How does this small brown crescent-headed land planarian(?) "look around" and sense its envirnoment?

Question

This 2-3 cm long, thin brown worm with a wide "anchor" or hammer or crescent shaped head was seen in northern Taiwan slowly moving along a damp tile outdoor surface. It moved by contraction/extension and regularly lifted its head appearing to explore its environment, as if to say "where should I go next"?

Comments suggest that this is a land planarian.

Question: Is it possible to confirm that this is a land planarian and to understand what sensory organs it has on its head in order to "look around" and decide where to go next?

@theforestecologist yes, it does indeed look like a land planarian and the hammer-shaped head was my first clue, thanks! (see also here from here) So all that's left now is the part about how it senses its environment. — uhoh, Feb 16 '21 at 03:08
Edited to reinforce that this is not a duplicate because what's still asked here is the part about how it senses the environment — uhoh, Feb 17 '21 at 19:33

score 1 · Accepted Answer · edited Feb 18 '21 at 00:57

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Given that "hammerhead worms" are Bipaliinae, I expect you can find your species from this bibliography¹. Bipalium or Diversibipalium ruteofulvum and cosmopolitan Bipalium kewense are mentioned, but I did not find images of these species online just now.

A paper about the sense organs of B. kewense (Abdel-Haleem, 2014) mentions many small pigment cup eyespots, as well as papillae and pits that may be chemosensory in nature.

¹Kawakatsu et al. 2004 An Annotated Bibliography of Taiwan Land Planarians, with Lists of Linked Papers on This Animal Group

edited Feb 18 '21 at 00:57

uhoh

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answered Feb 17 '21 at 22:32

Mike Serfas

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Thanks for your answer! The historical bibliography is intriguing, and also provides a historical view to the colonial rule period. – uhoh Feb 18 '21 at 01:08

How does this small brown crescent-headed land planarian(?) "look around" and sense its envirnoment?

1 Answers1