Squid Worm

Teuthidodrilus shares presence of body papillae, a subterminal mouth, presence of grooved prostomial palps, branchiae restricted to the anterior region of the body, and a single pair of large anteriorly located nephridia with Flabelligeridae and Acrocirridae. Teuthidodrilus exhibits the gelatinous sheath, position of the nephridiopores and branchial membrane of a flabelligerid, but possesses the spinous chaetae and nonretractable head of an acrocirrid. The size, shape and length of branchiae, few body papillae, and shape of the notochaetae (broad, flattened, concavo-convex, with abrupt tapering to a fine tip distally) and neurochaetae (simple instead of pseudocompound as is typical of benthic acrocirrids) distinguish Teuthidodrilus from all other acrocirrids.