Thalia democratica
Forskål (1775)
Download a fact sheet for Thalia democratica (PDF 378KB)
Taxonomy
| Phylum | Chordata |
| Class | Thaliacea |
| Order | Salpida |
| Family | Salpidae |
| Genus | Thalia |
| Species | democratica |
Size
- Aggregate form 1.8 - 18.2 mm
- Solitary form 2.3 - 11.7 mm (without process)
Distinguishing characteristics
Aggregate form
Body
- Oval
- Anterior end of body rounded, tapering to a pointed or rounded terminal process
- Test thick, bluntly pentagonal
- Atrial opening not central
- Posterior lateral protuberance on one side only
- Slight asymmetry
- Variable number of tubular process from mantle to test
Muscles
- 5 continuous body muscles
- M1-M3 and M4-M5 fused mid dorsally for short distance
- The two groups of muscle bands are separate dorsally
- Muscle structure similar to other Thalia aggregates, species differentiated by shape of body and projections
Gut
- More compact than in solitary form
- Endostyle confined to anterior half of body
- Nucleus has posterior projection (may not be visible)
Solitary form
Body
- Smooth test
- Lateral projections simple and not bifurcated
- All test projections are echinate
Muscles
- 5 body muscles in complete rings
- M5 may be narrowly interrupted ventrally
- M1-M3 and M4-M5 fused mid-dorsally over short distance
- Muscle structure similar to other Thalia solitarys, T. democratica differentiated by non bifurcated lateral projections
Gut
- Stomach partly extends into middle posterior projection
- Distribution
- Cosmopolitan, eurythermic species from warmer waters. Globally between 60°N - 40°S
Ecology
References
- Godeaux, J. E. A. (1998). The relationships and systematics of the Thaliacea, with keys for identification.
- Thompson, H. (1948). Pelagic tunicates of Australia, CSIRO, Melbourne, Australia.
- Van Couwelaar, M. (2003). Zooplankton and micronekton of the North Sea. Expert Center for Taxonomic Identification, Amsterdam.