Dark bands alternate with pale bands along each arm. The banded brittle star is one of the most beautiful of New Zealand's brittle stars. Its arms are striped like a tiny serpent. The pattern provides camouflage against the rocky seafloor. It breaks up the outline of the arm when it moves. Visibility is low. Survival is high. Under rocks and in crevices it hides during the day. The banded brittle star is nocturnal. It emerges only after dark to feed. It wedges itself into gaps where predators cannot reach. During the day it is still and silent. Its arms are tucked close to its body. At night it unfolds. It stretches its banded arms into the water. Stillness is safety. Motion is risk. The arms are long and slender. They are capable of spanning fifteen centimetres. They are flexible. They coil around rocks and kelp stalks. When the brittle star moves the arms writhe like snakes. The disc is small. Only one to two centimetres across. But the arms keep going. They search for food. Proportion is skewed. Reach is extensive. When threatened the arms break. This is a defence mechanism. A brittle star that is grabbed by a predator will shed the captured arm. It leaves the arm writhing in the attacker's grasp. The rest of the animal escapes. The arm regenerates within weeks. It is a costly defence. But it works. Sacrifice ensures survival. Loss is temporary. Regrowth is certain. Rocky reefs and kelp forests provide its preferred habitat. The banded brittle star lives from the low tide mark down to fifty metres depth. It occurs on reefs in harbours and in estuaries. It is most common in areas with complex rocky structure. These are the kinds of places with plenty of crevices to hide in. It is a common sight for night divers. Complexity offers shelter. Simplicity offers exposure. The Māori name Pēwhā refers to its sinuous snake-like movement. The arms twist and coil. They move with a grace that seems impossible for an animal with no obvious muscles. It is a fitting name for a creature that seems to flow rather than crawl. Language captures motion. Name reflects form. Climate change may affect it indirectly. Warming waters and ocean acidification may impact the planktonic larvae that drift before settling. The banded brittle star is resilient. But it has limits. For now it remains common on rocky reefs. It hides under rocks during the day. It unfurls its banded arms at night. Resilience is tested. Limits are unknown.