Phylum- Hemichordata [Acorn worms]:
- Body of these animals is divided into three parts as -proboscis, collar and trunk.
- Notochord is present in proboscis region only.
- Marine animals, live in burrows in sand.
- Have one to many pharyngeal gill slits.
- Unisexual or some may be hermaphrodite.
- Ex.: Balanoglossus, Saccoglossus.
- Balanoglossus is considered as connecting link between non-chordates and chordates.