Despite the odds, life inhabits practically every inch of Earth. “That’s the marvelous thing,” said ichthyologist John Sparks, who along with parasitologist Mark Siddall cocurated the exhibit “Life at the Limits: Stories of Amazing Species” on display at the American Museum of Natural History (AMNH) in New York City. “Life is so tenacious; it’s resilient; it’s resourceful, and every place it can live, it does, basically. Every habitat we’ve looked at, from the top of the Himalayas to the bottom of the ocean trenches, from boiling hot springs to deep sea vents—there’s life there.”
The exhibit, which opens tomorrow (April 4) in AMNH’s LeFrak Family Gallery, explores the diversity of life at Earth’s extremes of temperature, pressure, wetness, and aridity—and everywhere in between. The exhibit also highlights the range of adaptations that creatures have experienced in order to thrive in myriad conditions. As it turns out, different creatures solve similar problems in different ways. Take egg-laying: corals release millions of egg and sperm in synchrony under the full moon, while the pregnant kiwi bird waddles around carrying one giant egg, which can grow to a quarter of her body weight. Which strategy is best? Both of them work well under the right circumstances.
While most creatures featured in the exhibit have adapted to one extreme or another, the tardigrade, the tiny animal whose scaled-up models hang from the ceiling at the gallery’s entrance, can withstand environmental extremes of all sorts. This creature, called the water bear, is about the size of a poppy seed and has a round body, eight legs, and a round protruding snout that makes it look like a caterpillar in a gas mask. When conditions are unfavorable, the water bear forms a spore-like like state that can survive boiling, freezing, high pressure, and the vacuum conditions and radiation levels of outer space. When conditions improve, it reanimates itself.
“We think that its ability to withstand a lot of different things really comes down to the same thing, and that is the ability to survive desiccation,” said Siddall. “The ability to survive the removal of water . . . is something that makes it resistant also to freezing and to boiling and to radiation.”
This astounding creature, the exhibit’s poster child, may have been missed without the aid of rigorous research (and microscopy).
Asked during a press conference how the study of extremophiles on Earth might inform researchers about the possibility of life on other planets, Siddall replied: “that kind of research . . . expands the range of possibility of where we might find life [beyond Earth], should we find it one day.”