Question

Cleavages in protostomes are

• A. Radial
• B. Spiral
• C. Circular
• D. Lateral

Answer 1

The correct option is B Spiral

• Protostomes are bilaterally symmetrical triploblastic animals.
  
• They are so called because in them the mouth is formed first and then the anus.
• When the cleavage planes are not parallel or perpendicular to the animal-vegetal pole axis of the ova or egg it is called spiral cleavage.
• In Protostomes, the cleavage takes place at oblique angles which form a spiral pattern of daughter blastomeres.
  
• This type of cleavage pattern is characteristic of Protostomes.
• So, the correct answer is 'Spiral'.