Echiurida (order)

Scope note: Formerly considered a separate phylum; now generally classified as an order of annelids. Contains primarily marine invertebrate sausage-shaped organisms, that have lost their segmentation, found in sand and mud of tropical and subtropical seas. A flattened extension of the head is curved along its lateral edges and sometimes shaped like a scoop or spoon to form a nonretractable anterior proboscis. Some respiration probably takes place across the body wall, but the hind gut is often utilized as a respiratory organ by drawing water through the anus.

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