Goldilocks and the Water Bears by Louisa Preston

Author:Louisa Preston
Language: eng
Format: epub
Publisher: Bloomsbury Publishing

Nature’s Superheroes – the Water Bears

The epitome of a polyextremophile and the kings (or queens) of surviving extreme environments, tardigrades are incredibly endearing, eight-legged, all-but-indestructible and mainly microscopic animals. First named tardigrada from the Latin meaning ‘slow walker’, they are also known as water bears (a name I love, derived from their resemblance to eight-legged pandas) and even moss piglets (drawing comparisons to pygmy rhinoceroses and armadillos). Most tiny invertebrates dart about frantically but the water bears see no need for this; they shuffle along slowly, clambering across bits of debris, ambling around their habitats on pairs of short, stubby legs located under their bodies. The legs are outfitted with a number of hooked claws that resemble the talons of bears. Water bears have five body sections, including one that is obviously a head (with or without a pair of eyes) and are encased in a rugged yet flexible cuticle that must be shed as the organism grows. Animals generally grow by adding more cells or by making each cell larger. The water bears for the most part do the latter, as they must must break out of the cuticle in order to grow. All of this houses a nearly translucent, charismatic miniature creature only half a millimeter in length, about the size of the full stop at the end of this sentence.

These mostly microscopic aquatic animals can be seen with the naked eye in the right light and are found just about everywhere across the Earth, from the Arctic to the Equator, from freshwater droplets within garden moss to the salty deep ocean, and to the tops of forest canopies and the summits of mountains. The vast majority of water bears feed only on plant cells or bacteria, slicing them open with their dagger-like teeth and drinking their fluid contents. Others, however, are vicious predators. Moving incredibly fast on the first six legs, they employ their fourth pair to stand upright and attack prey with the rest of their claws – not unlike an actual bear.

The ubiquity of water bears is linked to their best-known feature, their survivorship – they have survived all five mass extinctions – quite possibly because of their strong determination to overcome a cacophony of spectacularly extreme conditions. This has earned them the title of the most extreme survivor of all, beating penguins in Antarctica, camels in the desert and the common cockroach. Only the land-dwelling water bears can boast this title however; marine and aquatic species appear to not have developed these superhero characteristics. All the survival adaptations water bears display were selected in response to their rapidly changing terrestrial-based micro-environments. Terrestrial water bears, for example, technically live on the land but actually reside within thin films of water. Moss and lichens, for example, provide sponge-like homes dissected by a myriad of small pockets of water for water bears to inhabit, but are always at risk of drying out. The water bears have two choices in this situation – die or adapt to new, drier environmental conditions.

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