Elysia viridis
MOLLUSCA
Sacoglossa
✨🔵🐌 This adorable sea slug is the sacoglossan Elysia viridis. This is a Gastropod mollusca, just like land snails and slugs. You can identify this common species of the intertidal zone with its beautiful blue-green iridescent spots shining in the sun!
☀️🌱☀️ But this little guy also hides a superpower! Often called, “solar-powered” sea slugs, they can retain the chloroplasts from the seaweed that they eat in their own cells! It means that they are able to do like plants, and use the sun as source of energy! Isn’t it insane?
🥷🥗😋 This specific process is called kleptoplasty, litteraly meaning (chloro)plast thief… and is particularly important for the survival of the animal in periods of food scarcity! Don’t you wish you were able to do the same?!
🧬🔁🌱 Some open questions remain on the molecular mechanisms that allow them to maintain the chloroplasts functional within their own cells. Indeed, these are a very complex machineries specific to plants, and animal cells are not supposed to use them! It’s like using a very complex machine without the appropriate tools and instruction manual… To explain this, some researchers have proposed that seaweed genes (= the instruction manual) were transferred to the slug genome by horizontal transfer (understand “non-genealogically”), but this assumption remains debated in other species.
👁️👁️The 2 small eye spots are not very developed and probably provide a quite basic vision. On the contrary, rhinophores – the two rolled antenna at the front of the head – are the main sensory organs of sea slugs.
👃💧Coming from the greek [rhino-] = nose, rhinophores can sense chemicals diluted in the sea water, like an aquatic sense of smell. They likely help the animals to locate food sources, predators, and partners of the same species.
⚧️🌀 Indeed, even if this sacoglossan species is a simultaneous hermaphrodite, the animals need to find a partner and act both as a male and female during cross-fertilisation. When they are done, the eggs are laid in a nice spirale on an algae, I hope to find one soon to show you!
🔰🫀 The two fleshy protrusionson each side of the body are called parapodia. On the inner side, we can see a network of dorsal vessels distributing the hemolymph – the equivalent of blood – from the heart to the entire body. This little guy has kept his parapods closed the whole time, but they sometimes extend to maximize the surface area, catch the sun’s rays and photosynthesize!
🔪🤕 Fun fact, a closely related species of sacoglossan (E.marginata) can perform an extreme form of autotomy. They can shed their entire body from the neck if they are attacked! The head is then sufficient to initiate a whole body regeneration and completely restore a functional body in no more than 18 days! Authors proposed that this amazing ability is facilitated by the endosymbiodic chloroplasts that provides energy independantly of food ingestion… I really wonder if Elysia viridis have the same surviving skills 🤔
Sources
- MarLIN
- Doris
- https://opistobranquis.info/en/guia/sacoglossa/plakobranchoidea/elysia-viridis/
- Baumgartner, Finn A., Henrik Pavia, and Gunilla B. Toth. “Acquired Phototrophy through Retention of Functional Chloroplasts Increases Growth Efficiency of the Sea Slug Elysia Viridis.” PLOS ONE 10, no. 4 (April 1, 2015): e0120874.https://doi.org/10.1371/journal.pone.0120874.
- Cartaxana, Paulo, Erik Trampe, Michael Kühl, and Sónia Cruz. “Kleptoplast Photosynthesis Is Nutritionally Relevant in the Sea Slug Elysia Viridis.” Scientific Reports 7 (August 10, 2017): 7714.https://doi.org/10.1038/s41598-017-08002-0.
- “Food Shaped Photosynthesis: Photophysiology … | Open Research Europe.” Accessed May 5, 2024.https://open-research-europe.ec.europa.eu/articles/3-107.
- Händeler, Katharina, Yvonne P Grzymbowski, Patrick J Krug, and Heike Wägele. “Functional Chloroplasts in Metazoan Cells – a Unique Evolutionary Strategy in Animal Life.” Frontiers in Zoology 6 (December 1, 2009): 28.https://doi.org/10.1186/1742-9994-6-28.
- Mitoh, Sayaka, and Yoichi Yusa. “Extreme Autotomy and Whole-Body Regeneration in Photosynthetic Sea Slugs.” Current Biology 31, no. 5 (March 8, 2021): R233–34.https://doi.org/10.1016/j.cub.2021.01.014.
- Neusser, Timea P, Felix Hanke, Gerhard Haszprunar, and Katharina M Jörger. “‘Dorsal Vessels’? 3D-Reconstruction and Ultrastructure of the Renopericardial System of Elysia Viridis (Montagu, 1804) (Gastropoda: Sacoglossa), with a Discussion of Function and Homology.” Journal of Molluscan Studies 85, no. 1 (February 1, 2019): 79–91.https://doi.org/10.1093/mollus/eyy049.
- Rumpho, Mary E., Jared M. Worful, Jungho Lee, Krishna Kannan, Mary S. Tyler, Debashish Bhattacharya, Ahmed Moustafa, and James R. Manhart. “Horizontal Gene Transfer of the Algal Nuclear Gene PsbO to the Photosynthetic Sea Slug Elysia Chlorotica.” Proceedings of the National Academy of Sciences 105, no. 46 (November 18, 2008): 17867–71.https://doi.org/10.1073/pnas.0804968105.
- Wägele, Heike, Oliver Deusch, Katharina Händeler, Rainer Martin, Valerie Schmitt, Gregor Christa, Britta Pinzger, et al. “Transcriptomic Evidence That Longevity of Acquired Plastids in the Photosynthetic Slugs Elysia Timida and Plakobranchus Ocellatus Does Not Entail Lateral Transfer of Algal Nuclear Genes.” Molecular Biology and Evolution 28, no. 1 (January 2011): 699–706.https://doi.org/10.1093/molbev/msq239.