Rakali (Hydromys chrysogaster) lives in freshwater wetlands across Eastern Australia. It feeds on aquatic insects crustaceans. Its conservation status is Least Concern.
Fascinating facts about the Rakali
- Rakali have learned to avoid the cane toad's poisonous shoulder glands by flipping the amphibian onto its back before attacking, a behaviour that lets them handle the toxic prey safely. By turning the toad over they can bite the softer underside without contacting the glands. They also appear immune to any poison that might be ingested from the toad's skin, allowing them to eat the animal whole.
- In regions where cane toads have become abundant, rakali have added the toad's heart and liver to their diet, consuming these toxic organs without apparent ill effect. The toads, introduced in the early twentieth century, have exploded from an initial 100 individuals to as many as 100 million across Australia. Rakali's resistance to the toad's skin secretions lets them eat the organs safely, even though the amphibian's poison can kill other mammals.
- On land rakali can sprint at twice the speed they achieve while swimming, showing a dramatic shift in locomotor performance. Their metabolic rate rises by 13-40 % during running compared with swimming, meaning they burn more energy when they dash across the bank. Studies have shown they use less oxygen when moving on land than in water, highlighting the efficiency of their terrestrial bursts.
- A rakali's territory spans 1-4 km of waterway, yet it may cover 200 m to 1 km in a single night while hunting. Such nightly forays let it patrol a large stretch of its riverbank home.
- Among the four Hydromys species, the rakali alone reaches beyond New Guinea, inhabiting mainland Australia's rivers and lakes. Its distribution makes it the only genus member with such a wide range.
Sources
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At a glance
RangeEastern Australia
HabitatFreshwater wetlands
DietAquatic insects crustaceans
About the Rakali
In the moonlit shallows of Australia's coastal wetlands, the rakali, a water rat of uncommon elegance, glides effortlessly through the ripples, its sleek fur glistening like polished silk as it hunts for crustaceans and small fish with stealthy precision. With a twitch of its whiskers and a flick of its tail, it navigates the intricate network of mangrove roots and tidal creeks, a master of its aquatic realm. As it swims, the rakali's webbed hind feet propel it with a quiet power, leaving behind a trail of subtle disturbance in the otherwise glassy waters.
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