How do fleas attack? - briefly
Fleas detect hosts through heat, carbon‑dioxide emissions, and motion, then leap onto the skin, pierce the epidermis with specialized mouthparts, and ingest blood. Their saliva injects anticoagulants that keep the wound open for uninterrupted feeding.
How do fleas attack? - in detail
Fleas are obligate ectoparasites that locate, reach, and feed on a host through a rapid, mechanically precise sequence.
The search for a suitable animal relies on three sensory cues: body heat, carbon‑dioxide exhalation, and tactile vibrations. Antennae equipped with thermoreceptors and chemoreceptors detect temperature gradients and CO₂ plumes, while mechanoreceptors perceive movement through the substrate. These signals guide the insect toward a potential victim.
When within a few centimeters, the flea initiates a jump. The hind‑leg coxae store elastic energy in a protein called resilin; a rapid release produces an acceleration of up to 100 g, propelling the flea up to 18 cm vertically and 30 cm horizontally. This catapult mechanism enables the parasite to traverse gaps between host and environment.
Contact with the host’s fur triggers the claws on the tarsal segments, anchoring the flea. The insect then orients its head toward the skin and inserts the stylet—a composite of a serrated maxilla and a needle‑like mandible. The maxilla cuts through the epidermis, while the mandible creates a channel for saliva injection.
Saliva contains anticoagulants (e.g., apyrase) and anti‑inflammatory compounds that prevent clotting and reduce host detection. Blood is drawn through the stylet by a combination of capillary action and muscular pump. A single feeding bout may last several minutes, delivering up to 0.5 µL of blood per minute.
During ingestion, the flea can transmit pathogens present in the host’s blood. Common agents include Yersinia pestis (plague), Rickettsia spp. (murine typhus), and Bartonella spp. (cat‑scratch disease). The inoculation occurs when saliva mixes with the wound site, facilitating bacterial entry.
The entire assault can be summarized as follows:
- Detect host cues (heat, CO₂, vibration).
- Execute a high‑velocity jump toward the host.
- Secure attachment with tarsal claws.
- Penetrate skin using stylet apparatus.
- Release anticoagulant‑rich saliva.
- Ingest blood while potentially transmitting pathogens.
Host grooming, scratching, and the use of repellents represent the primary defensive measures against this parasitic attack.