White Starfish

Echinoderm

Identification & Biology

• IdentificationA medium-sized starfish that is unusual in often having six or seven arms instead of the typical five. Colour ranges from grey-green to brown, sometimes with lighter patches. The arms are robust and covered in small spines. Can regenerate arms and even split in half.
• SizeArm span up to 25 cm.
• Social HabitSolitary. Capable of asexual reproduction by dividing itself across the central disc, with each half regenerating the missing arms. This means many individuals have arms of different lengths, indicating recent regeneration.
• HabitatRocky reefs, boulder fields, and rubble areas. Prefers shallow, sheltered environments.
• Depth0 to 40 m. Most common between 2 and 20 m.
• Feeds OnMussels, barnacles, gastropods, and other small invertebrates. Prises open bivalves and digests prey externally.
• DistributionEastern Atlantic from the British Isles to West Africa, and throughout the Mediterranean Sea. Common in Maltese waters.
• DescriptionCoscinasterias tenuispina is one of the most interesting starfish in Malta because of its habit of reproducing by tearing itself in half. The two halves each regenerate the missing arms, resulting in individuals with oddly asymmetric arm arrangements. If you see a starfish with some arms noticeably shorter than others, it has likely split recently. This asexual reproduction makes it one of the faster-colonising starfish species.