Hemichordata General Characteristics, Classification and Examples | Free Biology Notes

Hemichordata General Characteristics, Classification and Examples

After reading this article you will learn about Hemichordata General Characteristics, Classification and Examples

Hemichordata General Characteristics

• The body is cylindrical, unsegmented and divided into three parts:- Proboscis, Collar and Trunk.
• Stomochord is a hollow outgrowth arise from the roof of buccal cavity and it is present in proboscis
• Respiration takes place through gill
• Circulatory system is open type and blood is colourless
• Respiratory pigment vanadium is present
• Excretion occurs through proboscis gland
• Reproduction is sexual and they unisexual
• Fertilization is external and development is indirect with tornaria larva
• Hemichordata is connecting link between non-chordates and chordates

Classification of Hemichordata

Class 1. Enteropneusta

• They are solitary animals
• Trunk long
• Alimentary canal straight
• Mouth and anus at opposite ends
• E.g. Balanoglossus, Saccoglossus

Class 2. Pterobranchia

• Sedentary and colonial marine animals
• Trunk short, sac-like
• Alimentary canal U-shaped
• Anus situated near the mouth at the same end
• E.g. Rhabdopleura, Cephalodiscus

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