''Aplysia'' () is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of medium-sized to extremely large

sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

s, specifically

sea hare The order Aplysiida, commonly known as sea hares ('' Aplysia'' species and related genera), are medium-sized to very large opisthobranch gastropod molluscs with a soft internal shell made of protein. These are marine gastropod molluscs in t ...

s, which are a kind of marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

. These

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

herbivorous creatures can become rather large compared with most other mollusks. They graze in

tidal Tidal is the adjectival form of tide. Tidal may also refer to: * ''Tidal'' (album), a 1996 album by Fiona Apple * Tidal (king), a king involved in the Battle of the Vale of Siddim * TidalCycles, a live coding environment for music * Tidal (servic ...

and

subtidal The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminate ...

zones of tropical waters, mostly in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

Ocean (23 species); but they can also be found in the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

(12 species), with a few species occurring in the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

. ''Aplysia'' species, when threatened, frequently release clouds of ink, it is believed in order to blind the attacker (though they are in fact considered edible by relatively few species). Following the lead of Eric R. Kandel, the genus has been studied as a

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

by neurobiologists, because its gill and siphon withdrawal reflex, as studied in ''Aplysia californica'', is mediated by

electrical synapse An electrical synapse, or gap junction, is a mechanical and electrically conductive synapse, a functional junction between two neighboring neurons. The synapse is formed at a narrow gap between the pre- and postsynaptic neurons known as a gap junc ...

s, which allow several

neuron A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...

s to fire synchronously. This quick neural response is necessary for a speedy reaction to danger by the animal. Aplysia has only about 20,000

neurons A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...

, making it a favorite subject for investigation by neuroscientists. Also, the 'tongue' on the underside is controlled by only two neurons, which allowed complete mapping of the innervation network to be carried out.

Long-term memory

s that mediate several forms of long-term

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...

in ''Aplysia'', the

DNA repair DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is cons ...

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

poly ADP ribose polymerase Poly (ADP-ribose) polymerase (PARP) is a family of proteins involved in a number of cellular processes such as DNA repair, genomic stability, and programmed cell death. Members of PARP family The PARP family comprises 17 members (10 putative ...

1 (PARP-1) is activated. In virtually all

eukaryotic The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

cells tested, the addition of polyADP-ribosyl groups to proteins (poly

ADP-ribosylation ADP-ribosylation is the addition of one or more ADP-ribose moieties to a protein. It is a reversible post-translational modification that is involved in many cellular processes, including cell signaling, DNA repair, gene regulation and apoptosis ...

) occurs as a response to DNA damage. Thus the finding of activation of PARP-1 during learning and its requirement for long-term memory was surprising. Cohen-Aromon et al. suggested that fast and transient decondensation of

chromatin Chromatin is a complex of DNA and protein found in eukaryote, eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important r ...

structure by polyADP-ribosylation enables the

transcription Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including: Genetics * Transcription (biology), the copying of DNA into RNA, often th ...

needed to form long-term memory without strand-breaks in DNA. Subsequent to these findings in ''Aplysia'', further research was done with mice and it was found that polyADP-ribosylation is also required for long-term memory formation in

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s. In 2018, scientists from the University of California, Los Angeles, have shown that the behavioral modifications characteristic of a form of nonassociative long-term memory in ''Aplysia'' can be transferred by RNA.

Operant conditioning

Operant conditioning Operant conditioning, also called instrumental conditioning, is a learning process in which voluntary behaviors are modified by association with the addition (or removal) of reward or aversive stimuli. The frequency or duration of the behavior ma ...

is considered a form of associative

learning Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, Attitude (psychology), attitudes, and preferences. The ability to learn is possessed by humans, non-human animals, and ...

