''Elysia serca'', the seagrass elysia or Caribbean seagrass elysia, is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary ...

, a marine gastropod mollusc in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Plakobranchidae. Although this sea slug resembles a

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to mat ...

, it is not a nudibranch; it belongs to the clade,

Sacoglossa Sacoglossa, commonly known as the sacoglossans or the "solar-powered sea slugs", are a superorder of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia. Sacoglossans live by ingesting the cellula ...

, the "sap-sucking" sea slugs. It was first described by Marcus in 1955 from specimens found in Brazil.

Taxonomy

''Elysia clena'' is a species first described from

Curaçao Curaçao ( ; ; pap, Kòrsou, ), officially the Country of Curaçao ( nl, Land Curaçao; pap, Pais Kòrsou), is a Lesser Antilles island country in the southern Caribbean Sea and the Dutch Caribbean region, about north of the Venezuela coas ...

by Marcus in 1970. Jensen (1982) determined that it was a junior synonym of ''Elysia serca'', first described by Marcus from Brazil in 1955. This was on the basis of the morphology of the radular teeth, the dorsal venation and biological observations. ''Elysia serca'' also bears great similarities to '' Elysia catulus'' (Gould, 1870), a species with a more northerly distribution, and Jensen (1983) considers that ''E. serca'' may be a subspecies or

ecotype In evolutionary ecology, an ecotype,Greek: ''οίκος'' = home and ''τύπος'' = type, coined by Göte Turesson in 1922 sometimes called ecospecies, describes a genetically distinct geographic variety, population, or race within a specie ...

of ''E. catulus''. Features in common between the two include the anatomy of the mouth, the shape of the radular teeth and the paths taken by the dorsal veins.

Description

''Elysia serca'' is a small, slender sea slug with a maximum length of . The

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...

are less well developed than is the case in many other '' Elysia'' species and ''Elysia serca'' has a relatively large head. The characteristic radular teeth have the cusps bent at right angles to their bases. The base colour is some shade of brown or olive with many small patches of white and three larger white patches, two on the parapodia and one on the back near the heart.''Elysia serca; Marcus, 1955
The Sea Slug Forum. Retrieved 2012-01-27.
Smithsonian Marine Station at Fort Pierce. Retrieved-2012-01-28.

Distribution and habitat

''Elysia serca'' is found in shallow waters in the western Atlantic from Florida south to Brazil. It was originally described from the southern end of its range, where it was found on

brown algae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate an ...

and the green alga ''

Ulva Ulva (; gd, Ulbha) is a small island in the Inner Hebrides of Scotland, off the west coast of Mull. It is separated from Mull by a narrow strait, and connected to the neighbouring island of Gometra by a bridge. Much of the island is formed f ...

'', on which it was presumably feeding. In Florida however it feeds on

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families ( Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the ...

es including '' Halophila engelmannii'', '' Halodule wrightii'' and '' Thalassia'' at depths of up to a few metres. ''Elysia catulus'' on the other hand, feeds on the seagrass ''

Zostera ''Zostera'' is a small genus of widely distributed seagrasses, commonly called marine eelgrass, or simply seagrass or eelgrass, and also known as seaweed by some fishermen and recreational boaters including yachtsmen. The genus ''Zostera'' con ...

'' and is found on the North American coast between

South Carolina )'' Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no) , anthem = "Carolina";" South Carolina On My Mind" , Former = Province of South Carolina , seat = Columbia , LargestCity = Charleston , LargestMetro = G ...

and

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native En ...

.''Elysia catulus'' (Gould, 1870)
The Sea Slug Forum. Retrieved 2012-01-28.

Biology

In Florida, there is a great variation in the size of populations of ''Elysia serca'' at different times of year. This is likely to be because the life span is less than a year and recruitment, and the establishment of new populations, comes as a result of

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cr ...

ic larvae arriving from elsewhere and settling. Feeding is done by puncturing the plant cells with the radular tooth and sucking out the liquid contents. ''Elysia serca'' shows a preference for, and grows faster on, ''Halophila engelmannii''. This may be because the plant has large

epidermal The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...

cells which are easy to exploit or because of the absence of

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner ...

s, a chemical defence against

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthp ...

s used by some seagrasses.

References

{{Taxonbar, from=Q3197430 Plakobranchidae Gastropods described in 1955