Mountain streams are an oasis for most animals foraging in the hot summer including people visiting nature; a place where you can feel the breeze and cool yourself. Whenever you come close to the stream, you may find a tiny animal chilling underneath🤿. The Hong Kong Newt, 𝘗𝘢𝘳𝘢𝘮𝘦𝘴𝘰𝘵𝘳𝘪𝘵𝘰𝘯 𝘩𝘰𝘯𝘨𝘬𝘰𝘯𝘨𝘦𝘯𝘴𝘪𝘴 (Myers & Leviton, 1962) can be found in Hong Kong with its distribution range including Guangdong Province as well. While 20+ species of frog and toad species are encountered in the SAR, the Hong Kong Newt is the only Caudata species (amphibian with developed tail and limbs of similar length) species living here🧐.
The newt is brown-orange and 14-15 cm long. There are tiny dark brown or black bumps all over the body. On their belly, there possess patches of orange 🟠 markings, with those patterns unique to each individual, just like human fingerprints. Their forelimbs have 4 fingers (digits), but their hindlimbs have 5 fingers (digits). Another special feature is the presence of a red stripe along the ventral border of their tail. Their ecology is different from salamanders who spend most of their time on land, the newts prefer spending most of their time in the water. With a developed paddle-like tail and webbed feet, they are able to travel through the water effortlessly🏊♂️.
Their diet includes Brotia snails, Caridina shrimp, baetid mayflies, and calamoceratid caddisflies. Surprisingly, cannibalism is also very common (up to 25% of their diet), in particular in females which eat their own eggs and even the juveniles (larvae). There are several reasons proposed to explain this conspecific cannibalism behaviour (consuming individuals of the same species). Larvae and eggs are super nutritious, and represent the best and most accessible food source for female newts after the exhausted reproduction process🤰. Also, parents may consume decaying or infected eggs, to focus their parental care on the remaining eggs of better quality. Hence, with limited resources shared with fewer children, their offspring have better chances to survive. Another possible reason proposed to explain this cannibalism is to limit competition by eating eggs of other individuals. However, this explanation does not seem well supported in the case of the Hong Kong Newt.
In the wild, Hong Kong newts are not to be trifled with. When threatened or attacked, they release a toxin named Tetrodotoxin to fight off the predators. Tetrodotoxin has been studied in some pufferfish species and is believed to cause respiratory failure when exposed. Regardless of being lethal to us or not, we should always keep our distance and respect them in the wild😉. In addition, they warn potential predators by showing their brightly contrasting orange colour on the belly, as a signal of their toxicity or distastefulness. So if you observe the streams of Hong Kong, do not disturb them.
We are lucky to have this species preserved within the collection of the HKBM and here you can watch them up close.
Text: Ngai Long Ching
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