Artedius fenestralis, the padded sculpin, is a species of marine ray-finned fish belonging to the family Cottidae, the typical sculpins.[1] The species is native to the eastern Pacific Ocean, with a range extending from the Alaska Peninsula to Southern California. It grows to a maximum length of 14 centimeters[2] and subsists on a diet of shrimp and small fishes.[3] A. fenestralis is commonly found in rocky intertidal and subtidal habitats, particularly near kelp forest edges.[4]
Artedius fenestralis is primarily found along the North American Pacific Coast, specifically in the Eastern Pacific, where it inhabits nearshore environments such as rocky intertidal zones and subtidal areas. This species is commonly associated with kelp forest edges, where it displays a strong habitat preference for these ecotones and contributes significantly to the structure of fish assemblages in these regions.[5] It occupies various benthic habitats, where it utilizes suction feeding to prey on small invertebrates such as amphipods and isopods.[6] This habitat selection likely supports its specific dietary needs, as these benthic environments offer a variety of prey types suitable for the species' feeding strategy.
As a suction feeder, A. fenestralis utilizes a specialized feeding mechanism it rapidly expands its buccal cavity to create negative pressure, effectively pulling prey into its mouth. Its primary prey items include gammarid amphipods, isopods, shrimp, and bivalves, with smaller proportions of gastropods, polychaetes, and other benthic organisms also contributing to its diet. The species is particularly adapted to feeding on benthic organisms in rocky habitats, where its suction-feeding strategy allows it to efficiently capture sedentary prey.
Artedius fenestralis primarily reproduces through external fertilization, where eggs are laid and fertilized outside the female's body.[7] However, there is evidence suggesting some degree of reproductive flexibility. In laboratory conditions, eggs of A. fenestralis were observed to develop even in the absence of added sperm, indicating the possibility of internal gamete association (IGA), where sperm may already be present in the female before the eggs are laid.
Male A. fenestralis exhibit parental care, which is a critical aspect of the species' reproductive strategy. After fertilization, males guard the eggs until they hatch, protecting them from predators and other threats. This guarding behavior is common in cottid fishes and significantly enhances the survival rate of the offspring. Interestingly, males often guard multiple clutches of eggs at once, which may increase their reproductive success by attracting additional females who are more likely to mate with a male that already has eggs.
Female mate choice is influenced by many factors. In laboratory experiments, females showed a preference for males already guarding eggs, suggesting that egg-guarding males are perceived as more desirable mates. Larger males also tended to attract more clutches, indicating that size plays an important role in mate selection. This reproductive behavior highlights the importance of both size and parental care in ensuring reproductive success in A. fenestralis.
In terms of breeding season and location, A. fenestralis spawns in shallow waters, typically within rocky intertidal zones or near kelp forests, where the structural complexity of the habitat offers protection for the developing eggs. The species' strong site fidelity and preference for specific breeding grounds are consistent with behaviors observed in other sculpins, where localized breeding populations often form.
Growth of Artedius fenestralis tends to be slow. Because the species’ benthic lifestyle in rocky and kelp-dominated environments often offers less opportunity for fast growth compared to more open-water species. These rocky environments usually provide limited access to high-energy prey items. The species' diet may also lack the caloric density to support rapid growth rates. The cooler and more stable temperatures in habitats further contribute to a slower metabolism, impacting growth rates.
Artedius fenestralis has been reported to host several species of nematodes, particularly those belonging to the family Cystidicolidae, which are common parasites in marine fishes.[8] Among the nematodes found in A. fenestralis, Trichodina vancouverense, and T. decipiens are of particular interest, as they are unique to this species and were first described in association with it.[9] These nematodes parasitize various tissues, where they can influence the fish's health and energy availability, particularly during stressful periods.
Nematode infections in A. fenestralis are part of a broader ecological relationship between marine fishes and their parasites, with environmental factors such as habitat and water quality playing key roles in the prevalence and intensity of these infections. This parasitic relationship may also indicate the sculpin's role in marine food webs, as nematodes often use intermediate hosts such as invertebrates, which are common prey for A. fenestralis.