Katharina tunicata

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).

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

Occurs from Kamchatka, Russia, through the Aleutian Islands, Alaska, to southern California (O'Clair and O'Clair 1998, Field and Field 1999, Slieker 2000).

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).