesink 2003), usually found on stony or rocky bottoms in the lower middle intertidal zone and the lower intertidal zone (van de Hoek 2002). In Three Saints Bay, Kodiak Island, Alaska, favored habitats were crevices on vertical rock faces between individuals of barnacle Balanus cariosus, inside dead shells and on open rock surfaces (Nybakken 1969). Unlike most other chitons, K. tunicata tolerates direct sunlight (Nybakken 1969, O'Clair and O'Clair 1998, Field and Field 1999, van de Hoek 2002).

Habitat: They attach to rocks where they are exposed to heavy wave action.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Katharina tunicata is an herbivore. Its main food sources are brown (Phaeophyta) and red (Rhodophyta) algae (Mohler 1997).

Comments: A moving grazer, diet varies regionally; eats many kinds of brown and red algae, including kelps, as well as Sea Lettuce (Ulva) and encrusting diatoms. Will also eat sponges, tiny barnacles, spirobid polychaetes and bryozoans (O'Clair and O'Clair 1998).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

>1,000,000 individuals

Comments: A common inhabitant of middle to lower intertidal zones from Kamchatka, Russia and the Aleutian Islands, Alaska to Southern California (Field and Field 1999, Kozloff 2003).

Predators include humans, sea urchins, leather stars, Black Oystercatchers, and Glaucus-winged Gulls (O'Clair and O'Clair 1998).

Kathrina tunicata, like all chitons, has seperate sexes. Katharina tunicata spawns March through July. Chitons do not copulate; instead, the male release sperm and fertilzation occurs in the sea or in the mantle trough of the female, depending upon the species. After fertilization, eggs can be shed, or are brooded in the mantle cavity of the female. This is also species-dependent. Chitons have a free swimming (trochophore) larvae which develops into the adult(Dorit 1991).

Sexual maturity at 35mm in length. Spawns in spring in the southern part of its range; during summer further north (e.g. in June on the outer coast of Vancouver Island, British Columbia). Females broadcast eggs (O'Clair and O'Clair 1998) after nearby males shed their sperm (Barr and Barr 1983). Settlement and metamorphosis can be induced by the encrusting coralline alga, Lithothamnion spp. Onset of gonadal growth in fall is triggered by declining water temperatures. Final gamete production in spring requires increasing water temperatures. Adults live to three years in California, perhaps longer in Alaska (O'Clair and O'Clair 1998).

US Federal List: no special status

CITES: no special status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Very widespread in most of Alaska to British Columbia to southern California. plus Russian distribution.

Comments: Intertidal zones may be affected by industrial activities, such as timber harvest, oil and gas development, mining, and seafood processing. Coastal development, sewage discharge, harvest of intertidal species for food, and over-visitation resulting in trampling and collecting by beachcombers are also of concern (Tindall 2004). Natural perturbations such as earthquakes and scouring incurred by major storms threaten subtidal and intertidal communities. Though little understood, the effects of global warming will likely result in changes in intertidal community structure and diversity; in California, researchers have already noted a reduction in cold-water species in intertidal communities attributed to warming water temperatures (Tindall 2004).

Biological Research Needs: Effects of subsistence harvest, trampling, and over-visitation on localized populations and community structure needs study. Research needed to examine the influence of size structure of prey and competitor species, algal production and productivity, and predation by sea otters and sea stars. Effects of global warming on species dynamics needs study. Indigenous ecological knowledge needs to be summarized for this species.

Global Protection: Very many (>40) occurrences appropriately protected and managed

Comments: In the U.S., protected under the Coastal Zone Management Act (CZMA) (USFWS 1995, NOAA 1996).

Needs: Intertidal areas receiving heavy human traffic should be conserved by restricting and/or monitoring access or regulating collections. Subsistence harvest should be monitored annually. In areas of high subsistence usage, population surveys are necessary to monitor stocks. Communication and collaboration with communities that use K. tunicata as a resource should be improved, and indigenous knowledge incorporated into management and decision making.

Comments: Complete sequencing of the mitochondrial genome of Katharina tunicata revealed a gene arrangement much closer to those of arthropods (Drosophila yakuba) than that of another mollusk, the bivalve Mytilus edulis (Boore and Brown, 1994). The arrangement of genes in Katharina mtDNA is very similar to several other metazoan phyla, which was unexpected given the marked dissimilarity in arrangement between Mytilus and Katharina and given the closer phylogenetic affinity that is thought to exist between Mytilus and Katharina (Boore and Brown, 1994). An unlikely explanation is that the assumed relationship of bivalves and chitons as taxa within the phylum Mollusca is incorrect, but the placement of bivalves within the Mollusca is strongly supported by comparative morphology, and a more plausible explanation is that rates of both substitution and rearrangement in mtDNA are or have been very different in the lineages leading to Katharina and Mytilus (Boore and Brown, 1994).