a larva from a Polychaeta

[Franz Neidl]

This is a planctonic larva from the Sabellidae (fan worms or feather duster worms) maybe Sabellaria alveolata (?). The lenght of the animal is 500 µm.

I would be happy to know what are the yellow spots (symbiotic algae?).

First picture: Obj. 10x, DIC.
Second picture: Obj. 20x, DIC.

Franz

[BJ]

hello Franz,

just a quick posting,

the yellow orange patches are made of of oil filled cells - of the worm itself. The pigment is a carotenoid pigment (ie of the carotene family - probably a xanthophyll) dissolved in the oil. In adult sabellids the pigment is often some form of astaxanthin (the pigment in salmon, lobsters etc).

I guess the function may be to help the larva orientate itself in relation to light ( in the ocean, brightest direction = "up").

here is a paper on sabellid larval development:

http://jcs.biologists.org/cgi/reprint/s3-93/24/435.pdf

I am enjoying all your posts..thank you !
kind regards
Brian