The chocolate chip starfish (Protoreaster nodosus) is a marine invertebrate recognized for its distinctive appearance. Its body is adorned with dark, raised nodules resembling chocolate chips, making it a popular aquarium inhabitant. Understanding its dietary needs is important for maintaining its health and the balance of its marine environments.
Natural Diet
In their natural marine habitats, chocolate chip starfish are opportunistic scavengers. Their diet primarily consists of detritus, decaying organic matter found on the seafloor. They also consume algae, including microalgal films and biofilms.
These starfish actively prey on small benthic invertebrates like worms. They are known to consume sessile organisms such as sponges, soft corals, tubeworms, and bivalves like clams and mussels. Occasionally, they feed on carrion.
Feeding Mechanisms
Chocolate chip starfish employ a unique and fascinating feeding mechanism involving the eversion of their stomach. When encountering food, the starfish extends its cardiac stomach out through its mouth, which is located on its underside. This allows the stomach to envelop the food item externally.
Once the stomach is everted and covers the prey, the starfish releases digestive enzymes directly onto the food. These enzymes break down the food externally, turning it into a liquid or semi-liquid form. The liquefied nutrients are then absorbed by the stomach before it is retracted back into the body.
The starfish uses its numerous tube feet, located on the underside of its arms, to manipulate food and to hold onto surfaces while feeding. These tube feet are especially useful for prying open the shells of bivalves, allowing the starfish to access the soft tissues inside. This external digestion process enables them to consume prey larger than their mouth opening.
Diet in Captivity
Providing an appropriate diet for chocolate chip starfish in a home aquarium is important for their well-being. Suitable food sources include a variety of meaty items such as frozen mysis shrimp, brine shrimp, chopped pieces of fish, squid, and bivalves like clams or mussels. Sinking pellets and specialized invertebrate foods are also acceptable.
A varied diet is important to ensure comprehensive nutritional intake for the starfish. Feeding can be done a few times a week, or when the starfish appears to be actively searching for food. To ensure the starfish receives its share, especially in community tanks, spot-feeding by placing food directly on or near the starfish is often effective.
It is important to note that chocolate chip starfish are not considered reef-safe and can pose a risk to other aquarium inhabitants. They have a tendency to consume corals, sponges, tubeworms, snails, and other invertebrates if not adequately fed or if food sources are scarce. For this reason, they are generally recommended for fish-only-with-live-rock (FOWLR) aquarium setups.