Distaplia occidentalis Bancroft, 1899
Common name(s): Mushroom ascidian
|Distaplia occidentalis from about 20 m depth, Sares Head, WA. The attachment stalk is at the bottom.|
|(Photo by: Dave Cowles, July 2006)|
How to Distinguish from Similar Species: Several species of similar shape are often sand-encrusted and have 5 or more rows of stigmata. Distaplia smithi, which lives on the open coast, is a cluster of leaflike lobes. Of the other common, smooth orange local tunicates, Metandrocarpa taylori is a social ascidian in which individuals live near each other and are often connected with narrow stolons or sheets of tunic but are not enclosed within the same lump of tunic. Cnemidocarpa finmarkiensis is a solitary tunicate with a very smooth, shiny tunic.
Geographical Range: Vancouver Island, Canada to San Diego, CA
Depth Range: Intertidal to 15 m
Habitat: Protected floats and pilings, subtidal on rocks with good current, among surfgrass roots, open coast.
Biology/Natural History: Spawns April
to late August. Each zooid produces 2-4 sausage-shaped eggs, which
are retained in a brood pouch of the atrial cavity until the tadpole larva
stage. Larve are released mainly in the morning. Hermaphroditic.
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Johnson and Snook, 1955
Morris et al., 1980
Watanabe, H. and C.C. Lambert, 1973. Larva release in response to light by the compound ascidians Distaplia occidentalis and Metandrocarpa taylori. Biological Bulletin 144: 556-566
Each individual has its own separate incurrent (oral) siphon but the excurrent (buccal) siphon is shared by several adjacent individuals. This closeup shows the arrangement of individuals.