Plakobranchus ocellatus

Plakobranchus ocellatus is a species of sea slug, a sacoglossan, a marine opisthobranch gastropod mollusk in the family Plakobranchidae.[1] It is found in shallow water in the Indo-Pacific region.

Plakobranchus ocellatus
Two Plakobranchus ocellatus seaslugs facing in opposite directions
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Gastropoda
(unranked):
clade Heterobranchia

informal group Opisthobranchia
clade Sacoglossa

clade Placobranchacea
Superfamily:
Plakobranchoidea
Family:
Plakobranchidae
Genus:
Plakobranchus
Species:
P. ocellatus
Binomial name
Plakobranchus ocellatus
(van Hasselt, 1824)
Synonyms[1]
  • Elysia ocellata Pease, 1860
  • Placobranchus gracilis Pease, 1871
  • Placobranchus guttatus Stimpson, 1855
  • Plakobranchus guttatus Stimpson, 1855
  • Placobranchus ianthobaptus Gould, 1852
  • Plakobranchus ianthobaptus Gould, 1852
  • Placobranchus ocellatus van Hasselt, 1824 (an incorrect subsequent spelling by Férussac (1824) in a translation of van Hasselt's work.)
  • Placobranchus variegatus Pease, 1871
  • Plakobranchus argus Bergh, 1872
  • Plakobranchus camiguinus Bergh, 1872
  • Plakobranchus chlorophacus Bergh, 1873
  • Plakobranchus laetus Bergh, 1872
  • Plakobranchus priapinus Bergh, 1872
  • Plakobranchus punctulatus Bergh, 1872

Distribution

This species occurs in the Indo-Pacific.[1] Recent work on the photosynthetic abilities of Plakobranchus reveals that P. ocellatus is actually a species complex consisting of at least four distinct clades.[2]

Description
Plakobranchus ocellatus, head end towards the left

The body is broad, truncate, and rather flattened, up to 4 cm (1.6 in) long.[1] The head is flat and squarish, the rhinophores being folded longitudinally. The mouth is at the front apex of the head and the eyes are very close together, being visible through the semi-transparent skin of the head. The dorsal surface of the sea slug has a number of longitudinal ridges, but when at rest, the parapodia are folded up over the midline of the body so that the dorsal surface is concealed from view. On the underside, the foot is broad and long, but is not clearly demarcated from the mantle.[3] The ground colour of this sea slug is usually pale green, beige, or cream with large ocelli (spots similar to eyespots) of cream, brown, pink, and purple in varying shades. The sole of the foot also has ocelli.[1]

Dorsal view of a freshly collected intact Plakobranchus ocellatus showing its head, rhinophores and parapodia.
Dorsal view of an anesthetized individual of Plakobranchus ocellatus with spread parapodia. Stomach and branched digestive glands are visible. The tissue region in the red square was dissected and used for DNA extraction in the study by Maeda T. et al. (2012).[4]

Habitat

These seaslugs live in sheltered, shallow water habitats with stones or gravel and silt.[1] They feed on a broad food spectrum, including members of the genera Halimeda, Caulerpa, Udotea, Acetabularia and further unidentified algae, with an emphasis on Halimeda macroloba.[2]

References

This article incorporates CC-BY-3.0 text from the reference.[1]

  1. Gofas, S. (2014). Plakobranchus ocellatus van Hasselt, 1824. Accessed through: World Register of Marine Species on 2014-11-08
  2. Christa G., Wescott L., Schäberle T.F., König G.M., Wägele H., (2013) What remains after 2 months of starvation? Analysis of sequestered algae in a photosynthetic slug, Plakobranchus ocellatus (Sacoglossa, Opisthobranchia), by barcoding. Planta. Feb;237(2):559-72. doi: 10.1007/s00425-012-1788-6. Epub 2012 Oct 30.
  3. Rao, K.V. (2015). "On two opisthobranchiate molluscs, Placobranchus ocellatus Hasselt and Discodoris boholiensis Bergh, from Indian waters not hitherto been recorded" (PDF). Journal of the Marine Biological Association of India. 3 (1&2): 253–255.
  4. Maeda T., Hirose E., Chikaraishi Y., Kawato M., Takishita K. et al. (2012). "Algivore or Phototroph? Plakobranchus ocellatus (Gastropoda) Continuously Acquires Kleptoplasts and Nutrition from Multiple Algal Species in Nature". PLoS ONE 7(7): e42024. doi:10.1371/journal.pone.0042024
  • Jensen K.R. (2007) Biogeography of the Sacoglossa (Mollusca, Opisthobranchia). Bonner Zoologische Beiträge 55:255–281
Wikimedia Commons has media related to Plakobranchus ocellatus.
  • Hirose E. (2005). "Digestive System of the Sacoglossan Plakobranchus ocellatus (Gastropoda: Opisthobranchia): Light- and Electron-Microscopic Observations with Remarks on Chloroplast Retention". Zoolog Sci. 22(8): 905–916.
  • Trench M. E, Trench R. K. & Muscatine L. (1970). "Utilization of photosynthetic products of symbiotic chloroplasts in mucus synthesis by Placobranchus ianthobapsus (Gould), Opisthobranchia, Sacoglossa". Comp Biochem Physiol. 37(1): 113–117.
  • Photos of Plakobranchus ocellatus on Sealife Collection
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