Elysia crispata

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Geographic Range

Elysia crispata is native to the Caribbean Sea and is found from Florida Keys to Bermuda. (Pierce, et al., 2006)

Habitat

Elysia crispata prefers tropical reefs and thrives in environments abundant with algae, mainly at depths from 0.5 to 12 m. (Pierce, et al., 2006; Snyderman and Wiseman, 1996)

  • Range depth
    0.5 to 12 m
    1.64 to 39.37 ft

Physical Description

Elysia crispata is typically green with white spots, however, indiviuduals with other colors can be found. Some have a rainbow of blues and yellows decorating their frilled bodies. The elongated visceral mass of Elysia crispata lies dorsally on top of the foot of the animal. The parapodia, dorsal to the visceral mass, form the distinctly ruffled, lettuce-like appearance on the dorsal surface of the body. This characteristic is responsible for the common name of the species, the lettuce sea slug. Although Elysia crispata is a mollusk, it does not have a mantle cavity, gills, or an osphradium, but does have a foot and radula.

The hermaphroditic organ, the ovatestes, is located throughout the parapodia. The hermaphroditic duct allows eggs and sperm to leave the ovatestes. Ventral to the parapodia, the hermaphroditic duct splits into tubes leading to distinct male and female reproductive parts. The oviduct is the female portion of the hermaphroditic duct, leading to the female gland and the female pore. The seminal receptacle is attached to the female gland. The male potion of the hermaphroditic duct is the sperm duct, which leads to the male atrium, which contains the penis. The seminal vesicle is located under the atrium. The atrium has a small pore called the male pore. During sexual reproduction, the penis comes through the male pore and into its mate's female pore. Sperm are ejected from the seminal vesicle of the male organs into the seminal vesicle of the mate. The sperm then internally fertilizes the eggs in the female gland. (Fox, 2001)

  • Range length
    5 to 10 cm
    1.97 to 3.94 in

Development

Elysia crispata has an egg, larval, juvenile and adult stage. Egg diameter is about 120 μm, and the eggs hatch in about 15 days. Larval size is approximately 290 μm. The larvae are non-feeding veligers that metamorphosize into juvenile slugs after approximately five days. Juveniles are about 530 μm long. Captive juvenile lettuce sea slugs are sessile underneath a light source, not moving until they have matured. Once the individuals become adults, they will acquire symbiotic plastids from aquatic algae, such as Halimeda incrassata and Penicillus capitatus. (Pierce, et al., 2006)

Reproduction

Elysia crispata is hermaphroditic, reproducing sexually via cross fertilization, and fertilization occurs internally. During sexual reproduction, the penis comes through the male pore and into its mate's female pore. Sperm are ejected from the seminal vesicle of the male organs into the seminal vesicle of the mate. The sperm then internally fertilizes the eggs in the female gland. (Clark, 1975; Fox, 2001)

Lettuce sea slugs have large clutch sizes compared to other Elysia species; for other species clutch size ranges from 30 to 500. Specific mating behaviors for E. crispata are unknown, but a similar species, Elysia catulus, produces eggs in June and July, and die by late July. (Clark, 1975; Krug, 2009)

  • Average number of offspring
    1020

No evidence of post-fertilization investment parental investment for Elysia crispata has been noted.

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

The lifespan of Elysia crispata has not been studied, but a similar species, Elysia catulus, has a lifespan just under a year. Larvae of this species arrive at the end of the summer months, grow to maturity and produce eggs in June and July, and die by late July. (Clark, 1975)

Behavior

Elysia crispata is a mobile creature, only sessile as juveniles to gain energy from a light source. This species is hermaphroditic and will meet with another individual to reproduce. There is no available information as to their social behavior, territory size, and methods of communication. (Fox, 2001; Pierce, et al., 2006)

Home Range

There is no available information on individual territory size or territorial habits. (Pierce, et al., 2006)

Communication and Perception

In general, gastopods use slime secretions to communicate and tentacles to receive messages. The role of rhinopores is usually for chemoreception as well, but in nudibranchs, this role may vary with genera. Chemoreception is the main receptive channel for feeding, avoiding predators and toxins and to synchronize mating. Visual reception in gastropods is still being investigated. (Audesirk and Audesirk, 1983)

Food Habits

Elysia crispata is a herbivorous suctorial feeder. This species will eat the cell sap of algae but do not digest all of it. The lettuce sea slug will use its radula to pierce algal cells and suck their contents out by using its pharynx. Some of the chloroplasts that Elysia crispata eat are not digested. Instead, they are funneled through specific passages in the digestive tract and stored in the parapodia. These chloroplasts, which can live inside the E. crispata for up to four months, undergo photosynthesis while living in the parapodia.

