A Colorful Land Planarian is Found in New Caledonia - Observation of the Week, 10/28/19

Our Observation of the Week is this Australopacifica sarasiniana land planarian, seen in New Caledonia by @damienbr!

“I'm working as a software engineer and spend my free time in nature,” says Damien Brouste, a resident of New Caledonia. Damien focused on underwater photography for several years (check out one of his photos of coral under UV light here), until “my boat get caught in a tempest earlier this year. So I had to find a new hobby. That's when I discovered the magic of the New Cal forest by night.”

The difference between night and day is amazing. I used to hike, and only experienced the forest by day. It was hard to find any life. Everything changes when the night comes. [The forest] comes alive. Even the sounds are completely different. It can be dead calm during the day, and all the cicadas and crickets start to sing when the light goes down...So, I started to make trips into the forest by night.

Damien soon started a naturalist group in New Caledonia, where members exchange their photos and plan weekly trips together. It was on one of these trips that Damien came across the brightly colored worm you see above.

One of my friends was looking for geckos (eyes up), another for arachnids (eyes middle) and I was looking for small arthropods (eyes down)....You can't miss a planarian with those striking colors. It was the third individual (of this species) I found, but I still decided to take pictures as it had a nice posture...Differences can be really small between species. 

Then this observation was chosen as the Observation of the Day. That's when I got an ID for it.

The identifier of Damien’s observation was user @leigh_winsor, one of iNat’s top identifiers of land planarians. Leigh has been working with land planarian systematics and taxonomy, much of it in his free time, for 47 years! 

“Now I am retired I can really indulge my passion with land planarians,” says Leigh. 

Identifying specimens on iNaturalist (I did this also for the Australian website BowerBird before it closed and transferred to iNaturalist) is particularly interesting as you can often see photos of live specimens of species with which you are familiar that were originally described from preserved specimens - a special thrill! Also provides me with more time to taxonomically revise various species and genera of land planarians, particularly those in the Australian Region.

Land planarians are flatworms which have adapted to terrestrial life, moving about on their “creeping sole,” which is covered in tiny cilia. They are carnivorous, and most prey on other terrestrial invertebrates, feeding on them with the pharynx located near the middle of their bodies. The pharynx is able to produce digestive juices that begin to digest the prey outside of the worm’s body. Leigh tells me that not much is known about this particular species, aside from the fact that it was described in 1924 by Schroder, and it’s one of 23 recorded species in New Caledonia and the Loyalty Islands

“I have gotten great help from the iNat community in identifying my pictures,” says Damien (above, after a dive in an underwater cave), “and it's very easy to find an expert which can help you to identify your find. iNat gives me a more scientific approach to my observations, and identifications are way easier. Image recognition is a nice tool, it just needs more data from New Cal. That's why I encourage my friends to use it.”

Some quotes have been lightly edited for clarity and flow.

- This video depicts a land planarian capturing several types of prey, it’s pretty impressive.

- Leigh Winsor published this paper describing a new genus and species of land planarian, part of a collaboration with ORSTOM and MNHN.

Posted on October 29, 2019 04:07 AM by tiwane