• Ragini Mahajan

A claw-some species

As the name suggests, the Asian Small-Clawed Otter (Aonyx cinereus) is the smallest of all otter species and inhabits parts of Asia, like Indonesia, southern India, China, and the Philippines. As semiaquatic mammals, they call rivers, streams, and even mangroves home. To facilitate life underwater, these otters are able to close both their nostrils and ears while swimming! [1]


Uniquely, Asian small-clawed otters use the webbing between their toes to locate and trap food instead of their mouths. Despite the small size of their paws, these otters are able to crush the shells of crabs and mollusks with their paws. When that isn’t possible, they cleverly wait for the heat from the sun to break open the shells and access the meat [2].


This is especially different from their otter relatives, like the Northern River Otter (Lontra canadensis), who exclusively capture prey using their mouths! (You can learn more about the Northern River Otter in a previous blog post.)


Photograph by Jen Zoon, Smithsonian’s National Zoo [CC BY-NC-ND 2.0], via flickr.com

Asian small-clawed otters are heavily social, and typically exist in groups of 15-20 individuals. If you are ever around a family of these otters, you are likely to hear their many sounds, used for greeting, play, contact and alarm, as they are an extremely vocal species! Although this hasn’t been formally studied, many agree that they are incredibly otterable and very camera-friendly!


Sadly, Asian small-clawed otter populations have been slowly declining as a result of pollution, loss of habitat, and hunting. Which is why they are now considered a Vulnerable species by the International Union for Conservation of Nature (IUCN) [3]. Given that the biggest threat to their populations is loss of habitat and prey from pollution, there are simple things we can do to help this species. According to the Smithsonian, practicing the 3-Rs: Reduce, Reuse, Recycle (in that order), is an effective way of decreasing pollution and disturbance to the habitats of these Asian small-clawed otters. [4]


Today, we release the chromosome-length assembly for this otterly cute species. This is a de novo $1K genome assembly with contig N50 = 69 kb and scaffold N50 = 131 Mb. See Dudchenko et al., 2018 for details on the procedure.


For this genome assembly, we have used two samples from our collection. For DNA-Seq, the used blood donated by Hope, the small-clawed otter at the Houston Zoo. (Read more about Hope and her partner Danh Tu in this post by the Houston Zoo.) A blood donation from another otter, from San Antonio Zoo, was used to generate the Hi-C data for chromosome-length scaffolding. Thanks!

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