Phylum Hemichordata - Characteristics Features -
- These are marine worm-like animals.
- They bear a resemblance to the chordates in having pharyngeal gill slits.
- They also bear a resemblance to the phylum Echinodermata.
- They show the following characteristic features:
- They have an unsegmented body with organ level of body organization
- They are triploblastic, coelomate and bilaterally symmetrical
- The body is divided into three parts as: proboscis, collar and trunk
- The proboscis has a buccal diverticulum or stomochord. It was earlier considered as notochord.
- They have an open type of circulatory system
- Gills are used for respiration
- Proboscis gland is the excretory organ
- They are dioecious. Fertilization occurs externally and development is indirect
- Examples: Balanoglossus, Saccoglossus

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Tornaria larva of hemichordates is planktonic and similar to the bipinnaria larva of echinoderms. They have a convoluted band of cilia.
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