Aphelasterias japonica

Aphelasterias japonica is a medium sized sea star that has five elongated arms extending from a small central disc. Individuals can reach approximately 20-30 cm in diameter. The aboral (upper) surface is reddish to pink, while the oral surface is lighter in color. The body surface contains small spines and pedicellariae, which are structures found in sea stars and are used for protection and cleaning the body surface. It uses tube feet (podia), located along ambulacral grooves, for movement and feeding.

Aphelasterias japonica is native to the northwestern Pacific Ocean and has been recorded along the coastal waters of Japan and the Russian Far East. It occurs across a broad range, from intertidal and subtidal zones to depths of up to 300m, but is most found around 5-20 meters within water temperatures of 10-25 °C. The species inhabits a wide range of habitats, including rocky, sandy and muddy substrates, as well as gravel beds. It is also found in more complex habitats like kelp forests, coralline algae beds, and shellfish reefs.

Aphelasterias japonica is a mobile benthic predator that feeds mainly on mollusks and other echinoderms such as clams, sea cucumbers, and sea urchins. Like other sea stars, it captures prey using its tube feet and digests food externally by everting its cardiac stomach. This allows it to break down and consume organisms with hard shells that would otherwise be difficult to eat. The ability of A. japonica to move through different substrates allows it to take advantage of patchy food resources and find a variety of prey species. It contributes to trophic interactions between predator and prey populations within its coastal marine ecosystems. In addition to direct predation, A. japonica produces bioactive chemical compounds known as asterosaponins, which function as part of its chemical defense system. These compounds have been shown to cause toxic effects on marine organisms under experimental conditions, including embryotoxic and cardiotoxic effects in fish models. These results suggest that the ecological impact of A. japonica is not only based on its feeding behavior. Its chemical defenses may also influence how it interacts with other organisms and its surrounding environment. …