Motility of spirochaetes — Which statement best describes the motility exhibited by spirochaetes under the microscope?

Introduction / Context:
Spirochaetes (e.g., Treponema, Borrelia, Leptospira) are thin, helical bacteria that move using endoflagella (axial filaments) located within the periplasmic space. Their unique structure results in distinctive motility patterns that aid in microscopic recognition.

Given Data / Assumptions:

• Observation is typically made using dark-field or phase-contrast microscopy.
• Endoflagella anchor at each end and overlap around the protoplasmic cylinder.
• Movement reflects rotation of the axial filament complex relative to the cell body.

Concept / Approach:
The endoflagella-driven mechanism generates multiple observable motions: a corkscrew-like (rotatory) movement that helps penetrate viscous media; flexion and extension (bending) of the helical body; and translatory (forward) motion as the cell progresses. Because spirochaetes exhibit all three, the comprehensive answer is “all of the above.”

Step-by-Step Solution:

Verification / Alternative check:
Dark-field videos of Treponema pallidum show all three components of movement, validating this description.

Why Other Options Are Wrong:

• Choosing a single mode ignores the composite nature of spirochaete motility driven by axial filaments.

Common Pitfalls:
Confusing spirochaete motility with flagellated rods; classical external flagella produce different swimming patterns.

Final Answer:
all of the above