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:
“Only ambition is fired by the coincidences of success and easy accomplishment but nothing is quite as splendidly uplifting to the heart as the defeat of a human being who battles against the invincible superiority of fate. This is always the most grandiose of all tragedies, one sometimes created by a dramatist but created thousands of times by life.”
—Stefan Zweig (18811942)