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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