Vaucheria litorea, an intertidal alga. The slug has an obligate relationship with the alga for both nutrients and physical development. (Green, et al., 2000; Pierce, et al., 1984; Rumpho, et al., 2011)is found in salt and tidal marshes, shallow creeks, and pools with depths of less than 0.5 m. The eastern sea slug is the most euryhaline osmoconformer known to date. The slug can survive salinity levels ranging from nearly fresh water (~24 mosm) to brackish salt water (~2422 mosm). is generally found close to its main food source,
V. litorea, and an adult stage. The stages of development are distinguishable based on the slug’s morphology and coloring. The slugs start as veliger larva, meaning they are equipped with a shell and ciliated vellum used for swimming and obtaining food. After metamorphosing to juveniles, the slugs are normally brown with ventrally-located spots of red pigmentation. only undergoes metamorphosis into the adult phase after exposure to and consumption of V. litorea, at which time its coloring and morphology also change. After the initial feeding, sequesters chloroplasts obtained from the plant into its specialized digestive tract. The presence of the chloroplasts turns the slug from brown to bright green. Most adults lose the red spots. The green color persists only as long as the slug has functional chloroplasts in its cells. When the chloroplasts are expelled, the slug loses its bright green color and reverts to a gray color. Adults normally range in size from 20 to 30 mm but specimens of up to 60 mm have been documented. The eastern emerald elsyia obtains its name from its adult structure. Elysid refers to the adult slug’s leaf-like shape which is caused by two large lateral parapodia on either side of its body. This morphology is beneficial as both camouflage and allowing the slug to be more efficient at photosynthesis. Other members of this family are distinguished by their parapodia in addition to bright coloring. (Colin, 1978; Humann, 1992; Pierce, et al., 1984; Rumpho, et al., 2001; Rumpho, et al., 2008; Rumpho, et al., 2011; Rumpho, et al., 2000)has two main life stages: a juvenile stage which is defined as the time before the slug begins feeding on
The blastula of a developingegg is holoblastic and spiral, meaning the eggs completely divide. At division, each plane is at an oblique angle to the animal's vegetal axis. Cells produce multiple tiers of cells with no clear center; this is referred to as a stereoblastula. Movements of cells occur by a process referred to as epiboly. Epiboly means that during development the ectoderm cells spread out to cover both the mesoderm and endoderm cell layers.
V. litorea. After 14 days of exposure to V. litorea and an additional two days of constant contact with this plant, metamorphoses into the adult leaf-shaped sea slug. The adult sea slug is bright green in color due to chloroplast cells that have been sequestered into the complex diverticula of the animal. Adults die shortly after they lay their string of eggs. Researcher Sidney Pierce suggests mass death is due to the expression of an unknown retro acting virus. (Hoffmeister and Martin, 2003; Pierce, et al., 1999; Rumpho, et al., 2011; Rumpho, et al., 2000; Schmitt, et al., 2007)has a veliger, juvenile, and adult stage of life. As a veliger larva, has a shell and ciliated vellum, a common feature among a sea slug's developmental cycle. During the larval stage these cilia help the larva to swim in its aquatic environment. Coloration in the larva is different due to the lack of retained chloroplasts in their diverticula. Diverticula are essentially openings along the digestive tract that result in small pocket in which an animal can store food, or in this case stolen chloroplasts. Veligers will metamorphose into juveniles in one to two days after exposure to
The details of how Elysia timida are dependent on the responses generated by the potential partner. These slugs will approach each other head to head and feel the other’s head with their own. Then, one (no way of telling how they decide which begins to move) will proceed downward moving their head down along the other slug’s body. If the partner accepts the invitation to mate the slugs will align head to tail. When the proper alignment is established, mating begins where both slugs insert their penes into the other’s genital area.initiates mating and the techniques used during mating are not well known. In a similar species, the mating behaviors of
Sexually reproducing hermaphrodites may act only as female or male. Sperm are less costly than eggs, so functioning as a male may be more desirable energetically. Many species of sea slugs within the clade Sacoglossa practice hypodermic insemination, in which the sperm of one slug is injected directly into the surface of another slug. They penetrate directly into the mate’s body in the general area of the others gonads and release the sperm directly inside their partner. (Rumpho, et al., 2011; Rumpho, et al., 2000; Schmitt, et al., 2007)
These slugs are simultaneous hermaphrodites, capable of internal self-fertilization, although this particular species more commonly outcrosses. Out-crossing is essential sexual reproduction with another individual. Eggs are laid in long mucous-laden strings, hatching approximately in a week. The eastern emerald elysia breeds once a year in the early spring. (Rumpho, et al., 2011; Rumpho, et al., 2000)
There are no documented incidents of parental care or investment in this species. Adults experience mass death both in natural and laboratory environments at approximately eleven months old. Pierce et al. (1984)suggest this is due to a viral expression, but little evidence exists. (Pierce, et al., 1984; Pierce, et al., 1999; Rumpho, et al., 2000; Schmitt, et al., 2007)
None documented (Schmitt, et al., 2007)
Little information is known on the techniques used by this species to communicate. Since the communication techniques of other sea slugs is variable, it is difficult to compare other species with (Brandly, 1984; Rumpho, et al., 2011; Schmitt, et al., 2007). The slug's eyes are not very developed.
