The moon jellyfish Aurelia sp.1 has the largest geographic range of all species of Aurelia studied to date. It occurs, at least, in Tokyo Bay and northern Japan, in Australia, on the Atlantic and Mediterranean coasts of France, and from Los Angeles to San Diego (Dawson & Jacobs 2001; Schroth et al. 2002; Dawson 2003); it probably also exists in San Francisco Bay (Greenberg et al. 1996; Dawson & Martin 2001). Each of the other 10+ known species of moon jellyfish have more limited geographic ranges. For example, A. aurita occurs in the cold-temperate North Atlantic, A. labiata in the cold-temperate eastern North Pacific, and A. limbata in the northern polar oceans. Populations of Aurelia sp. 1 thus appear to be disjunct, while populations of other species of moon jellyfish generally are contiguous (below). Comparison of genetic variation, however, shows a very different pattern. Genetic variation in Aurelia sp.1 is smaller than genetic variation in most other species of Aurelia (Schroth et al. 2002; Dawson 2003).

The global distribution of the genus Aurelia (grey) and the known ranges of species
(colors and letters, as indicated by molecular and morphological analyses).
The ranges of most species are still poorly defined.

 

 

While there are several possible explanations for the observed contrast, such low genetic variation coupled with such a large geographic range that includes disjunct populations in some of the major warm-temperate seaports of the world suggests that Aurelia sp. 1 may be an introduced species. Notably, the latitudinal, or temperature, range over which Aurelia sp. 1 occurs is similar in each of the five major coastal regions from which it is currently known, a pattern that is commonplace in exotic species and may reflect underlying ecological processes (Sax 2001). Although its point of origin and the pattern and timing of introductions are currently unknown, wider geographic sampling and more extensive molecular analyses could clarify these issues (e.g. Holland 2000).

 

Aurelia sp.1
Japan

Aurelia sp.1
Australia