2015 Photo Contest, Nature, 1st prize



Anand Varma

National Geographic

01 August, 2013

Hyalella azteca, a tiny amphipod, lives at the bottom of lakes and ponds. Amphipods that have been invaded by the larva of a thorny-headed worm abandon the dark safety of the depths and swim to the surface. For the amphipod, this journey proves fatal, as it is a favored food of waterfowl, but for the larva (turned orange by pigments taken in from the host’s tissue) it is essential. Thorny-headed worms can grow to maturity only in the gut of waterfowl.

Many parasites not only feed off their hosts, but appear to manipulate the host’s behavior in a way that is advantageous to the parasite’s life cycle. Recent research indicates that this influence occurs at a genetic level—certain parasite genes seem to be able to take control of the host’s brain. Research has shown that in some cases a single parasite gene is responsible for altering the host’s behavior, though in most instances it is thought that the phenomenon is brought about by a combination of genes.

About the photographer

Anand Varma

Anand Varma is a freelance photographer and videographer who grew up in Atlanta, Georgia. He started photographing natural history subjects while studying biology at the Universi...

Technical information

Shutter Speed
Focal length
65.0 mm
Canon EOS 5D Mark III

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