Tremoctopus gracilis (Eydoux & Souleyet, 1852) has tentacles of jellyfish to arms.

This time, I could shooting valuable male ecology of Tremoctopus gracilis (Eydoux & Souleyet, 1852) at Palau. That is probably of a third case in the world.

Tremoctopus gracilis is a very unique an octopus of open ocean-swimming with web on the arm. The male is very small compared to the female, So far, It's have been most captured in such investigation by the plankton net.

The first discovery is by David Paul of Melbourne University. It was the world's first ecological photographed at Great Barrier Reef, in Australia. after that, first report is by Dr Norman in 2002.
At that time, it has been reported to have the tentacles of cnidarians such as jellyfish. Then, that this species is holding tentacles at selectively Portuguese Man O' War (Physalia physalis) has also been re-reported at Tree of Life Web Project. So far, how to use of this jellyfish tentacles, it has been considered for the defense or attack.

Tremoctopus gracilis (Eydoux & Souleyet, 1852)　,male, ML:15mm

seems to be tentacles of Physalia physalis on the sucker arm.

Related report

Larva of Blanket Octopus
http://www.blackwaterdive.net/2016/01/larva-of-blanket-octopustremoctopus.html

REFERENCES:

Sweeney, M.J., Roper, C.F.E., Mangold, K.M., Clarke, M.R., and Boletzky, S. v. 1992. 'Larval' and juvenile cephalopods: a manual for their identification. Smithsonian Contributions to Zoology - No. 513. 282pp.

Norman, M.D. 2000. Cephalopods A World Guide. Frankfurt, Germany, IKAN Publishing. 320 pp.

Jereb,P., Roper,C.F.E.,Norman,M.D.,Julian,K.F., 2014. Cephalopods of the World. An annotated and illustrated catalogue of Cephalopod species known to date Volume 3 Octopods and Vampire Squids. FAO Species Catalogue for Fishery Purposes No.4, Vol.3. 382pp.

Tremoctopus - Tree of Life Web Project

Larva of Blanket Octopus,Tremoctopus gracilis (Eydoux & Souleyet, 1852) Tremoctopodidae.

This larva of a Blanket Octopus was taken at Omi Island Yamaguchi Prefecture Japan.
Omi Island is located in the Sea of ​​Japan coast of Yamaguchi Prefecture.

This larva of mantle length was about 4mm.
Mantle is translucent, brachial membrane envelops head and arms.
Ciliary process are lined to Mantle.

Lateral view

Among the larvae of the arm, dorsal arms is the most developed and the other arm is quite short.
Dorsal arms has very large suckers. Sucker is gradually to bigger from the tip, and the largest sucker is fourth from the tip. Web of arms is not yet developed.

Chromatophores present on inner edge of each sucker, and absent on funnel.
Orange large iridophores are arranged around the eyes.

Dorsal view

Mantle typically triangular in shape.

Dorsal mantle scattered with chromatophores.

ventral view

Large eyes are facing the ventral.

Ventral mantle patterned with a band of yellow from red chromatophores along anterior margin.

Other Notes;

Often, adult of Tremoctopus gracilis appear to Omi Island in late summer. Genus Tremoctopus are pelagic octopus that live on the surface to 250m. And also known to feed on Pteropod Molluscs and small fishes. Larva often known that hold on Physalia tentacles in arms I and II.

REFERENCES

Sweeney, M.J., Roper, C.F.E., Mangold, K.M., Clarke, M.R., and Boletzky, S. v. 1992. 'Larval' and juvenile cephalopods: a manual for their identification. Smithsonian Contributions to Zoology - No. 513. 282pp.

Norman, M.D. 2000. Cephalopods A World Guide. Frankfurt, Germany, IKAN Publishing. 320 pp.

Jereb,P., Roper,C.F.E.,Norman,M.D.,Julian,K.F., 2014. Cephalopods of the World. An annotated and illustrated catalogue of Cephalopod species known to date Volume 3 Octopods and Vampire Squids. FAO Species Catalogue for Fishery Purposes No.4, Vol.3. 382pp.

Tremoctopus - Tree of Life Web Project