Mating Clione limacina (Philipps, 1774)

• Main Authors: Boxhammer, Tim, Sswat, Michael, Kohnert, Peter, Schrödl, Michael, Riebesell, Ulf
• Format: Report
• Language: English
• Published: GEOMAR 2017
• Subjects: Arctic; Kongsfjord; Svalbard; Clione limacina; Kongsfjord*
• Online Access: https://dx.doi.org/10.3289/mating_clione_limacina_2010; http://oceanrep.geomar.de/38574/

In July 2010 the authors observed two mating specimens of Clione limacina (Phipps, 1774) in the surface water of the Arctic Kongsfjord, Svalbard (78° 57.6564’ N, 12° 2.55558’ E). Clione limacina is a holopelagic gastropod mollusc that belongs to the monophyletic group Pteropoda, which members are characterized by the possession of paired, wing-like appendages. These "wings" constitute a modified gastropod foot and are used for active swimming. Two subgroups of pteropods exist, the shelled Thecosomata and the unshelled Gymnosomata. Gymnosome species are hard to study for a variety of reasons and thus our knowledge on these animals is still very limited, in particular when it comes to behavioral observations. Here we present rare video footage of two mating specimens of Clione limacina, which have been transferred into a plastic bowl for closer observation. Specimens were facing each other on their ventral sides and kept swimming slowly during the whole period. The cephalic copulatory apparatus, which contains a long and slender accessory organ and a penis is everted in both specimens. The free accessory copulatory organs are wrapped around the partner and the penes are inserted into the mates’ posterior genital opening. The transfer of a spermatophore from the anterior male genital opening along the penis is clearly visible. Fertilization is reported to be reciprocal in this species. Although the mating process has been described previously, the functional physiology of involved anatomical structures (i.e. complex glandular systems) in the formation of the spermatophores and spawn remains obscure.