The spotted sea hare (''Aplysia punctata'') is a

species In biology, a species is the basic unit of 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 the appropriate s ...

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 t ...

in the family

Aplysiidae Aplysiidae is the only family in the superfamily Aplysioidea, within the clade Anaspidea. These animals are commonly called sea hares because, unlike most sea slugs, they are often quite large, and when they are underwater, their rounded body sh ...

, the sea hares.Gofas, S. (2011). Aplysia punctata. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138758 on 2012-03-31 It reaches a length of up to and is found in the northeast Atlantic, ranging from

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

and

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

to the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

Life cycle

Spawning occurs in the springtime beginning in May as water temperature warms and continues until around October with species tending to only live for approximately one year. ''Aplysia punctata'' are

simultaneous hermaphrodite Simultaneous hermaphroditism is one of the two types of hermaphroditism, the other type being sequential hermaphroditism. In this form of hermaphroditism an individual has sex organs of both sexes and can produce both gamete types even in the sam ...

s with their individual sexual role being determined by either mass or egg-laying specialization. However, they do not self-fertilize and engage in mating behavior that can involve multiple individuals. During warmer months, behavior is dominated by reproduction and feeding, with little time spent crawling or remaining sedentary. Embryos develop from laid eggs and continue to a larval stage, becoming temporary members of the plankton. Larva rapidly transform into juveniles with sexual maturity typically occurring within three and four months from birth. ''A. punctata'' are benthic gastropods found in both littoral and sublittoral habitats with a large range spanning the northeast Atlantic and the Mediterranean sea. They are known to colonize both shallow, intertidal waters and also deeper zones within their range.

Feeding

''Aplysia punctata'' are grazing organisms which prefer to reside and feed on algal seaweed beds. Using their

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

, ''A. punctata'' tear up seaweeds in order to consume them and are found to eat up to one-third of their body weight per day of algae. Individuals of ''A. punctata'' found in the intertidal area are recorded to be larger than those in deep waters due to a comparatively larger abundance of food. However, individuals with smaller diets are thought to have lower initial mortality rates and live longer than those with unlimited diets suggesting that caloric restriction is advantageous. Feeding and sexual reproduction both take place upon algal beds which provide a source of food and protection for ''A. punctata''. Their coloration is usually determined from the pigments in the seaweed they feed upon which in turn also provides them with camouflage. Mediterranean species of ''A. punctata'' feed primarily on red algae of the genus ''

Laurencia ''Laurencia'' is a genus of red algae that grow in temperate and tropical shore areas, in littoral to sublittoral habitats, at depths up to . Description ''Laurencia'' species have a thallus that is erect or decumbent with distichous, whorled ...

'' which provide them with metabolites known to produce antifungals, antivirals, and

cytotoxins Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

for self defense.

Sensory organs

The rhinophores for ''Aplysia punctata'' are located both on their head and posterior tentacle. Their namesake as "sea hares" arises from the morphology of the rhinophores which look similar to rabbit ears. The rhinophore is the olfactory organ for the species and it is used to detect pheromones. Auditory and visual information is limited in ''A. punctata'' and so the function of the rhinophore is critical. This chemosensatory action assists in the localization of food and in sexual behavior. Amino acids are observed to be an olfactory stimulant to elicit feeding responses. Serotoninergic fibers are also found in the rhinophore nerves which are believed to have a physiological role in olfactory responses to amino acid presence. The

glomeruli ''Glomerulus'' () is a common term used in anatomy to describe globular structures of entwined vessels, fibers, or neurons. ''Glomerulus'' is the diminutive of the Latin ''glomus'', meaning "ball of yarn". ''Glomerulus'' may refer to: * the filter ...

and the

ganglion A ganglion is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympatheti ...

are segments of the rhinophore which represent different processing stages of sensory information; the processing of odor information takes place in the ganglion. ''Aplysia punctata'' also have large neurons which make them a model species in the study of the cellular basis of learning and memory. They are known to be among the largest in nature which assists in studies that attempt to explain how neural circuits control behavior. Their increased size is attributed to being

polyploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

somatic cell A somatic cell (from Ancient Greek σῶμα ''sôma'', meaning "body"), or vegetal cell, is any biological cell forming the body of a multicellular organism other than a gamete, germ cell, gametocyte or undifferentiated stem cell. Such cells compo ...

s. It is observed to be an advantageous adaptation that allows for enhanced speed of electrical signals resulting in faster behavioral response times. The central nervous system and neurons are located on the ganglionic surface and possess unique coloration depending on location.

Shell calcification

''Aplysia punctata's'' shell is located internally to protect their heart and other organs from environmental conditions like wave action. However, it is comparatively thinner and smaller than ones possessed by other gastropods. Their shell is observed to measure up to 6 cm in larger specimens. Accretionary growth bands may be observed on larger specimens, akin to those seen on the shells of

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

and other

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

. The main element composing ''A. punctata's'' shell is aragonite that is deposited within a protein matrix. Aragonite is a form of calcium carbonate which notably is susceptible to dissolution in lower sea water pH. As a species of mollusk, ''Aplysia punctata'' performs marine

calcification Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature Mat ...

in building and maintaining their shell material. This species of sea hare is unique for its shell resilience in acidified ocean environments. Most marine species with shells (mollusks, echinoderms, corals, coccolithophores, foraminiferans, calcifying algae, etc.) experience increased dissolution and increasing energetic costs of maintaining and growing these structures in this basic environment. However, living in the middle to lower intertidal zone and shallow waters, ''A. punctata'' naturally faces fluctuations in pH and has been observed to have no decrease in calcification of new shell material when exposed to acidic environments similar to those of having increased dissolved carbon dioxide. Although, they do undergo increased metabolic rate in low pH environments which is attributed to the maintenance of calcium carbonate and aragonite structures in waters depleted of these materials.

References

This article incorporates CC-BY-2.0 text from reference. * Backeljau, T. (1986). ''Lijst van de recente mariene mollusken van België''

ist of the recent marine molluscs of Belgium Ist or IST may refer to: Information Science and Technology * Bachelor's or Master's degree in Information Science and Technology * Graduate School / Faculty of Information Science and Technology, Hokkaido University, Japan * Graduate School ...

Koninklijk Belgisch Instituut voor Natuurwetenschappen: Brussels, Belgium. 106 pp * Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification''. Collection Patrimoines Naturels, 50: pp. 180–213 * Muller, Y. (2004). F''aune et flore du littoral du Nord, du Pas-de-Calais et de la Belgique: inventaire. oastal fauna and flora of the Nord, Pas-de-Calais and Belgium: inventory'. Commission Régionale de Biologie Région Nord Pas-de-Calais: France. 307 pp * {{Taxonbar, from=Q520464 punctata Gastropods described in 1803 Taxa named by Georges Cuvier