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.
Communication Channels: tactile ; chemical
Perception Channels: visual ; tactile ; chemical
Elysia crispata does not have any special conservation status, but like other species of the genus, it has not been evaluated.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
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.
Development - Life Cycle: metamorphosis
Elysia crispata does not negatively affect humans.
Elysia crispata is not of any major economic importance to humans, but it is sold in the aquarium trade.
Positive Impacts: pet trade
There is not much yet known about the ecosystem roles of Elysia crispata.
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.
Plant Foods: algae
Primary Diet: herbivore (Algivore)
Elysia crispata is native to the Caribbean Sea and is found from Florida Keys to Bermuda.
Biogeographic Regions: neotropical (Native )
Elysia crispata prefers tropical reefs and thrives in environments abundant with algae, mainly at depths from 0.5 to 12 m.
Range depth: 0.5 to 12 m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: reef ; coastal
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.
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.
Range length: 5 to 10 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Some sea slugs are toxic to deter predators, but there is no available literature about any predators for Elysia crispata.
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.
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.
Average number of offspring: 1020.
Key Reproductive Features: simultaneous hermaphrodite; sexual ; fertilization (Internal ); oviparous
No evidence of post-fertilization investment parental investment for Elysia crispata has been noted.
Parental Investment: no parental involvement
Elysia crispata, common name the lettuce sea slug or lettuce slug, is a large and colorful species of sea slug, a marine gastropod mollusk.[1]
The lettuce slug resembles a nudibranch, but it is not closely related to that clade of gastropods; it is classified as a sacoglossan.
This species is called the lettuce slug because it is often green in color, and it always has a very frilly edge to its parapodia. This makes the slug resemble the curly kinds of lettuce, such as the lollo rosso variety. The maximum length of this species is about 5 cm and 3 cm in width.[2]
The lettuce slug is extremely variable in color: it can also be blue, or very pale with red lines or yellow lines.
This species lives in the tropical parts of the western Atlantic, and the Caribbean faunal zone. They are found in more coastal and tropical reef areas where the water is shallow and clear.[3]
E. crispata can be either heterotrophic or autotrophic throughout their lifespan.[4] As juveniles, food is consumed and digested quickly, with little chloroplast retention. Upon reaching maturity, kleptoplasty becomes an important energy source.[4] The primary food source of E. crispata is relatively unknown, although some individuals have been known to consume a diversity of algal species such as Vaucheria litorea, Caulerpa verticillata, Caulerpa racemosa, Halimeda discoidea, Halimeda incrassate, Halimeda monile, and Penicillus capitatus; C. verticillata being suitable for a limited amount of time.[4][5][6] This diversity in food sources is a different characteristic compared to other Sacoglossan’s who are specialized for one species of algae, and gives E. crispata a survival advantage when food is depleted or sparse.[6] Chloroplasts within their parapodia (fleshy dorsal protrusions) continue to produce energy products through carbon fixation throughout their life and have been found to function efficiently for a little over a month.[5]
Also known as chloroplast symbiosis, kleptoplasty is the energy-providing mechanism that gives the Sacoglossan’s the nickname, “solar-powered sea slugs”, and E. crispata the name, “lettuce sea slug.” As algal food is being digested, the chloroplasts are absorbed into the cells lining the digestive tract and up into their parapodia.[7] How many chloroplasts the slug sequesters and the length of retention depends on the individual species of slug. Chloroplast retention in E. crispata tends to last around 40 days.[5] Given the variation in their diet, chloroplasts from different algal species have been found to be taken up into the same cells, functioning normally alongside the other.[6]
E. crispata is closely related to E. chlorotica, both having a long-term chloroplast retention ability, where other species within the same genus tend to have more short-term retention.[5] This ability makes it possible to withstand long periods of time without food. In the absence of food, E. crispata will invest energy trying to find food rather than slowing down and conserving energy.[5][7] Although it hasn’t been exclusively studied for this organism, one possibility of the mechanism behind long-term retention is due to the amount of extracellular components which prolong chloroplast activity, depending on the species of algae eaten.[5] As E. crispata continues to consume food, the chloroplasts ingested will continuously replace older chloroplasts while food is available.[7] Their long-term retention is an evolutionary adaption which allows a greater chance of survival during drastic environmental changes.[7]
Very little is known of the mating behaviors of E. crispata. Typically the egg mass is laid on flat, upright algae, and embryo development takes about 15 days.[8] Eggs are very small, between 106–113 micrometres, and eggs vary in average size by location.[8]
Newly hatched E. crispata demonstrate a dispersal dimorphism, not to be confused with poecilogony.[8] Babies can either undergo intracapsular metamorphosis, or post-hatching metamorphosis, giving E. crispata variation in their dispersal strategy.[8] This allows some clutches to remain stationary to that habitat, or allowing them to swim to a new habitat before metamorphosing.[8] Some species of Sacoglossan such as Elysia tuca, invest extra energy to create extra-cellular yolk which is weaved into their egg mass, providing a greater abundance of nutrients for larval growth, which in turn produces larger progeny.[8] E. crispata, however, does not produce extra-cellular yolk, which affects the size of the eggs.[8]
Elysia crispata, common name the lettuce sea slug or lettuce slug, is a large and colorful species of sea slug, a marine gastropod mollusk.
The lettuce slug resembles a nudibranch, but it is not closely related to that clade of gastropods; it is classified as a sacoglossan.
