madreporite

The madreporite is an opening used to filter water into the water vascular system of echinoderms. It is visible as a small red or yellow button-like structure, looking like a small wart, on the aboral surface of the central disk of a sea star. Close up, it is visibly structured, resembling a 'madrepore' colony. From this, it derives its name. The water vascular system of the sea star consists of a series of seawater-filled ducts that function in locomotion and feeding and respiration. Its main parts are the madreporite, the stone canal, the ring canal, the radial canals, the lateral canals, and the tube feet. The sieve-like madreporite allows entry of seawater into the stone canal, which connects to the ring canal around the mouth. Five or more radial canals extend from the ring canal, one in each arm above the ambulacral groove. From the radial canals extend many lateral canals, each of which leads to a tube foot. Each tube foot is a closed cylinder with muscular walls, having a sucker at the outer end and a bulb-like ampulla at its inner end within the body cavity.

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What is a madreporite?
The madreporite is a specialized porous plate or button-like structure found on the aboral (upper) surface of echinoderms such as sea stars, sea urchins, and brittle stars. It serves as the water intake opening for the water vascular system.
What is the function of the madreporite?
The madreporite filters seawater entering the water vascular system of echinoderms. It acts as a strainer, allowing water to flow into the stone canal and subsequently into the radial canals and tube feet, which are used for locomotion, feeding, and gas exchange.
Where is the madreporite located on a sea star?
In sea stars (asteroids), the madreporite is visible as a small, light-colored, porous plate on the aboral (upper, dorsal) surface of the central disc, typically between two of the rays (arms). It leads to the stone canal internally.
What connects the madreporite to the rest of the water vascular system?
The madreporite connects to the stone canal, a calcified tube that leads to the ring canal surrounding the esophagus. From the ring canal, radial canals extend into each arm, branching into lateral canals and finally tube feet (podia).
Do all echinoderms have a madreporite?
Most echinoderms have a madreporite, including sea stars, brittle stars, sea urchins, and sand dollars. Sea cucumbers (holothurians) are exceptional in that they typically have a madreporite that is internal rather than external.

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mucus body coating mucous body coating mucus cocoon mucous cocoon Mullerian duct ductus paramesonephricus multi cell part structure cell part cluster multicellular anatomical structure multicellular structure multilaminar epithelium laminated epithelium multi-tissue structure multi-tissue structures multi-unit eye

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This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical decisions.

Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.