. Because operant conditioning involves intricate interaction between an action and a stimulus (in this case food) it is closely associated with the acquisition of compulsive behavior. The ''Aplysia'' species serve as an ideal model system for the physical studying of food-reward learning, due to "the neuronal components of parts of its ganglionic nervous system that are responsible for the generation of feeding movements." As a result, ''Aplysia'' has been used in associative learning studies to derive certain aspects of feeding and operant conditioning in the context of compulsive behavior. In ''Aplysia'', the primary reflex studied by scientists while studying operant conditioning is the gill and siphon withdrawal reflex. The gill and siphon withdrawal reflex allows the ''Aplysia'' to pull back its siphon and gill for protection. The links between the synapses during the gill and siphon withdrawal reflex are directly correlated with many behavioral traits in the ''Aplysia'' such as its habits, reflexes, and conditioning. Scientists have studied the conditioning of the ''Aplysia'' to identify correlations with conditioning in mammals, mainly regarding behavioral responses such as addiction. Through experiments on the conditioning of the ''Aplysia'', links have been discovered with the synaptic plasticity for reward functions involved in the trait of addiction within mammals. Synaptic plasticity is the idea that the synapses will become stronger or weaker depending on how much those specific synapses are used. Conditioning of these synapses can lead them to become stronger or weaker by causing the neurons to fire or not fire when influenced by a stimulus. The conditioning of behavioral traits is based on the idea of a reward function. A reward function is when a stimulus is conditioned to fire according to a certain stimulus. The neurons will adapt to that stimulus, and fire those neurons more easily, even if the stimulus has a negative effect on the subject (in this case the Aplysia). In mammals, the reward function is mainly controlled by ventral tegmental area (VTA) dopamine neurons. During conditioning (in mammals), the VTA dopamine neurons have an increased effect on the stimuli being conditioned, and a decreased effect on the stimuli not being conditioned. This induces the synapses to form an expectation for reward for the stimuli being conditioned. The properties of the synapses displayed in the tests on conditioning involving the ''Aplysia'' (which has dopamine neurons but not a ventral tegmental area) are proposed to be directly comparable to behavioral responses such as addiction in mammals.

Reproduction

''Aplysia'' are simultaneous hermaphrodites, meaning each adult individual sea hare possesses both male and female reproductive structures that may be mature at the same time. ''Aplysia'' have the ability to store and digest allosperm (sperm from a partner) and often mate with multiple partners. A potent

sex pheromone Sex pheromones are pheromones released by an organism to attract an individual of the same species, encourage them to mate with them, or perform some other function closely related with sexual reproduction. Sex pheromones specifically focus on ind ...

, the water-borne protein attractin, is employed in promoting and maintaining mating in ''Aplysia''. Attractin interacts with three other Aplysia protein pheromones (enticin,

temptin Temptin is a protein that acts as a water-borne pheromone in the marine gastropod mollusk ''Aplysia californica''. It is an abundant protein that is synthesized in the albumen gland, and is released in the egg cords during oviposition, along with ot ...

or seductin) in a binary fashion to stimulate mate attraction. Studies of multiple matings in the

California sea hare The California sea hare (''Aplysia californica'') is a species of sea slug in the sea hare family, Aplysiidae.Rosenberg, G.; Bouchet, P. (2011). Aplysia californica J. G. Cooper, 1863. Accessed through: World Register of Marine Species at http:// ...

, ''Aplysia californica,'' have provided insights on how conflicts between the sexes are resolved.

Self-defense

''Aplysia'' species was once thought to use ink to escape from predators, much like the

octopus An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like oth ...

. Instead, recent research has made it clear that these sea slugs are able to produce and secrete multiple compounds within their ink, including the chemodeterrant

Aplysioviolin Aplysioviolin is a purple-colored molecule secreted by sea hares of the genera ''Aplysia'' and ''Dolabella (gastropod), Dolabella'' to deter predators. Aplysioviolin is a chemodeterrent, serving to dispel predators on Olfaction, olfactory and Tas ...

and toxic substances such as

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

for self-defense. The ability of the ''Aplysia'' species to hold toxins within their bodies without poisoning themselves is a result of the unique way that the toxin is stored within the slug. Different molecules essential to the creation of the toxin are accumulated in separate parts of the body of the slug, rendering them benign, as only the mixing of all the molecules can result in a toxic chemical cloud. When the sea hare feels threatened it immediately begins the process of defending itself by mixing the distinct molecules in an additional part of the body used specifically for that purpose. At which point, enzymes within the sea slug begin the process of making the substance toxic, and the mixture is ejected out at the predator in self-defense.

