How do fleas jump onto cats? - briefly
Fleas store elastic energy in a resilin pad within their hind legs and release it in a millisecond burst, propelling them up to 100 times their body length toward a host. They detect a cat by sensing body heat, carbon‑dioxide and movement, then launch at an optimal angle to reach the animal’s fur.
How do fleas jump onto cats? - in detail
Fleas achieve vertical displacement through a specialized elastic structure located in their hind legs. The protein resilin forms a highly stretchable pad that stores mechanical energy when compressed. Muscular contraction compresses this pad, and the sudden release converts stored energy into kinetic force, propelling the insect upward at speeds exceeding 1 m s⁻¹ and reaching heights of 15–30 cm—far beyond its body length.
The launch sequence follows a precise order:
- Sensory detection – thermoreceptors, CO₂ receptors, and mechanosensors identify a warm, carbon‑rich host nearby.
- Pre‑launch positioning – the flea aligns its body, flexes the hind femur, and engages the resilin pad.
- Energy accumulation – leg muscles contract, compressing the pad and loading elastic potential.
- Rapid release – the pad expands, generating an impulsive thrust that accelerates the flea into the air.
- Mid‑air adjustment – aerodynamic surfaces on the thorax and abdomen stabilize trajectory.
- Contact and adhesion – specialized claws and a set of microscopic setae grip the cat’s fur upon impact, preventing slip.
Temperature gradients on a cat’s skin provide the thermal cue that triggers the sensory cascade, while the animal’s exhaled CO₂ creates a chemical gradient that guides the flea toward the host. Vibrations transmitted through the fur further refine the approach, allowing the parasite to time its jump when the cat is stationary or moving slowly, conditions that maximize successful attachment.
After landing, the flea’s claws interlock with individual hair shafts, and the setae generate van der Waals forces that hold the insect in place while it begins feeding. This combination of rapid elastic energy release, multimodal sensory guidance, and mechanical adhesion enables fleas to consistently reach and remain on feline hosts.