Specimen Showcase｜A Brittle Yet Resilient Star Beneath the Waves
- Hong Kong Biodiversity Museum
- Apr 8
- 3 min read
The Common Brittle Star, 𝘖𝘱𝘩𝘪𝘰𝘵𝘩𝘳𝘪𝘹 𝘧𝘳𝘢𝘨𝘪𝘭𝘪𝘴 (Abildgaard, 1789) is a captivating echinoderm that brings a splash of intrigue to the waters off the British Isles and throughout the North Sea, extending all the way down to the Cape of Good Hope in South Africa. These creatures thrive in a variety of habitats💪🏻, from shallow coastal zones to depths of up to 350 meters. Known for their social behavior, they often gather in massive groups called brittle star beds, with populations that can reach a staggering 2,000 individuals. While you might spot them living solo in the intertidal zone, they truly shine in areas with hard substrates and strong currents, skillfully avoiding high sedimentation zones that could interfere with their feeding and respiration.
Easily recognized by their distinctive appearance, common brittle stars feature a central disc measuring 2 to 20 mm in diameter, surrounded by five long, slender arms that can be five times the disc's diameter. Adorned in shades of red, white, or brown🌈, sometimes with charming bands or spots, they excel at blending into their surroundings. Unlike their starfish relatives, these agile stars scurry about using a rowing motion, thanks to their segmented arms covered in tiny spines and equipped with tube feet for movement and feeding🍽️.
As nighttime foragers, common brittle stars showcase their cryptic behavior by tucking away under rocks and in crevices during the day🙈. As opportunistic feeders, these clever echinoderms primarily delight in a buffet of decaying organic matter from the ocean floor. They employ a passive suspension feeding strategy, gracefully extending their slender arms through crevices to gather food particles, which they then transport to their mouths using specialized tube feet. Their diet mainly consists of detritus, diatoms, and phytoplankton, with occasional scavenging for tasty dead material. Plus, their ability to secrete sticky mucus from their tube feet makes collecting food a breeze, turning them into true culinary masters of the underwater world🧑🏻🍳.
The common brittle star embarks on an intriguing journey through three major life stages: larva, juvenile, and adult. Reaching sexual maturity at around 10 mm in body disc diameter, these stars kick off their reproductive adventure from May to July. During spawning, males release sperm into the water, prompting females to follow suit by releasing eggs, leading to a spectacular underwater fertilization event. The larvae drift in the water column for about 20 to 30 days, soaking up their surroundings before settling down and metamorphosing into juveniles. Initially reliant on adult brittle stars for food, these young stars gradually learn to fend for themselves, making their way in the vibrant marine world🗺️.
To stay one step ahead of predators like fish, crabs, and starfish, common brittle stars have developed some clever defense strategies. With their cryptic coloration, they blend seamlessly into their surroundings, often hiding during the day and emerging to feast at night🌃. But that's not all—they possess a remarkable trick up their sleeves (or rather, arms)! When threatened, these crafty stars can shed an arm in a process known as autotomy. This not only distracts their would-be attackers, giving them a chance to escape, but they can also regenerate the lost limb over time. It’s a fantastic survival strategy that showcases their resilience and adaptability in the underwater world🦾.
In the wild, common brittle stars typically enjoy a lifespan of around 10 years. These adaptable stars thrive in diverse environments, from rocky reefs to sandy bottoms, and their tendency to gather in large offshore groups boosts their chances of survival in the dynamic marine ecosystem. Not only are they fascinating creatures with intriguing behaviors, but they also play a crucial role in recycling nutrients♻️and maintaining the health of benthic environments. With their unique adaptations and lively social habits, these stars offer a captivating glimpse into the complexity of marine life, proving that even the smallest stars can shine brightly in the underwater world✨.
Does the brittle star raise your interest in ecology and biodiversity🔎? If your answer is positive, come to the Hong Kong Biodiversity Museum where we have a wide variety of specimens, from sponges to bats, and you can learn more about their fascinating ecology. If you found this article📝engaging, share it with your friends and stay tuned for our captivating biodiversity narratives released weekly!
Text: Millicent
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