Species

Species within the genus ''Aplysia'' are as follows. This list follows the studies of Medina et al. who established a phylogenetic hypothesis for the genus ''Aplysia'' through study of the partial

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

l DNA (mtDNA) sequence data of

ribosomal genes The ribosomal DNA (rDNA) consists of a group of ribosomal RNA encoding genes and related regulatory elements, and is widespread in similar configuration in all domains of life. The ribosomal DNA encodes the non-coding ribosomal RNA, integral struc ...

(rDNA).

* ''

Aplysia argus ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Rüppell & Leuckart, 1830 * '' Aplysia atromarginata'' Bergh, 1905 * ''

Aplysia brasiliana ''Aplysia fasciata'', common name the "mottled sea hare", or the "sooty sea hare", is an Atlantic species of sea hare or sea slug, a marine (ocean), marine opisthobranch gastropod mollusk in the family Aplysiidae. Distribution This sea hare occu ...

'' Rang, 1828 * ''

Aplysia californica The California sea hare (''Aplysia californica'') is a species of sea slug in the sea hare family, Aplysiidae.Rosenberg, G.; Bouchet, P. (2011). Aplysia californica J. G. Cooper, 1863. Accessed through: World Register of Marine Species at http:/ ...

'' (J.G. Cooper, 1863) California sea hare ** Distribution: Northeast Pacific * ''

Aplysia cedrocensis ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Bartsch & Rehder, 1939) ** Distribution: Northeast Pacific * ''

Aplysia cervina ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine (ocean), marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other ...

'' (Dall & Simpson, 1901) ** Distribution: West Atlantic * ''

Aplysia cornigera ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Sowerby, 1869 ** Distribution: Indian Ocean, West Pacific * ''

Aplysia cronullae ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Eales, 1960: synonym of '' Aplysia extraordinaria'' (Allan, 1932) (uncertain synonym) ** Distribution: Southwest Pacific * '' Aplysia dactylomela'' (Rang, 1828) spotted sea hare ** Distribution:

Cosmopolitan Cosmopolitan may refer to: Internationalism * World citizen, one who eschews traditional geopolitical divisions derived from national citizenship * Cosmopolitanism, the idea that all of humanity belongs to a single moral community * Cosmopolitan ...

; tropical and temperate seas. ** Color: from pale gray to green to dark brown. ** Description: large black rings on the mantle; good swimmer * '' Aplysia denisoni'' Smith, 1884: synonym of '' Aplysia extraordinaria'' (Allan, 1932) (possible senior synonym) ** Distribution: Indian Ocean, West Pacific * ''

Aplysia depilans ''Aplysia depilans'', the depilatory sea hare, is a species of sea hare or sea slug, a marine opisthobranch gastropod mollusk in the family Aplysiidae. Its name has led to a folk etymology that its consumption caused hair loss. Distribution This ...

'' (

Gmelin Gmelin may refer to: * Karl Christian Gmelin, Carl Christian Gmelin (1762–1837), German botanist, author of ''Flora Badensis, Alsatica et confinium regionum cis- et transrhenania'' (1806) * Charles Gmelin (1872–1950), British Olympic athlete * ...

, 1791) ** Distribution: Northeast Atlantic, Mediterranean. ** Description: thin, yellow inner shell * ''

Aplysia dura ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Eales, 1960 ** Distribution: Southeast Atlantic, Southwest Pacific * '' Aplysia elongata'' (Pease, 1860) * ''

