Re: Flatworm? from Malaysia

Dear Michelle & Jeffree,
I'm glad you has some other photos, as this animal is very interesting - and definitely not a flatworm. It looks quite like a Sea Hare, but the presence of a distinct headshield suggests it is a some type of cephalaspidean bubble shell, perhaps in the family Aglajidae or Phlinidae. The parapodial flaps are very large, as are the 'tails' arising from the posterior end of the posterior (visceral) hump. I presume there is an internal shell over the visceral hump, as I think its edge is visible in your photos [see labeled photo]. I also think there is a large hole [foramen ] into the shell cavity, which is unusual in aglajids. A small pore has been reported in some species of Philine, and a small pore, or a larger foramen, is present in species of the Sea Hare genus, Aplysia [see Fact Sheet on aplysiid mantle cavity]. One other animal that apparently has such a foramen is Noalda exigua but it was described from a shell alone and I don't know if the one drawing of the live animal available is correctly identified [see message #6151]. Nothing is known of the anatomy of Noalda, but it has been suggested that it is an aglajid.  

Without any anatomical information I can't say much more. I'll call it Aglajid sp. 6. so we have something to call it in discussions. 
Best wishes,
Bill Rudman