Halocynthia igaboja Oka, 1906

Common name(s): Bristly tunicate, spiny sea squirt, sea hedgehog

Synonyms:  Halocynthia hispida, Halocynthia hilgendorfi, Halocynthia hilgendorfi igaboja, Halocynthia okai, Pyura okai, Tethyum igaboja Halocynthia igaboja
Phylum Chordata 
Subphylum Urochordata 
Order Stolidobranchia 
Family Pyuridae 
Halocynthia igaboja, found subtidally off Northwest Island.  Diameter about 7 cm.
(Photo by:  Dave Cowles, August 2009)
Description:   This solitary, non-stalked tunicate has an opaque tunic which is covered with branched, spinelike projections. The largest projections have circles of recurved branches on them, and they are so numerous that they almost completely obscure the rest of the tunic. Dark brown tunic often with red or orange siphons.  Up to about 10 cm tall and 2-5 cm across (one of the largest tunicates on our coast).  The oral siphons have 12-50 tentacles.  The atrial siphon is 1/3 to 1/2 of the way back along the body.  Siphons form a cross shape when closed but may be hard to see.

How to Distinguish from Similar Species:  Boltenia echinata has fewer projections which do not obscure the rest of the tunic and grows only to about 4 cm tall.  Halycynthia aurantium is a barrel-shaped, smooth or slightly wrinkled peach-colored tunicate that does not have spinelike projections and is attached to the substrate by a narrow stalklike region.

Geographical Range: Alaska to southern California (rare intertidally in California); Japan and Asian mainland.

Depth Range:  Very low intertidal to 165 m

Habitat:  Rock or gravel, usually near current

Biology/Natural History:   The spines often accumulate diatoms and debris.  If the current is not strong, this species may become so heavily silted that it is almost unrecognizable.  Gonads may be fertile in May.  Eggs are shed, not brooded.  The tadpole larvae are about 2 mm long.

This species contains 175 ppm vanadium in the body (not the tunic).

The pea crab Pinnotheres pugettensis sometimes lives symbiotically within the tunic, the copepod Doropygopsis longicauda may be found in the branchial chamber, and the bryozoan Celleporella hyalina may encrust the spines.



Dichotomous Keys:
  Carlton, 2007
  Kozloff, 1987, 1996

General References:
  Harbo, 1999
  Lamb and Hanby, 2005
  Morris et al., 1980 (As Halocynthia hilgendorfi igaboja)
  O'Clair and O'Clair, 1998

Scientific Articles:

Web sites:

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

Authors and Editors of Page:
Dave Cowles (2009):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)