V. litorea, and rarely feed upon Vaucheria compacta. The slug has an obligate relationship with its food source, requiring it for metamorphosis from the veliger to juvenile to the adult stage.is a kleptoplastic member of the clade Sacoglossa, which are sap sucking sea slugs. This species feeds exclusively on
As an adult, V. litorea cells. The contents of these cells pass through the slug’s highly specialized digestive tract. Over time the chloroplast cells are sequestered into the diverticula of the slug’s digestive system, causing it to turn bright green. After the digestive tract projects green coloration, is fully capable of photosynthesis for up to 10 months. Due to the slug’s photosynthetic nature, this species can often be found “sun bathing”, or laying with their parapodia extended to obtain maximum sunlight exposure. (Brandly, 1984; Mujer, et al., 1996; Pierce, et al., 1999; Pierce, et al., 1996; Rumpho, et al., 2001; Rumpho, et al., 2011; Rumpho, et al., 2000)obtains nutrients by consuming chloroplast cells from the alga. removes the chloroplast cells from the plant by projecting its radula, a scraping structure into the alga’s cell walls, and then sucking out the contents of
There are no known negative effects to humans from Elyisa chlorotica.
Elyisa chlorotica has no special status at this time. Populations are not in decline.
Members of this family are often brightly colored such as the Elysia picta which is known as the painted elysia. The main body of the painted elysia is green but laterally there are vivid bands of orange, blue, and neon green. The brown lined elysia, Elysia subornata has a bright green body and parapodia but also has a thin brown line along the very edge of its’ wing-like structures. (Colin, 1978; Humann, 1992)
Chelsea Blanchet (author), Radford University, Karen Powers (editor), Radford University, Kiersten Newtoff (editor), Radford University, Melissa Whistleman (editor), Radford University, Renee Mulcrone (editor), Special Projects.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
marshes are wetland areas often dominated by grasses and reeds.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
movements of a hard surface that are produced by animals as signals to others
Brandly, B. 1984. Aspects of the ecology and physiology of Elysia cf. furvacuda (Mollusca: Sacoglossa). Bulletin of Marine Science, 34/2: 207-219.
Colin, P. 1978. Marine Invertebrates And Plants of the Living Reef. Neptune city, /Nj: T.F.H Publications.
Green, B., W. Li, J. Manhart, T. Fox, E. Summer, R. Kennedy, S. Pierce, M. Rumpho. 2000. Mollusc-algal chloroplast endosymbiosis. Photosynthesis, thylakoid protein maintenance, and chloroplast gene expression continue for many months in the absence of the algal nucleus. Plant Physiology, 124/1: 331-342.
Hoagland, K., R. Robertson. 1988. An assessment of poecilogony in marine invertebrates: phenomenon or fantasy?. The Biological Bulletin, 174/2: 109-125.
Hoffmeister, M., W. Martin. 2003. Interspecific evolution: microbial symbiosis, endosymbiosis and gene transfer. Environmental Microbiology, 5/8: 641-649.
Humann, P. 1992. Reef Creature Identification. Jacksonville, Fl: New World Publications.
Händeler, K., Y. Grzymbowski, P. Krug, H. Wägele. 2009. Functional chloroplasts in metazoan cells - a unique evolutionary strategy in animal life. Frontiers in Zoology, 6/28: 1-18.
Kim, E., J. Archibald. 2010. Plastid evolution: Gene transfer and the maintenance of ‘stolen’ organelles. BMC Biology, 8/73: 1-3.
Mujer, C., D. Andrews, J. Manhart, S. Pierce, M. Rumpho. 1996. Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica. Cell Biology, 93/22: 12333-12338.
Pierce, S. 1982. Invertebrate cell volume control mechanisms: a coordinated use of intracellular amino acids and inorganic ions as osmotic solute. The Biological Bulletin, 1603: 405-419.
Pierce, S., R. Biron, M. Rumpho. 1996. Endosymbiotic chloroplasts in molluscan cells contain proteins synthesized after platid capture. The Journal of Experimental Biology, 199/10: 2323-2330.
Pierce, S., S. Edwards, P. Mazzocchi, L. Klingler, M. Warren. 1984. Proline betaine: A unique osmolyte in an extremely euryhaline osmoconformer. The Biological Bulletin, 167/2: 495-500.
Pierce, S., T. Maugel, M. Rumpho, J. Hanten, W. Mondy. 1999. Annual viral expression in a sea slug population: Life cycle control and symbiotic chloroplast maintenance. The Biological Bulletin, 197/6: 1-6.
Rumpho, M., K. Pelletreau, A. Moustafa, D. Bhattacharya. 2011. The making of a photosynthetic animal. The Journal of Experimental Biology, 214/2: 303-311.
Rumpho, M., E. Summer, B. Green, T. Fox, J. Manhart. 2001. Mollusc/algal chloroplast symbiosis: how can isolated chloroplasts continue to function for months in the cytosol of a sea slug in the absence of an algal nucleus?. Zoology, 104: 303-312.
Rumpho, M., E. Summer, J. Manhart. 2000. Solar-powered sea slugs. Mollusc/algal chloroplast symbiosis. Plant Physiology, 123/1: 29-38.
Rumpho, M., J. Worful, J. Lee, M. Tyler, D. Bhattacharya, A. Moustafa, J. Manhart. 2008. Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica. PNAS, 105/46: 17867-17871.
Schmitt, V., N. Anthes, N. Michiels. 2007. Mating behaviour in the sea slug Elysia timida (Opisthobranchia, Sacoglossa): hypodermic injection, sperm transfer and balanced reciprocity. Frontiers in Zoology, 4/17: 1-9.