Egg ribbons - flattened form in chromodorids


Egg ribbon of Cadlinella ornatissima from the Marshall Ids, showing egg ribbon attached on one side to the substrate. Photo: Scott Johnson.

Most chromodorid nudibranchs lay a typical dorid egg mass in which one edge of the flattened ribbon is attached to the substrate in a spiral. A few species have been reported to lay an egg mass in which one side of the ribbon is stuck to the substrate. This may be an interesting clue to phylogenetic relations in the family or it may have some function. This page is a place to record any records of this type of egg mass, preferably with photos. See Nerida Wilson's list below.

Listed below are observations on the Forum to photos of this type of egg ribbon with a link to relevant messages.

Cadlinella ornatissima
Chromodoris dianae
Chromodoris elisabethina
Chromodoris kuiteri
Chromodoris striatella
Chromodoris willani

Authorship details
Rudman, W.B., 2001 (January 8) Egg ribbons - flattened form in chromodorids. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Flat chromodorid egg masses

December 7, 2002
From: Nerida Wilson

Hi Bill,
After reading the recent message about Chromodoris dianae laying a flat egg mass, I thought I would bring to your attention my recent paper which identified several more species that lay similar egg masses. It is seems that this 'stripey' group of species probably forms a closely-related clade within Chromodoris.
Chromodoris aspersa
Chromodoris kuiteri
Chromodoris lochi
Chromodoris strigata

During my recent work in Sulawesi, I also can confirm more flat egg mass layers
Chromodoris annae
Chromodoris cf. colemani
Chromodoris cf. strigata
Chromodoris magnifica - C. magnifica had been previously published as laying an upright crenulated egg mass (Klussmann-Kolb & Waegele, 2001).

• Wilson, N. G. (2002). Egg masses of chromodorid nudibranchs (Mollusca: Gastropoda: Opisthobranchia). Malacologia, 44(2): 289-305


Wilson, N.G., 2002 (Dec 7) Flat chromodorid egg masses. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Nerida,
I thought you would be interested when I posted Mary Jane's message. I was of course aware of your interesting publication and am very grateful for you drawing everyone's attention to it. I would love to be able to notify everyone of interesting new publications as they appear but I just don't have time. Could anyone who wants to let us know about their recent work please follow Nerida's example and send a message to the Forum.

Returning to egg ribbons - I must say I wonder why one whole group of chromodorids would find it beneficial to lay flattened egg ribbons?
Best wishes,
Bill Rudman

Chromodoris elisabethina - 'flattened' egg ribbon

January 12, 2001
From: Scott Johnson

Hi Bill,

Thanks for the comments on the Cadlinella egg mass. Afraid I don't have any shots of this species actually putting down the eggs, but attached are two shots of Chromodoris elisabethina in the process. In the upper photo you can see the egg strand coming out of the reproductive opening and laying down flat. Then is seems the nudi ensures that it's flat by crawling over it. All the member of the "quadricolor" color group I'm familiar with have these kinds of egg masses, along with a few other differently colored species such as Chromodoris aspersa and a couple of as yet unidentifieds.


Johnson, S., 2001 (Jan 12) Chromodoris elisabethina - 'flattened' egg ribbon. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Scott,
Let's hope this discussion will alert some other eyes to look for other species of chromodorids laying these flat egg ribbons. I have started a special page to rcord this information.
Best wishes,
Bill Rudman.

Rudman, W.B., 2001 (Jan 12). Comment on Chromodoris elisabethina - 'flattened' egg ribbon by Scott Johnson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from