A Rock Louse, Ligia occidentalis.

This poor fellow made the mistake of trying to over winter in a tote that contained our artificial Christmas tree and couldn’t find its way out. The tote was in a crawl space the floor of which is granite that extends to the ocean meters away. A short “crawl” for this fellow when it is warmer. I have tried unsuccessfully to take photos of them before but they are too quick for me quickly disappearing into a crack in the rocks. This fellow was quite large, about 3.5cm!

comments (5)

Ferdy Christant

Lion

Awesome species intro, Gary, and a great shot. Indeed hard to capture, so yours joins our pretty small group, adding a brand new family to it:
https://www.jungledragon.com/wildlife/browse/animalia/arthropoda/malacostraca/isopoda Posted 6 years ago
1. gary fast
  
  Lion
  
  Thanks, Ferdy. I am still trying to collect info on this specific species. Not all that much to be found unless one dives into the scientific journals. Posted 6 years ago

gary fast

Lion

This Rock Louse is literally “a fish out of water” and should be somewhere moist so it can keep its gills moist. I was surprised to learn that in theory L. occidentalis is not supposed to be north of California but considering the length of its uropods (the forked tail parts) it is definitely a L. occidentalis and not a L. pallaisi. In L.occidentalis the uropods are greater than 1/3 the body length (which these are) and in L. pallaisi they are much shorter. This isopod spends a lot of time hidden in crevices and becomes more active later in the day foraging till dawn. It feeds on marine algae and diatoms. Their chromatophores allow them to become a lighter colour when it gets dark. Posted 6 years ago
1. Pudding4brains
  
  Lion
  
  Nice intro Gary! :o) The chromatophores in "our" Rock Slater (Ligia oceanica) are actually rumoured to allow the critters to change colour depending on the background colour of the substrate (for camouflage supposedly) ... unusual feature in Woodlice.
  Cheers, Arp
  PS. ... hmmm ... do we actually already have Ligia oceanica here? ... (edit) ... nope ... will see about that ...
  P.P.S. Okay ... added some:
  
  Posted 6 years ago, modified 6 years ago
2. 1. gary fast
    
    Lion
    
    Thanks Arp, have to admit that most of the times I have seen our local Ligia they have been “dark”. When the weather is a little more comfortable I’ll have to go with a light and check the night time coloration. Gary Posted 6 years ago