Multicellular , small group, bilaterally symmetric. Segmentation visible in some structures. Real coelom lined with mesoderm is sometimes lost. Direct, or indirect with a tornaria larvae which resembles the bipinnaria larvae in echinoderms.
Sensory organs are visual, touch, and chemoreceptive senses concentrated on the head.
Gas exchange is through integument, and oxygen is carried in blood and pumped with a contractile heart vesicle into sinuses in the open circulatory system. Complete with mouth and anus. Glomerulus is specialization of the circulatory system Reproduction asexual reproduction by fragmentation or budding. Compare and contrast Hemichordates with Echinoderms and Chordates.