What does hemolymph mean?
Hemolymph is the circulating fluid found in most invertebrates, particularly insects, arachnids, crustaceans, and many mollusks. It performs several functions associated with vertebrate blood, including transporting nutrients, hormones, and metabolic wastes, while also contributing to immune defense. Unlike vertebrate blood, hemolymph is usually not colored red by hemoglobin; where respiratory pigments are present, they may be dissolved directly in the fluid or contained within specialized cells. The substance can be sampled from an animal and analyzed in laboratory studies of physiology, development, disease, and environmental stress. In ordinary English, the term is technical rather than everyday, and its use indicates a biological or comparative-anatomical context. It is especially useful for understanding the diversity of circulatory systems and for describing the internal environment of invertebrates without incorrectly applying the familiar features of vertebrate blood.
nounThe circulating fluid of most invertebrates, especially arthropods, functioning in a manner broadly comparable to vertebrate blood. It transports nutrients, hormones, and waste products and may contain cells associated with immune defense.
- The circulating fluid of most invertebrates, especially arthropods, that transports nutrients, hormones, and waste products and participates in immune defense.
"The insect's hemolymph circulates nutrients and defensive cells throughout its body."
"Researchers measured the composition of the crayfish hemolymph to assess its immune response."
"In a spider, hemolymph enters the prosoma and is pumped through the appendages by the heart."
The plural is used when referring to fluid samples from multiple animals or to distinct circulatory fluids; in general discussion, the noun is normally used as a mass noun.
"The researchers compared hemolymphs collected before and after the heat treatment."
An insect's 'blood' is not a simple liquid: its hemolymph can carry nutrients, hormones, waste, and immune cells through a body that has no lungs.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hemolymph come from?
The word is a compound of Greek haima, meaning “blood,” and Latin lympha, meaning “water,” a term historically associated with lymph and other body fluids. The modern form developed during the nineteenth century as zoologists sought a precise name for the circulating fluid of invertebrates. Its components also appear in cognates and related formations such as hematology, hemoglobin, lymphatic, and lymphocyte.
How hemolymph is actually used
A technical biological term, used chiefly in zoology, entomology, and comparative physiology. It should not be used as a general synonym for vertebrate blood, although that analogy is common in introductory explanations.
Easily confused with hemolymph
Lymph is a tissue fluid in vertebrates, whereas hemolymph is the circulating fluid of many invertebrates and also contains cells and substances involved in immunity.