Elysia (gastropod) explained

Elysia is a genus of sea slugs, marine gastropod molluscs in the family Plakobranchidae. These animals are colorful sea slugs, and they can superficially resemble nudibranchs, but are not very closely related to them. Instead they are sacoglossans, commonly known as sap-sucking slugs.^[1]

Elysia sea slugs graze on algae and some species such as E. viridis and E. chlorotica hijack the chloroplasts for themselves. The chloroplasts end up lining the slug's digestive tract, enabling the slugs to survive solely by photosynthesis for several months at a time.This association is crucial for the development and maturing of the slug. Exactly how the slugs use the chloroplasts is unclear, as many of the proteins used by chloroplasts are encoded in the genome of the host cell. These proteins, numbering in the hundreds, are manufactured in the cell's nucleus, and then moved into the chloroplast, enabling it to survive.^[2] There has been a study regarding a member of the genus Elysia (E. chloritica), which states that there is horizontal gene transfer when the slugs ingest the algae. The study postulates that upon the ingestion of the algae, to keep the chloroplasts alive, E. chloritica steals genes via horizontal gene transfer to make proteins that maintain the chloroplasts.^[3] However, many^{[4] [5] [6]} other studies could not replicate the findings in the study and the claims remain disputed.Young specimens of E. atroviridis and E. marginata became known for their ability to regenerate the whole body from a severed head. This autotomy expels internal parasites.^[7]

This genus was previously sometimes considered to be in the family Stiligeridae, and was also previously placed in the family Elysiidae.

Species

The following species are recognised in the genus Elysia:

• Elysia abei
• Elysia amakusana
• Elysia amuravela
• Elysia annedupontae
• Elysia aowthai
• Elysia arena
• Elysia asbecki
• Elysia atroviridis
• Elysia australis
• Elysia babai
• Elysia bangtawaensis
• Elysia bella
• Elysia bengalensis
• Elysia bennettae
• Elysia brycei
• Elysia buonoi
• Elysia canguzua
• Elysia catulus
• Elysia chavelavargas
• Elysia chilkensis
• Elysia chlorotica
• Elysia christinae
• Elysia coodgeensis
• Elysia cornigera
• Elysia crispata
• Elysia deborahae
• Elysia degeneri
• Elysia delcarmen
• Elysia diomedea
• Elysia ellenae
• Elysia entredosaguas
• Elysia evelinae
• Elysia expansa
• Elysia faustula
• Elysia filicauda
• Elysia flava
• Elysia flavipunctata
• Elysia flavomacula
• Elysia frankenstein
• Elysia furvacauda
• Elysia grandifolia
• Elysia grandis
• Elysia hamatanii
• Elysia hedgpethi
• Elysia hendersoni
• Elysia hetta
• Elysia hirasei
• Elysia japonica
• Elysia jaramilloi
• Elysia jibacoaensis
• Elysia kushimotoensis
• Elysia leucolegnote
• Elysia lobata
• Elysia macnaei
• Elysia manriquei
• Elysia maoria
• Elysia marcusi
• Elysia margaritae
• Elysia marginata
• Elysia mercieri
• Elysia minima
• Elysia nealae
• Elysia nigrocapitata
• Elysia nigropunctata
• Elysia nisbeti
• Elysia obtusa
• Elysia oerstedii
• Elysia orientalis
• Elysia ornata
• Elysia papillosa
• Elysia patagonica
• Elysia patina
• Elysia pawliki
• Elysia pilosa
• Elysia pratensis
• Elysia punctata
• Elysia pusilla
• Elysia rubeni
• Elysia rufescens
• Elysia sanfermin
• Elysia serca
• Elysia siamensis
• Elysia singaporensis
• Elysia slimora
• Elysia stylifera
• Elysia subornata
• Elysia sugashimae
• Elysia thompsoni
• Elysia thysanopoda
• Elysia timida
• Elysia tokarensis
• Elysia tomentosa
• Elysia translucens
• Elysia trilobata
• Elysia trisinuata
• Elysia velutinus
• Elysia verrucosa
• Elysia viridis
• Elysia vreelandae
• Elysia yaeyamana
• Elysia zemi
• Elysia zuleicae

Species brought into synonymy:

