How do Spanish Dancers reproduce?

September 7, 2000
From: Leticia I.

To whom it may cooncern,

Hello my name is Leticia from Hawaii. Our class is doing research on invertebrates and vertebrates. Each group had to pick one of each. My group chose a Hawaiian Monk Seal for our vertebrate and for an invertebrate we choose a Spanish Dancer (Hexabranchus sanguineus). I found info about it's habitat and diet but for some reason I can't find info on how it reproduces.
Can you help me?


Leticia I., 2000 (Sep 7) How do Spanish Dancers reproduce?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Leticia,
You certainly chose a spectacular invertebrate to study. Have a look at all the messages and photos of Hexabranchus above and below your message. You will find quite a lot of information there. If you are able to visit a library that has the scientific journal The Veliger there is a very good article which has all the information you would need:
• Francis, M.P. (1980) Habitat, food and reproductive activity of the nudibranch Hexabranchus sanguineus on Tongatapu Island. The Veliger, 22(3): 252-258.

Perhaps your teacher or one of your parents could help you find it, as The Veliger is an American scientific journal which most museums and university libraries should have.

Basically all sea slugs are hermaphrodite. That is they have a full set of male and female organs. They don't fertilise their own eggs however, but every time they mate they are able to give and receive sperm, so doubling their opportunity to pass on their genes. They lay a large frilly pink egg mass with thousands of tiny eggs which hatch out as free-swimming veliger larvae, which swim for some time in the plankton before settling down and turning into tiny crawling slugs. Use the SEARCH button to find information on veligers [type veliger]. You will also find a photo below of a very small Hexabranchus which looks quite different from the adults, and is unable to swim.

I hope this will help you with your project. Have a look at some of the General Topic pages for some more information on nudibranchs.

Good Luck with your project,
Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (Sep 7). Comment on How do Spanish Dancers reproduce? by Leticia I.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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