2015 Photo Contest, Nature, Stories, 1st prize

Mindsuckers

Photographer

Anand Varma

National Geographic

08 August, 2013

After the flatworm (Ribeiroia ondatrae) reproduces asexually inside a snail, its larvae find a bullfrog tadpole and burrow through its skin, forming cysts around the frog’s developing limbs. With legs added, subtracted, or compromised, the ungainly victim is easy prey for frog-eating birds like herons. Inside the heron, the parasite reproduces sexually. Its eggs re-enter the water when the bird defecates, infecting new snails to start another round.

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

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
1/200
Focal length
50.0 mm
F-Stop
16.0
ISO
3200
Camera
Canon EOS 5D Mark III

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