• Elysia arena Carlson & Hoff, 1978: synonym of Pattyclaya arena (Carlson & Hoff, 1978)
• Elysia bedeckta MacFarland, 1966: synonym of Elysia hedgpethi Er. Marcus, 1961
• Elysia cauze scops Ev. Marcus & Er. Marcus, 1967: synonym of Elysia scops Ev. Marcus & Er. Marcus, 1967
• Elysia gracilis Risbec, 1928: synonym of Thuridilla gracilis (Risbec, 1928)
• Elysia halimedae Macnae, 1954: synonym of Elysia pusilla (Bergh, 1871)
• Elysia picta A. E. Verrill, 1901: synonym of Thuridilla picta (A. E. Verrill, 1901)
• Elysia pruvotfolae Er. Marcus, 1957: synonym of Elysia crispata Mørch, 1863
• Elysia schrammi Mörch, 1863: synonym of Elysia crispata Mørch, 1863
• Elysia splendida Grube, 1861: synonym of Thuridilla hopei (Vérany, 1853)
• Elysia thysanopoda Bergh, 1905: synonym of Thuridilla thysanopoda (Bergh, 1905)
• Elysia vataae Risbec, 1928: synonym of Thuridilla vataae (Risbec, 1928)
• Elysia verrilli Pruvot-Fol, 1946: synonym of Elysia crispata Mørch, 1863

Taxa inquirenda:

• Elysia fezi Vilella, 1968
• Elysia pruvotae Risbec, 1953

Further reading

• Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979
• Jensen K.R. (2007) Biogeography of the Sacoglossa (Mollusca, Opisthobranchia). Bonner Zoologische Beiträge 55:255–281
• Händeler . Katharina . Wagele . Heike . Preliminary study on molecular phylogeny of Saccoglossa and a compilation of their food organisms . Bonner Zoologische Beiträge . 2004 . 55 . 231–254 .
• http://www.catalogueoflife.org accessed 11 June 2009

External links

• Video of Elysia diomedea in Costa Rica

Notes and References

1. Bouchet, P.; Gofas, S. (2010). Elysia Risso, 1818. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137928 on 2010-12-14
2. Web site: Will we ever… photosynthesise like plants? . . https://web.archive.org/web/20190927211325/https://www.bbc.com/future/story/20120906-will-humans-ever-photosynthesise . 2019-09-27 . live .
3. Rumpho . Mary E. . Worful . Jared M. . Lee . Jungho . Kannan . Krishna . Tyler . Mary S. . Bhattacharya . Debashish . Moustafa . Ahmed . Manhart . James R. . Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica . Proceedings of the National Academy of Sciences . 18 November 2008 . 105 . 46 . 17867–17871 . 10.1073/pnas.0804968105 . free . 19004808 . 2584685 .
4. Chloroplast acquisition without gene transfer in photosynthetic sea slugs . Phys.org . National Institutes of Natural Sciences . 15 July 2021 .
5. Maeda . Taro . Takahashi . Shunichi . Yoshida . Takao . Shimamura . Shigeru . Takaki . Yoshihiro . Nagai . Yukiko . Toyoda . Atsushi . Suzuki . Yutaka . Arimoto . Asuka . Ishii . Hisaki . Satoh . Nori . Nishiyama . Tomoaki . Hasebe . Mitsuyasu . Maruyama . Tadashi . Minagawa . Jun . Obokata . Junichi . Shigenobu . Shuji . Chloroplast acquisition without the gene transfer in kleptoplastic sea slugs, Plakobranchus ocellatus . eLife . 27 April 2021 . 10 . 10.7554/eLife.60176 . free . 33902812 . 8079154 .
6. Bhattacharya . Debashish . Pelletreau . Karen N. . Price . Dana C. . Sarver . Kara E. . Rumpho . Mary E. . Genome Analysis of Elysia chlorotica Egg DNA Provides No Evidence for Horizontal Gene Transfer into the Germ Line of This Kleptoplastic Mollusc . Molecular Biology and Evolution . August 2013 . 30 . 8 . 1843–1852 . 10.1093/molbev/mst084 . 23645554 . 3708498 .
7. Web site: This sea slug can chop off its head and grow an entire new body, twice . Baker . Harry . 2021-03-08 . . 2021-03-09 .