page_title: Rakali
section_title: Diet and foraging
hierarchical_section_title: Rakali / Ecology / Diet and foraging
caption_attribution_description: English: Collage Helminth eggs: these eggs are of big medical importance, and are widely distributed worldwide, when they grow and get to the adult state (worms), they cause over 3 billion human infections around the world.
context_page_description: The rakali, Hydromys chrysogaster, also known as the rabe or water-rat, is an Australian native rodent first described in 1804. The change to the aboriginal name Rakali was intended to foster a positive public attitude by Environment Australia. The Gunwinggu people of western Arnhem Land call this animal Yirrku.
  It is the only member of the genus Hydromys with a range extending beyond Papua New Guinea and Indonesian West Papua. Having adapted to and colonised a unique niche of a semiaquatic and nocturnal lifestyle, this species lives in burrows on the banks of rivers, lakes and estuaries and feeds on aquatic insects, fish, crustaceans, mussels, snails, frogs, birds' eggs and water birds. Rakali have a body 231–370 millimetres in length, weigh, 340–1,275 grams and have a thick tail measuring around 242–345 millimetres. Females are generally smaller than males but tail lengths are normally the same.They have partially webbed hind legs, waterproof fur, a flattened head, a long blunt nose, many whiskers and small ears and eyes.
context_section_description: Rakali are a predominately carnivorous species feeding on a variety of aquatic animals including fish, crustaceans, shellfish, small birds, eggs, mammals, frogs, reptiles. In winter, when resources are limited, they will also take plants. A mostly nocturnal species, they search for their food on dusk, partly by sight when in the water and hunting prey on the waters edge returning to a favourite feeding place where evidence of previous catches can be seen. They can be found swimming and feeding in the early morning and evening. The animal does not tolerate low temperatures well, so they prefer terrestrial prey in winter over the aquatic species. They also spend long periods in the warmth of the burrow. A relatively new addition to their diet is the hearts and livers of the toxic cane toad, where the toads have moved into their territory.
  Their diet makes this species susceptible to infestations of nematodes, with large numbers of Cosmocephalus australiensis recorded in 1959 burrowed into their stomach walls. Other worms namely Cestodes and trematodes occur in high numbers in the small intestines. Sparganosis also afflicts rakali, these parasites coil under the skin surface in the shoulder and back region. The extent of infestation and the varieties of Helminth that are present reflects the region which they inhabit.
caption: Helminth: various species of worms that infest water rats
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