Adapted to estuarine environments, the longjaw mudsucker has evolved to survive short periods out of water, utilizing tidal mudflats and sloughs as its primary habitat.

[3] G. mirabilis also has two dorsal fins, a relatively heavy body, and a coloration that ranges from dark brown to olive on the back and sides, with a yellowish hue on the belly.

[2] As the common name suggests, the upper jaw of Gillichthys mirabilis is exceptionally long, with the maxilla reaching nearly the opercular opening in fully grown adults.

Their reproductive strategy and rapid growth enable longjaw mudsuckers to maintain stable populations in dynamic environments such as shallow sloughs, tidal mudflats, and estuaries.

[6] Their diet includes a wide range of prey they find in the mud, primarily invertebrates, though they may also consume small fish such as the California killifish.

Unlike the longjaw mudsucker, which primarily inhabits estuarine environments, the yellowfin goby can be found in fresh, brackish, and marine waters.

Additionally, yellowfin gobies are distinguished by the arrangement of pores, spines, and rays on their dorsal fins, as well as specific patterns of scales and papillae on the head and face.

[13] The yellowfin goby was introduced to California in the 1960s, primarily in the San Francisco Bay-Delta area, likely due to various practices, including its use as baitfish, similar to the longjaw mudsucker.

[16] The longjaw mudsucker (Gillichthys mirabilis) is currently listed as "Least Concern" by the International Union for Conservation of Nature (IUCN), indicating that the species is not at immediate risk of extinction.

Variations in sea levels, primarily driven by glacial cycles, have altered the availability of estuarine habitats, leading to periods of population isolation and recolonization.