Feather Stars (Crinoids) in Mauritius

Feather stars, belonging to the genus Comanthina and the broader class Crinoidea, are among the oldest and most captivating invertebrates found in Mauritius's warm Indian Ocean waters. Related to sea urchins, starfish, and sea cucumbers, these echinoderms are living relics of a prehistoric marine world, and their presence on Mauritian reefs is a testament to the island's exceptional biodiversity.

Appearance and Identification

Feather stars are unmistakable once you know what to look for. Their bodies consist of a central disc called the calyx, from which radiate multiple arms – typically between 10 and 20 – that are lined with feathery pinnules. These pinnules give the animal its characteristic plume-like appearance. In Mauritius, Comanthina species display a stunning range of colours, including deep burgundy, vivid yellow, electric green, and striking black-and-white combinations. Unlike their stalked relatives the sea lilies, feather stars are free-living and can relocate by walking on flexible cirri – claw-like appendages that anchor them to the substrate.

Behaviour and Feeding

Feather stars are suspension feeders, extending their arms into passing currents to capture tiny planktonic organisms and organic particles. Small tube feet lining the pinnules are coated in mucus that traps food, which is then conveyed along a groove to the central mouth. You'll often observe feather stars positioned on elevated perches – the tips of sea fans, sponge outcrops, or coral heads – to maximise their exposure to food-rich water flow. They are most active at night, when plankton rises through the water column, though they are commonly visible during the day on Mauritius's reefs. When disturbed, feather stars can actually swim by rhythmically beating their arms, a surprisingly agile escape response for such a delicate-looking creature.

Habitat in Mauritius

In Mauritius, feather stars thrive across a variety of reef environments, from the shallow lagoons inside the fringing reef to deeper outer reef slopes and drop-offs. They are particularly common in areas with moderate to strong currents, where plankton is abundant. Sites along the west coast and around the northern tip of the island host healthy populations. They are frequently found clinging to sea fans (Gorgonia spp.), barrel sponges, and hard coral formations at depths ranging from 5 to 30 metres, making them accessible to both snorkellers and scuba divers.

Ecological Role

As filter feeders, feather stars play an important role in nutrient cycling on coral reefs. They also serve as microhabitats for a range of small commensal species. Look carefully at a feather star in Mauritius and you may discover tiny shrimp and brittle stars living cryptically among its arms, perfectly camouflaged to match their host's colouration. This commensalism is a wonderful example of reef interdependency.

Diving with Feather Stars in Mauritius

Feather stars are a common sight on guided dives around Mauritius, and experienced dive operators on the island will point them out as part of a broader introduction to reef invertebrate life. For the best experience, divers should move slowly and avoid disturbing the substrate, which can cause feather stars to retract their arms defensively. Underwater photographers will find feather stars extraordinarily rewarding subjects – their symmetrical forms and vivid colours create striking macro and wide-angle compositions. Night dives offer a particular treat, as feather stars fully extend their arms and their feeding behaviour is at its most active.

Conservation

Feather stars in Mauritius are not currently under direct threat from targeted harvesting, but like all reef invertebrates, they are vulnerable to coral reef degradation caused by climate change, ocean acidification, and poor water quality. Supporting responsible dive operators, avoiding contact with reef life, and choosing reef-safe sunscreen all contribute to preserving the habitats these ancient animals depend upon.