How do fleas hop? - briefly
Fleas achieve their extraordinary jumps by compressing a resilient protein pad called resilin in their hind‑leg tibiae, then releasing the stored elastic energy almost instantaneously. This catapult‑like action propels them upward 100 times their body length with minimal muscular effort.
How do fleas hop? - in detail
Fleas achieve extraordinary leaps through a specialized catapult system located in their enlarged hind legs. The legs contain a protein called resilin, which functions as an elastic spring. Muscles contract slowly to deform the resilin pad, storing potential energy without producing immediate movement. When the flea decides to jump, a latch mechanism releases the stored energy, converting it into kinetic energy in a fraction of a millisecond.
The hind femur is elongated and equipped with a robust tibial spur that acts as a lever. Upon release, the resilin pad expands, thrusting the tibia forward and propelling the body upward. This rapid extension generates accelerations exceeding 100 g, allowing a flea to cover distances up to 150 times its body length (approximately 20 cm) and reach heights of 15 cm.
Neural control coordinates the timing of muscle contraction and latch release. Sensory receptors detect substrate vibrations; when a suitable host is sensed, a burst of motor neuron activity initiates the loading phase. The latch, formed by a cuticular structure, remains closed until a precise neural signal triggers its opening, ensuring consistent jump performance.
Key quantitative characteristics:
- Maximum launch speed: ~1 m s⁻¹
- Acceleration: >100 g
- Jump distance: up to 0.2 m (≈150 body lengths)
- Jump height: up to 0.15 m
The combination of elastic energy storage, a mechanical latch, and rapid leg extension enables fleas to overcome their small mass and achieve jumps that rival much larger organisms. This mechanism is a hallmark of arthropod locomotion adaptation, illustrating how microscopic structures can produce macroscopic performance.