The Invertebrate Heart
In invertebrates that possess a circulatory system, the heart is typically a tube or small sac and pumps fluid that contains water and nutrients such as proteins, fats, and sugars. In insects, the "heart" is often called the dorsal tube and insect "blood" is almost always not oxygenated since they usually respirate (breathe) directly from their body surfaces (internal and external) to air. However, the hearts of some other arthropods (including spiders and crustaceans such as crabs and shrimp) and some other animals pump hemolymph, which contains the copper-based protein hemocyanin as an oxygen transporter similar to the iron-based hemoglobin in red blood cells found in vertebrates.
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Famous quotes containing the word heart:
“Although the stupid, unthinking world may approve what you have done, in your heart you know that, but for your treachery, the boy you loved would be alive today. If anyone is responsible for his death, you killed him, and for that murder you will live and die in the contempt and loathing of your own heart.”
—Karl Brown (1897–1990)