Question
Are there any animals that can photosynthesise? If so how?
Answer
Yes, some animals can photosynthesize, primarily through symbiotic relationships with photosynthetic organisms or by retaining photosynthetic organelles. Here are the main ways animals achieve photosynthesis:
Kleptoplasty in Sea Slugs
Sea Slugs (Sacoglossan Molluscs): Certain sea slugs, like Elysia chlorotica, can photosynthesize by retaining chloroplasts from the algae they consume. This process, known as kleptoplasty, allows the sea slugs to use the chloroplasts for photosynthesis, providing them with energy and fixed carbon for their lifespan (Rumpho et al. 303 – 311; Maeda et al.; Rola et al.).
Symbiotic Relationships
Cnidarians and Sponges: Many cnidarians (e.g., corals, sea anemones) and sponges form symbiotic relationships with algae or cyanobacteria. These symbionts live within the animal’s tissues and perform photosynthesis, sharing the photosynthetically-fixed carbon with their host (Venn et al.
1069-80
; Clavijo et al.; Hinde).
Amphibians: Some amphibian eggs have been found to engage in photosymbiosis, although this is less common and not as well understood as in invertebrates (Yang et al.).
Mechanisms and Challenges
Symbiotic Mechanisms: The symbiotic algae release low molecular weight compounds like maltose and glycerol to the host, which are used as energy sources. However, these relationships can be sensitive to environmental changes, which may lead to bleaching and breakdown of the symbiosis (Venn et al.
1069-80
; Hinde).
Genomic Adaptations: The evolution of photosymbiosis in animals likely involves genomic adaptations that facilitate the recognition and maintenance of symbionts. This area remains under-researched, particularly outside of cnidarians (Clavijo et al.; Rola et al.).
Conclusion
In summary, while animals do not inherently photosynthesize like plants, some have developed unique adaptations to harness photosynthesis through symbiotic relationships or by retaining chloroplasts from their diet. These adaptations highlight the diverse strategies animals have evolved to exploit photosynthetic processes.
References
M. Rumpho et al. “The making of a photosynthetic animal.” Journal of Experimental Biology, 214 (2011): 303 – 311. https://doi.org/10.1242/jeb.046540
A. Venn et al. “Photosynthetic symbioses in animals..” Journal of experimental botany, 59 5 (2008): 1069-80. https://doi.org/10.1093/jxb/erm328
Jenny Melo Clavijo et al. “Polymorphic adaptations in metazoans to establish and maintain photosymbioses.” Biological Reviews, 93 (2018). https://doi.org/10.1111/brv.12430
T. Maeda et al. “Chloroplast acquisition without the gene transfer in kleptoplastic sea slugs, Plakobranchus ocellatus.” eLife, 10 (2020). https://doi.org/10.1101/2020.06.16.155838
R. Hinde et al. “Animals with Photosynthetic Symbionts.” Annals of the New York Academy of Sciences, 503 (1987). https://doi.org/10.1111/j.1749-6632.1987.tb40620.x
Marcellina Rola et al. “Cladobranchia (Gastropoda, Nudibranchia) as a Promising Model to Understand the Molecular Evolution of Photosymbiosis in Animals.” **, 8 (2022). https://doi.org/10.3389/fmars.2021.745644
H. Yang et al. “Organismal and cellular interactions in vertebrate-alga symbioses..” Biochemical Society transactions (2022). https://doi.org/10.1042/BST20210153
[1] Rumpho, M. E., Pelletreau, K. N., Moustafa, A. and Bhattacharya, D. (2011) The making of a photosynthetic animal. Journal of Experimental Biology, 214(2): 303–31
[2] Marilyn J. Roossinck, (2011) The good viruses: viral mutualistic symbioses. Nature Reviews Microbiology 9, 99-108
[3] Mondy, W. L. and Pierce, S. K., (2003) Apoptotic-like morphology is associated with annual synchronized death in kleptoplastic sea slugs (Elysia chlorotica). Invertebrate Biology 122(2): 126-137.
