Project 2877: J. A. Goodheart, S. Bleidissel, D. Schillo, D. L. Ayres, A. Preisfeld, E. E. Strong, A. G. Collins, M. P. Cummings, H. Waegele. 2018. Comparative morphology and evolution of the cnidosac in Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia). Frontiers in Zoology. 15:43.
Specimen: Dondice occidentalis (USNM:1276036)
View: cross section


A number of shelled and shell-less gastropods are known to use multiple defensive mechanisms, including internally generated or externally obtained biochemically active compounds and structures. Within Nudipleura, nudibranchs within Cladobranchia possess such a special defense: the ability to sequester cnidarian nematocysts – small capsules that can inject venom into the tissues of other organisms. This ability is distributed across roughly 600 species within Cladobranchia, and many questions still remain in regard to the comparative morphology and evolution of the cnidosac – the structure that houses sequestered nematocysts (called kleptocnides). In this paper, we describe cnidosac morphology across the main groups of Cladobranchia in which it occurs, and place variation in its structure in a phylogenetic context to better understand the evolution of nematocyst sequestration.

Overall, we find that the length, size and structure of the entrance to the cnidosac varies more than expected based on previous work, as does the structure of the exit, the musculature surrounding the cnidosac, and the position and orientation of the kleptocnides. The sequestration of nematocysts has originated at least twice within Cladobranchia based on the phylogeny presented here using 94 taxa and 409 genes.

The cnidosac is not homologous to cnidosac-like structures found in Hancockiidae. Additionally, the presence of a sac at the distal end of the digestive gland may have originated prior to the sequestration of nematocysts. This study provides a more complete picture of variation in, and evolution of, morphological characters associated with nematocyst sequestration in Cladobranchia.

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Article DOI: 10.1186/s12983-018-0289-2

Project DOI: 10.7934/P2877,
This project contains
  • 84 Media
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  • 117 Taxa
  • 55 Specimens
Total size of project's media files: 432 MB

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MorphoBank Project 2877
  • Creation Date:
    29 January 2018
  • Publication Date:
    26 November 2018
  • Project views: 7549


    member name taxa specimens media
    Jessica Goodheart
    Project Administrator
    Last logged in 11/26/18
    Sabrina Bleidi
    Last logged in 02/22/18
    Allen Collins
    Last logged in Never
    Michael Cummings
    Last logged in Never
    Dorothee Schillo
    Last logged in Never
    Ellen Strong
    Last logged in 02/18/18
    Heike W
    Full membership
    Last logged in 02/22/18

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    Total downloads from project34
    Document downloads3Data Matrix of Cnidosac Details (1 download); Data Matrix of Presence/Absence of Distal Sac and Kleptocnides (2 downloads);
    Project downloads31