Aplysia euchlora ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Adams in M.E.Gray, 1850: represented as ''Aplysia'' (''Phycophila'') ''euchlora'' (Gray, 1850) (alternate representation) ** Distribution: Northwest Pacific * '' Aplysia extraordinaria'' (Allan, 1932) (possibly = ''Aplysia gigantea'') ** Distribution: Western Australia, New Zealand. ** Length: more than 40 cm * '' Aplysia fasciata'' (Poiret, 1798) ( ''Aplysia brasiliana'' Rang, 1828 is a junior synonym). ** Distribution: East Atlantic, Mediterranean, West Africa, Red Sea ** Length: 40 cm ** Color: dark brown to black. ** Description: sometimes has a red border to the parapodia and oral tentacles * '' Aplysia ghanimii'' Golestani, Crocetta, Padula, Camacho, Langeneck, Poursanidis, Pola, Yokeş, Cervera, Jung, Gosliner, Araya, Hooker, Schrödl & Valdés, 2019 * ''

Aplysia gigantea ''Aplysia gigantea'' is a species of sea slug, a shell-less Marine (ocean), marine gastropod mollusk in the family Aplysiidae. The species was first described in the ''Journal of the Malacological Society of Australia'' in 1869. A. gigantea is al ...

'' Sowerby, 1869 ** Distribution: Indian Ocean, West Pacific * ''

Aplysia hooveri ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Golestani, Crocetta, Padula, Camacho, Langeneck, Poursanidis, Pola, Yokeş, Cervera, Jung, Gosliner, Araya, Hooker, Schrödl & Valdés, 2019 * ''

Aplysia inca ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' d'Orbigny, 1837 ** Distribution: Southeast Pacific * ''

Aplysia japonica ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' G. B. Sowerby II, 1869 * ''

Aplysia juanina ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Bergh, 1898) * ''

Aplysia juliana ''Aplysia juliana'', the walking sea hare, is a species of sea hare, a marine gastropod in the family Aplysiidae. Distribution Distribution of this species is cosmopolitan, circumtropical in all warm seas. Description This sea hare has no purp ...

'' ( Quoy &

Gaimard Joseph Paul Gaimard (31 January 1793 – 10 December 1858) was a French naval surgeon and naturalist. Biography Gaimard was born at Saint-Zacharie on January 31, 1793. He studied medicine at the naval medical school in Toulon, subsequent ...

, 1832) Walking sea hare ** Distribution: cosmopolitan, circumtropical in all warm seas ** Color: various, from uniform to pale brown ** Description: no purple gland, therefore no ink secretions; posterior end of the foot can act as a sucker * '' Aplysia keraudreni'' Rang, 1828 ** Distribution: South Pacific ** Length: 25 cm ** Color: dark brown * ''

Aplysia kurodai ''Aplysia kurodai'' is a species of gastropods belonging to 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 sl ...

'' (Baba, 1937) ** Distribution: NW Pacific ** Length: 30 cm ** Color: dark brown to purplish black, dotted with white spots * ''

Aplysia lineolata ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' A. Adams & Reeve, 1850: synonym of '' Aplysia oculifera'' A. Adams & Reeve, 1850 * ''

Aplysia maculata ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine (ocean), marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other ...

'' Rang, 1828 ** Distribution : Western Indian Ocean * '' Aplysia morio'' ( A. E. Verrill, 1901) Atlantic black sea hare, sooty sea hare ** Distribution: Northwest Atlantic ** Length: 40 cm ** Color: black to deep brown; no spots * ''

Aplysia nigra ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' d'Orbigny, 1837 ** Distribution: Southwest Atlantic, South Pacific * ''

Aplysia nigra brunnea ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Hutton, 1875 ** Distribution:

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

** Length: 10 cm ** Color: dark brown * ''

Aplysia nigrocincta ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' von Martens, 1880 * '' Aplysia oculifera'' (Adams & Reeve, 1850) spotted sea hare ** Distribution: Indian Ocean; West Pacific; common along the north, east and south coast of

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

** Length: 15 cm ** Description: greenish brown, with small brown to black spots with white centres ** Habitat: shallow bays and estuaries ** Behaviour: hides by day; emerges at night to feed on seaweed * ''

Aplysia parva ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Pruvot-Fol, 1953 * ''

Aplysia parvula The dwarf sea hare or pygmy sea hare, ''Aplysia parvula'', is a species of sea hare, a marine (ocean), marine gastropod mollusc in the family Aplysiidae.Rosenberg, G.; Gofas, S. (2012). Aplysia parvula Mørch, 1863. Accessed through: World Regist ...

