| Bony Fishes |
Unarmored Threespine Stickleback
Gasterosteus aculeatus williamsoni
| Conservation Status: Endangered
- Courtesy of California EPA
The unarmored threespine stickleback is one of several subspecies of Gasterosteus aculeatus in the family Gasterosteidae. First described in 1854, it has been the object of comprehensive studies in an effort to properly relate it to other subspecies. Always limited in distribution to a small area of Southern California, it is of special interest because encroachment on its habitat has substantially reduced its numbers and it is in danger of becoming extinct.
Facts and Features
- Geographic Distribution
Limited mostly to the northwestern area of Los Angeles County, one small area in Santa Barbara County, and a small, isolated, introduced population in San Felipe Creek in San Diego County. Once common throughout the Los Angeles, California basin.
- Amazing Facts
Although the unarmored threespine stickleback has some of the characteristics of threespine sticklebacks, it is noticeably different from other subspecies in several ways. The most important are that the dorsal and pelvic spines are substantially shorter and most specimens either completely lack or have very few scales or lateral plates, thus the name “unarmored.”
- At the Aquarium
The unarmored threespine stickleback is illustrated on The Wave’s mosaic tile mural, Rios de la Vida (Rivers of Life). The fountain, mural and accompanying graphics illustrate the story of our Los Angeles and San Gabriel Rivers. Although not on exhibit in the Aquarium, this fish is included in our website animal database to expand on the information touched on in The Wave Fountain exhibit.