What does a mosquito's heart look like? I would never have expected that it would look like this, a fluorescent image taken by Jonas King, a student at Vanderbilt University, which won first place in the Nikon Small World photography competition.

King, working in the lab of biologist Julián Hillyer, took the image as part of research into the circulatory system of one of the species of mosquitoes that spread malaria, Anopheles gambiae. The green dye illuminates the heart's muscle cells while the blue dye marks the DNA inside all the cells.

A mosquito's heart isn't like ours. For one, it pumps a clear liquid called hemolymph, usually towards the head but sometimes in the opposite direction. The heart takes up around two-thirds of the insect's entire circulatory system, which is just a long tube that runs from its head to its tail (the long tube in the middle of the photo). The heart works like a series of valves that pump by expanding and contracting. The triangular shaped structures in the photo hold the heart to the mosquito's back.

Hillyer says that learning more about the mosquito's circulatory system and its role in spreading the malaria parasite could help in developing strategies to control the disease.

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