A question about alabaster nudis . . .

[LCF]

I seem to remember having learned somewhere that they ingest nematocysts from their prey, and relocate them in their cerata for protection. Does anybody have a reference on this, or know whether it is true? A friend is writing an article, and would like to get it right.

[Tidepool Geek]

Hello,

I'm assuming that you're referring to Dirona albolineata. If that's the case then it most likely does not sequester nematocysts in the manner of the aeolid nudibranchs. Acccording to The Sea Slug Forum this species mainly eats bryozoans and other almost exclusively non-stinging prey. The site does mention them possibly eating hydroids but Dave Behrens once told me that they are probably specialists on bryozoans alone. Based on that, there would be little or no evolutionary opportunity for the species to develop the ability to sequester. Further, this species has a reputation for dropping cerata when attacked; such behavior would seem to be contra-indicated if the animal expected to use the cerata as an active defense.

Here's the link to this species on The Sea Slug Forum:
http://www.seaslugforum.net/find/diroalbo

This link may be a good start on the subject of nematocyst sequestration:
http://www.seaslugforum.net/find/defcnid

Sluggishly yours,
Alex

[Greg Jensen]

Dirona is equipped with a very impressive set of jaws that they use for crushing small snails, in addition to eating bryozoans.

[Tidepool Geek]

Hello again,

Unlike with many nudibranchs, defining the diet of this species is fraught with difficulties since they seem to be willing to eat whatever is available and within their abilities to capture.

Here's a link to a paper describing them eating snails:
http://scholarspace.manoa.hawaii.edu/bi ... sequence=1
[I wasn't previously aware of this paper but apparently neither was Mr. Behrens when he emphatically told me that these guys don't eat snails - go figure!]

Here's a link to a paper describing them eating bryozoans - but usually only certain parts of a given colony:
http://www.jstor.org/discover/10.2307/1 ... 1858152007

Finally, here's one about cogener Dirona aurantia eating anything except what it was "supposed" to eat - rather like a molluscan goat:
http://www.columbuszoo.org/drumcroaker/ ... df#page=44

Please note that none of the prey items mentioned have nematocysts.

Gourmandishly yours,
Alex

[LCF]

Thank you both -- great references! I had found the slug site comment on them not sequestering nematocysts, but that seemed contradicted by the mentions of eating hydroids. We took the comment out of the article, anyway.