Proboscis gland is a/an

Hemichordates are:

Which of the following animals are exclusively marine and generally tube-dwelling?

During a field trip,a student observed a marine organism with a worm-like body. The cylindrical body was divided into a proboscis,collar,and a long trunk. The organism may be . . . . . .

Which group of animals possesses a $U$-shaped digestive tract?

Balanoglossus is now classified under which of the following?