Sea Urchins / Lå'on
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Sea Urchins / Lå'on
Echinothrix diadema
Sea urchins, called lå'on in Chamoru, belong to a group of animals known as echinoderms which also includes starfishes and sea cucumbers. The word echinoderm means "spiny skin" and refers to the bony plates, spines, or spicules which either cover or are imbedded in the skin.
Echinoderms also have a body plan based on radial symmetry in which many of the body parts are arranged symmetrically like spokes radiating from a common center. Echinoderms do not have a brain, eyes, or ears, but have a nerve network that enables them to function.
Lå'on have an outer shell called a test which consists of interlocking plates. Each plate has rows of sockets that hold either spines or pinching appendages called pedicellariae. A thin outer skin covers the test. A mouth with teeth is located in the center of the underside of the test.
Flowery urchin / Toxopneustes pileolus
Images from Coral Reefs CD
Lå'on feed by rasping algae from the bottom. Waste products are passed through a small hole on the top of the test. Digestive and reproductive organs are located inside the test. The cream-colored eggs of many lå'on are a delicacy and lå'on are harvested for food in many places.
There at least 28 kinds of lå'on on Guam. Most have sharp brittle spines that can break off on contact and cause painful wounds. The spines of some kinds are slightly venomous. Most lå'on wounds are not serious; usually the pain subsides in a few hours and particles of spine dissolve in a day or two. Soaking the wound in hot water may speed the healing process.
Many lå'on have venomous flower-like pedicellariae. The flowery urchin is covered with colorful pink pedicellariae which can cause extremely painful wounds that may last several days. This urchin is not always noticed because it covers itself with bits of debris. All sea urchins have soft tubed feet with suction cups at the end. These are used to cling to the bottom, transport food particles, and hold debris for camouflage.
Guam Comprehensive Wildlife Conservation Strategy, 9/27/2005
