What are fleas and how do they look? - briefly
Fleas are tiny, wingless insects that parasitize mammals and birds, extracting blood for nourishment. They are laterally flattened, reddish‑brown, 1–3 mm in length, and possess powerful hind legs enabling rapid jumps.
What are fleas and how do they look? - in detail
Fleas are small, wing‑less insects belonging to the order Siphonaptera. They are obligate ectoparasites that feed on the blood of mammals and birds. Adult females can ingest up to ten times their body weight in blood each day, which supports rapid reproduction; a single female may lay several hundred eggs during her lifetime.
Morphologically, fleas measure 1–4 mm in length, with a laterally compressed body that facilitates movement through host fur or feathers. Their exoskeleton is hardened (sclerotized) and covered with a fine layer of microscopic spines that increase grip on the host’s skin. The head is small, equipped with powerful mandibles for piercing skin and sucking blood. Antennae are concealed beneath the head capsule, rendering them invisible without magnification.
Key anatomical features include:
- Jumping legs: The hind femora are enlarged, containing elastic protein (resilin) that stores energy for leaps up to 150 times body length.
- Sensory organs: Compound eyes are reduced; instead, the flea relies on a pair of long antennae and sensory hairs to detect heat, movement, and carbon dioxide.
- Digestive system: A specialized foregut allows rapid ingestion of blood, while the midgut secretes enzymes that break down host proteins.
- Reproductive organs: Females possess a large abdomen that expands as eggs develop; eggs are laid in the host’s environment, not on the host itself.
Coloration ranges from reddish‑brown to dark brown, varying among species. The dorsal surface often appears glossy due to a thin waxy coating that protects against desiccation. The abdomen may display a subtle banded pattern in some species, aiding identification under a microscope.
Life cycle stages—egg, larva, pupa, and adult—are distinct. Eggs are laid on the host’s bedding, hatch into worm‑like larvae that feed on organic debris, and spin cocoons in which pupation occurs. Environmental cues such as vibrations or increased carbon dioxide trigger emergence of the adult flea from the cocoon.
Understanding these physical characteristics and biological processes is essential for accurate identification and effective control measures.