Let me share with you a difference between hemichordates and chordates.
| Aspect | Hemichordates | Chordates |
| Presence of notochord | Absent or rudimentary structure called a stomochord | Notochord present, typically as a flexible rod-like structure supporting the body. |
| Nervous system | Simple, with a nerve net | More complex, with a dorsal hollow nerve cord |
| Gill slits | Present, used for filter-feeding in some species | Present, often used for filter-feeding or respiration |
| Post-anal tail | Absent | Present in at least some stage of the life cycle |
| Segmentation | Generally absent in adults | Present in some groups e.g., vertebrates |
| Circulatory system | Simple, often with a tubular heart | More complex, with a chambered heart in many species |
| Pharyngeal slits | Present but not considered true gill slits | Present, and may function in feeding or respiration |
| Notocord development | In some species, the stomochord may persist throughout life | Develops into the vertebral column in vertebrates |
| Body shape | Worm-like in appearance | Complex body plans, including fish, mammals and humans |
| Dorsal hollow nerve cord | Generally absent | Present, runs along the dorsal side of the body |
| Examples
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· Acorn worms (Enteropneusta)
· Pterobranchs
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· Fishes
· Amphibians · Reptiles · Birds · Mammals
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