🌑Defination
🔴Hemichordates are marine invertebrate worm like animals.
🔴This is phylum which has close relationship with chordates and Echinodermata.
🔴Earlier, Hemichordata were considered as chordates but now put in a separate phylum under non chordata.
🌑General characters
🔴Hemichordates have a rudimentary structure in collar region called stomochord which is similar to notochord. 🔴Animals are worm like, marine with organ system level organisation.
🔴Their Animals are cylindrical and body is divided into proboscis, Collar and trunk. 🔴Circulatory system is open type.
🔴Respiration takes place by gills.
🔴Saxes are separated. Fertilisation are external. Development is indirect.
🌑Examples of Hemichordata
🟡 Balanoglossus
🔴It is also known as Acorn worm.
🔴It is deuterostome because anus is developed before mouth.
🔴It is worm like animals marine animals.
🔴Body is divided into proboscis, Collar and trunk.
🔴The alimentary canal is straight starting from mouth and ending with anus.
🔴It has U shaped paired gills slit.
🔴Notochord is present on upper part of body without nerve chord.
🔴Saxes are separated. Fertilisation are external. Development is indirect.
🟡 Saccoglossus
🔴It is soft body animals and body is divided into Proboscis collar trunk.
🔴It is found in spirally coiled burrow in ocean.
🔴It uses its proboscis to push the body on sand.
🔴Mouth is located internally at junction of Proboscis and collar.
🔴The gills are located internally in trunk region.
🔴It has Glomerulus in proboscis which filter and release the excretory waste.
🔴The egg are converted into tornaria larva which undergo metamorphosis into young animals.
1. Which of the following phylum were earlier considered as chordates but now is a non chordates under separate phylum.
A. Echinodermata
B. Hemichordata
C. Mollusca
D. Urochordata
Answer: B
2. Which of the following structure is present in Hemichordates as rudimentary.
A. Spinal cord
B. Nerve cord
C. Notochord
D. Stomochord Answer: D
3. Stomochord is present in Hemichordates in
A. Proboscis region
B. Collar region
C.Trunk region
D. Glomerulus
Answer: B
4.Which one of the following statement is not correct with respect to Hemichordates.
A. They are worm like and present in both fresh and marine water.
B. They are Triploblastic and have bilateral symmetry.
C. They are true Coelomate with organ system of body organisation.
D. They have stomochord which seem like notochord.
Answer: A
5.Body of Hemichordates is divided into
A. Proboscis collar and trunk
B. Head and trunk
C. Thorax and abdomen
D. Head, foot and visceral hump
Answer: A
6. Hemichordates respires by
A. Trachea B. Gills
C. Spiracle D.lungs
Answer: B
7. Proboscis glands in Hemichordates is involved in
A. Respiration
B. Excretion
C.Transportation
D. Locomotion
Answer: B
8. Consider the following features of Hemichordata and select the correct code
1. Open circulatory system
2. External fertilisation
3. Separated sex
4. Indirect development
A. 1 2 and 3
B. 2 3 and 4
C. 1 3 and 4
D. 1 2 3 and 4
Answer: D
9. Which of the following animals belong to Hemichordata.
A. Ctenoplana & Pleurobranchia
B. Balanoglossus & Pleurobra chia
C. Saccoglossus & Pleurobranchia
D. Balanoglossus and Saccoglossus
Answer: D
10. Identify the number 1 and 2 in given Diagram
A. Proboscis and Collar
B. Collar and trunk
C. Proboscis and trunk
D. Collar and trunk
Answer: A
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