Distaplia smithi Abbott & Trason, 1968

Common name(s): Smith's distaplia, Paddle ascidian

Synonyms: Distaplia smithi
Phylum Chordata 
Subphylum Urochordata 
Order Enterogona 
Suborder Aplousobranchia 
Family Clavelinidae 
A cluster of Distaplia smithi on a stalk of Egregia kelp at Cape Flattery.  Hydroids are clustered higher on the stalk.  Individual clusters of Distaplia smithi are about 4 cm tall.
(Photo by:  Dave Cowles, July 2010)
Description:  This compound ascidian (individual zooids live clustered together within a common tunic) grows in a cluster of paddle-shaped stalked lobes, each of which contains multiple zooids.  The pharynx has 4 rows of stigmata.  The tunic of colonies is not encrusted with sand.  Each paddle-shaped lobe of the colony is 1-5 (up to 10) cm tall and the distal blade contains 1-9 double rows of zooids.  Color from cream to orange-brown

This species was named in honor of Ralph Smith who was an early author of Light's manual.

How to Distinguish from Similar Species:  Colony shape is similar to that of Sycozoa. Distaplia occidentalis grows in club or mushroom-shaped colonies.

Geographical Range:  Prince William Sound, Alaska to Monterey Bay, CA

Depth Range:  Very low intertidal to 15 m depth.

Habitat:  Open coast on rocks.  Under ledges, on channel or cave walls in areas with surge or strong current but not direct wave shock.

Biology/Natural History:  Functional zooids occur only in the flattened blades, not in the stalks (though developing "blastozooids" can be found in the stalk).  The zooids are arranged in double-rowed "systems" primarily visible from only one side of the blade.  Zooids in a system are arranged alternately on opposite sizes of a common cloacal tube that empties out the tip of the blade.  The oldest zooids in the system are at the distal edge of the blade and the youngest are proximal.  As the colony grows old zooids may be shed from the distal end and new zooids added on the proximal end of the paddle.

Sexual reproduction occurs in the first six months of the year.  Gonads develop in January and February.  The testes develop first then later the ovaries develop.  The ripe eggs are orange.  Orange developing larvae are kept in brood pouches such as those in Distaplia occidentalis and are visible especially April-June.  Most of the tadpole larvae have been liberated by July.

In central California, some colonies contain parasitic copepods.



Dichotomous Keys:
  Carlton, 2007
  Kozloff, 1987, 1996
  Smith and Carlton, 1975

General References:
  Harbo, 1999
  Lamb and Hanby, 2005
  Morris et al., 1980

Scientific Articles:

Web sites:

General Notes and Observations:  Locations, abundances, unusual behaviors:

Authors and Editors of Page:
Dave Cowles (2010):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)

Rosario Invertebrates web site provided courtesy of Walla Walla University