What do lice have in common? - briefly
All lice are obligate ectoparasites that survive only on the blood or skin debris of their specific hosts, possessing a flattened body and clawed legs. Their development follows a uniform three‑stage life cycle: egg, nymph, and adult.
What do lice have in common? - in detail
Lice are obligate ectoparasites that share a suite of anatomical, physiological, and ecological traits enabling them to survive on the bodies of warm‑blooded vertebrates. Their bodies are flattened laterally, a morphology that allows movement through hair or feathers while maintaining close contact with the host’s skin. The exoskeleton consists of a hard chitinous cuticle, providing protection against mechanical damage and desiccation.
All species possess chewing mouthparts adapted for extracting blood, skin cells, or sebaceous secretions, depending on the taxonomic group. Salivary enzymes contain anticoagulants that prevent clotting during feeding, facilitating continuous blood intake. Sensory organs are reduced; compound eyes are absent, and antennae are short, reflecting a lifestyle that relies on tactile cues rather than vision.
Reproductive strategies converge on viviparity. Females retain developing embryos within a specialized brood chamber, releasing fully formed nymphs that are immediately capable of feeding. This eliminates a free‑living larval stage and reduces exposure to environmental hazards. Gestation periods vary from a few days to weeks, but the overall life cycle—from hatching to reproductive maturity—generally completes within one month under optimal conditions.
Host specificity is a common feature. Each lice species is adapted to a particular host species or a closely related group, exhibiting coevolutionary patterns evident in genetic studies. This specialization includes preferences for specific body regions, such as the scalp, pubic area, or feather shafts, where microclimate conditions match the parasite’s physiological requirements.
Key shared characteristics can be summarized:
- Lateral body compression and a robust exoskeleton
- Chewing mouthparts with anticoagulant saliva
- Reduced visual and olfactory structures, reliance on tactile perception
- Internal development of embryos (viviparity) and direct birth of mobile nymphs
- Strong host specificity and region‑focused colonization
These convergent traits define lice as a distinct group of highly adapted ectoparasites, reflecting evolutionary solutions to the challenges of living permanently on a living host.