The importance of Sacoglossan kleptoplasty (the use of chloroplasts) has been analyzed in close relatives of Elysia crispata. In an experiment on Elysia timida, specimens kept in the dark for 28 days were found to have lower survival rates (up to -30%) than those kept in the light. This leads us to believe that kleptoplasts provide these mollusks with extra energy to compensate for a shortage of food. (Curtis, et al., 2005; Fox, 2001; Snyderman and Wiseman, 1996)

  • Plant Foods
  • algae

Predation

Some sea slugs are toxic to deter predators, but there is no available literature about any predators for Elysia crispata.

Ecosystem Roles

There is not much yet known about the ecosystem roles of Elysia crispata.

Economic Importance for Humans: Positive

Elysia crispata is not of any major economic importance to humans, but it is sold in the aquarium trade.

Economic Importance for Humans: Negative

Elysia crispata does not negatively affect humans.

Conservation Status

Elysia crispata does not have any special conservation status, but like other species of the genus, it has not been evaluated.

Contributors

Valentina Noto (author), Rutgers University, Kerry Queenan (author), Rutgers University, David V. Howe (editor), Rutgers University, Renee Mulcrone (editor), Special Projects.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

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.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

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.

internal fertilization

fertilization takes place within the female's body

metamorphosis

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.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Audesirk, T., G. Audesirk. 1983. Behavior of Gastropod Molluscs. Pp. 1-94 in A Willows, ed. Volume 8. Neurobiology and Behavior, Part I., Vol. 8. Orlando, Florida: Academic Press, Inc..

Capman, B. 2002. "Lettuce sea slug - Elysia crispata (Tridachia crispata)" (On-line). Accessed June 06, 2011 at http://www.augsburg.edu/home/biology/photoofmonth/lettuceseaslug.html.

Casalduero, F., C. Maniain. 2008. The role of kleptoplasts in the survival rates of Elysia timida (Risso, 1818): (Sacoglossa: Opisthobranchia) during periods of food shortage. Journal of Experimental Marine Biology and Ecology, 357: 181-187.

Clark, K. 1975. Nudibranch life cycles in the northwest Atlantic and their relationship to the ecology of fouling communities. Helgolander wiss, 27: 28-69.

Curtis, N., S. Massey, J. Schwartz, T. Maugel, S. Pierce. 2005. The intracellular, functional chloroplasts in adult sea slugs (Elysia crispata) come from several algal species, and are also different from those in juvenile slugs. Microscopy and Microanalysis, 11: 1194-1195.

Earle, S. 2009. Gulf of Mexico Origin, Waters, and Biota: Biodiversity. USA: Texas A&M University Press. Accessed June 06, 2011 at http://books.google.com/books?id=CphA8hiwaFIC&printsec=frontcover#v=onepage&q&f=false.

Fox, R. 2001. "Tridachia crispata" (On-line). Invertebrate Anatomy OnLine. Accessed June 06, 2011 at http://webs.lander.edu/rsfox/invertebrates/tridachia.html.

Krug, P. 2009. Not my “type”: larval dispersal dimorphisms and bet-hedging in opisthobranch life histories. Biology Bulletin, 216: 355-372.

Pierce, S., N. Curtis, S. Massey, A. Bass, C. Finney. 2006. A morphological and molecular comparison between Elysia crispata and a new species of kleptoplastic sacoglossan sea slug (Gastropoda: Opisthobranchia) from the Florida Keys, USA. Molluscan Research, 26 (1): 4.

Rudman, W. 2006. "Elysia crispata (Morch, 1863).." (On-line). Sea Slug Forum. Accessed June 10, 2011 at http://www.seaslugforum.net/factsheet/elyscris.

Snyderman, M., C. Wiseman. 1996. Guide to Marine Life: Caribbean, Bahamas, Florida. Locust Valley, New York: Aqua Quest Publications.

Trench, R., R. Greene, B. Bystrom. 1969. Chloroplasts as functional organelles in animal tissues. The Journal of Cell Biology, 42: 404-417.