Meaning and Origin of Foot: Phylum Mollusca is characterised by the pronounced development of musculature known as the foot. It is the locomotory organ in Molluscs. This organ is quite uncommon and strange to others. It is regarded as the remnant of the 'dermo-muscular tube' of the ancestral form whose ventral side became greatly developed as an adaptation for creeping [...]
In this article we will discuss about Sepia:- 1. Habit and Habitat of Sepia 2. External Structures of Sepia 3. Coelom 4. Digestive System 5. Locomotion 6. Respiratory System 7. Circulatory System 8. Excretory System 9. Nervous System 10. Reproductive System 11. Development. Habit and Habitat of Sepia: Sepia is a typical representative of the class Cephalopoda. Members of this [...]
Definition: Torsion (twisting) is the rotation of visceral organs in anticlockwise direction through an angle of 180° on the rest of the body during larval development. The phenomenon takes place in the free-swimming (veliger) larva of gastropods and converts the symmetrical larva into an asymmetrical adult. Contraction of the larval retractor muscles and differential growth are possibly responsible for such [...]