What do fleas look like and how do they jump? - briefly
Fleas are minute, laterally compressed insects measuring roughly 1–3 mm, possessing a hard exoskeleton, prominent hind legs, and spiny rows for gripping fur. They propel themselves by releasing elastic energy stored in a resilin pad at the leg joint, generating accelerations of up to 100 g and allowing jumps many times their body length.
What do fleas look like and how do they jump? - in detail
Fleas are tiny, laterally compressed insects measuring 1–4 mm in length. Their bodies are covered with fine, backward‑pointing setae that reduce friction and aid movement through host fur. The exoskeleton is hardened, dark brown to reddish, and segmented into head, thorax, and abdomen. The head bears large, compound eyes and short antennae composed of 6–9 segments. Mouthparts form a piercing‑sucking proboscis, enabling blood extraction from mammals and birds. The thorax supports six powerful legs; each leg ends in a claw that grips hair shafts.
Jumping relies on a specialized elastic mechanism. The process involves:
- Energy storage: The flea contracts a resilin‑rich protein pad (the "pleural arch") in the femur, building tension.
- Trigger release: A latch mechanism, formed by the tibial spur and a cuticular lock, suddenly disengages.
- Power amplification: Stored elastic energy converts to kinetic energy, propelling the flea up to 150 times its body length (≈30 cm) and achieving accelerations of 100 g.
- Control: The hind legs, equipped with a spring‑like structure called the "tarsal pulley," direct the thrust, while the forelegs stabilize the landing.
The combination of a compact, aerodynamic shape and the resilin‑based spring system enables fleas to escape predators and move between hosts with remarkable speed.