Hierarchy classification:

1. top of the aat hierarchies
2. Agents Facet
3. Living Organisms (hierarchy name)
4. living organisms (entities)
5. Eukaryota (domain)
6. Animalia (kingdom)
7. Annelida (phylum)
8. Echiura (class)

Anotations

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.