Larval development in Doriopsilla gemela
November 23, 2005
From: Jeff Goddard
Hi Bill,
Here are some photos of Doriopsilla gemela from San Diego, California showing: (1) the color of the gills, (2) its flat egg mass, and (3) a hatching larva. The larvae I observed developed from eggs averaging 111 microns in diameter and hatched after 8.5 days (at 15-21 degrees C) with shells 173-184 microns long. They lacked both propodium and eyespots and were clearly planktotrophic.
Locality: Point Loma, San Diego, California, USA. Pacific coast. Intertidal. Length: 16 mm. 27 April 2005. Rocky intertidal. Photographer: Jeff Goddard
As I discussed in my recent review of developmental mode in the family Dendrodorididae, the report by Gosliner et al (1999) of lecithotrophic development in this species requires confirmation because (1) they did not describe the hatching larvae or give any measurements of its size, and (2) the eggs in their Figure 4B appear to measure about 100 microns in diameter, not the 240 microns stated in the text. Jim Lance (personal communication, 2005) has also noted planktotrophic development in D. gemela collected from San Diego. In a further twist, Jim has also observed direct development in a yellow-gill porostome from Bahia de Los Angeles in the Gulf of California. According to Gosliner et al. (1999), this latter form is also D. gemela. However, given the rarity of variable mode of development, or poecilogony, I suspect the form from Bahia de Los Angeles is actually a cryptic species. More work clearly remains on this taxon.
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Gosliner, T.M., M.C. Schaefer, and S.V. Millen. 1999. A new species of Doriopsilla (Nudibranchia: Dendrodorididae) from the Pacific coast of North America, including a comparison with Doriopsilla albopunctata (Cooper, 1863). The Veliger, 42:201-210.
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Goddard, J.H.R. 2005. Ametamorphic direct development in Dendrodoris behrensi (Nudibranchia: Dendrodorididae), with a review of developmental mode in the family. Proceedings of the California Academy of Sciences, 56: 201-211.
Best wishes,
Jeff
goddard@lifesci.ucsb.edu
Goddard, J.H.R., 2005 (Nov 23) Larval development in Doriopsilla gemela . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15331
Dear Jeff,
Thanks for these interesting observations. It would be interesting to know why some species lay flat egg masses like this, rather than the more 'normal' way with one edge attached to the substrate. It is apparently not restricted to one phylogenetic group as we know of many chromodorids that do it also [see Fact Sheet].
Best wishes,
Bill Rudman
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