Feeding on Fluids
Feeding on Fluids
Fluid feeding is especially characteristic of parasites, but it is practiced among many free-living forms as well. Some internal parasites (endoparasites) simply absorb the nutrient surrounding them, unwittingly provided by the host. Others bite and rasp host tissue, suck blood, and feed on the contents of the host’s intestine. External parasites (ectoparasites) such as leeches, lampreys, parasitic crustaceans, and insects use a variety of efficient piercing and sucking mouthparts to feed on blood or other body fluid. There are numerous arthropods that feed on fluids, for example, fleas, mosquitoes, sucking lice, bedbugs, ticks and mites, to name some of the more troublesome that assault humans as well as other vertebrate hosts. Many are vectors of serious diseases of humankind and thus qualify as far more than pesky annoyances.
Unfortunately for humans and other warm-blooded animals, the ubiquitous mosquito excels in its bloodsucking habit. Alighting gently, the mosquito sets about puncturing its prey with an array of six needlelike mouthparts (Figure 20-18B,). One of these is used to inject an anticoagulant saliva (responsible for the irritating itch that follows the “bite” and serving as a vector for microorganisms causing malaria, yellow fever, encephalitis, and other diseases); another mouthpart is a channel through which the blood is sucked. It is of little comfort that only the female dines on blood to obtain nutrients necessary for formation of her eggs.
Fluid feeding is especially characteristic of parasites, but it is practiced among many free-living forms as well. Some internal parasites (endoparasites) simply absorb the nutrient surrounding them, unwittingly provided by the host. Others bite and rasp host tissue, suck blood, and feed on the contents of the host’s intestine. External parasites (ectoparasites) such as leeches, lampreys, parasitic crustaceans, and insects use a variety of efficient piercing and sucking mouthparts to feed on blood or other body fluid. There are numerous arthropods that feed on fluids, for example, fleas, mosquitoes, sucking lice, bedbugs, ticks and mites, to name some of the more troublesome that assault humans as well as other vertebrate hosts. Many are vectors of serious diseases of humankind and thus qualify as far more than pesky annoyances.
Unfortunately for humans and other warm-blooded animals, the ubiquitous mosquito excels in its bloodsucking habit. Alighting gently, the mosquito sets about puncturing its prey with an array of six needlelike mouthparts (Figure 20-18B,). One of these is used to inject an anticoagulant saliva (responsible for the irritating itch that follows the “bite” and serving as a vector for microorganisms causing malaria, yellow fever, encephalitis, and other diseases); another mouthpart is a channel through which the blood is sucked. It is of little comfort that only the female dines on blood to obtain nutrients necessary for formation of her eggs.
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