Echiurida
Nota de aplicación
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 …