'' (Guilding in Moerch, 1863) pygmy sea hare,

dwarf sea hare The dwarf sea hare or pygmy sea hare, ''Aplysia parvula'', is a species of sea hare, a marine gastropod mollusc in the family Aplysiidae.Rosenberg, G.; Gofas, S. (2012). Aplysia parvula Mørch, 1863. Accessed through: World Register of Marine Sp ...

** Distribution: worldwide in warm to temperate seas ** Length: 6 cm ** Color: brown to green spots * '' Aplysia peasei'' (Tryon, 1895) (''

taxon inquirendum In biological classification, a ''species inquirenda'' is a species of doubtful identity requiring further investigation. The use of the term in English-language biological literature dates back to at least the early nineteenth century. The ter ...

'') * ''

Aplysia perviridis ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Pilsbry, 1895) * ''

Aplysia pilsbryi ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Letson, 1898) * '' Aplysia pulmonica'' Gould, 1852 * ''

Aplysia punctata The spotted sea hare (''Aplysia punctata'') is a species of sea slug in the family Aplysiidae, the sea hares.Gofas, S. (2011). Aplysia punctata. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxd ...

'' (

Cuvier Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...

, 1803) ** Distribution: NE Atlantic ** Length: 20 cm ** Color: very variable * ''

Aplysia rehderi ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Eales, 1960 ** Distribution: Northeast Pacific * ''

Aplysia reticulata ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Eales, 1960 ** Distribution: Southwest Pacific * ''

Aplysia reticulopoda ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Beeman, 1960) net-foot sea hare ** Distribution: Northeast Pacific * '' Aplysia robertsi'' Pilsbry, 1895 ** Distribution: Northeast Pacific * ''

Aplysia rudmani ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Bebbington, 1974 ** Distribution: Indian Ocean * ''

Aplysia sagamiana ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Baba, 1949) ** Distribution: East Australia, Japan; Northwest Pacific *

Aplysia sowerbyi ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

Pilsbry, 1895 ** Distribution: Southwest Pacific * ''

Aplysia sydneyensis ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' (Sowerby, 1869) ** Distribution: Australia ** Length: 15 cm ** Description: not clearly defined * ''

Aplysia tanzanensis ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Bebbington, 1974 ** Distribution: Indian Ocean * ''

Aplysia vaccaria ''Aplysia vaccaria'', also known as the black sea hare and California black sea hare, is a species of extremely large sea slug, a marine, opisthobranch, gastropod mollusk in the family Aplysiidae.Bouchet, P. (2011). Aplysia vaccaria Winkler, 195 ...

'' (Winkler, 1955) California black sea hare (possibly ?= ''Aplysia cedrocensis'') ** Distribution: Pacific Coast of California ** Length: very big – up to 75 cm ** Color: black ** Description: no purple ink; huge internal shell * ''Aplysia venosa'' Hutton, 1875 (''

'') * ''

Aplysia vistosa ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk. These benthic herbivorous creatures can become rather large compared with most other mollusks. They ...

'' Pruvot-Fol, 1953 ;Species brought into synonymy: * ''Aplysia aequorea'' Heilprin, 1888: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia albopunctata'' ''Deshayes, 1853'': synonym of ''Aplysia punctata'' (Cuvier, 1803) * ''Aplysia angasi'' G.B. Sowerby II, 1869: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia annulifera'' Thiele, 1930: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia ascifera'' Rang, 1828: synonym of ''

Dolabrifera dolabrifera ''Dolabrifera dolabrifera'' is a species of sea hare, a marine gastropod mollusc in the family Aplysiidae, the sea hares. ''Dolabrifera dolabrifera,'' otherwise known as a ''Warty Seacat.'' The animal goes by many names, including the common se ...

'' (Rang, 1828) * ''Aplysia benedicti'' Eliot, 1899: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia bourailli'' Risbec, 1951: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia brasiliana'' (Rang, 1828) mottled sea hare, sooty sea hare (junior synonym of ''Aplysia fasciata''; different geographical populations of the same species): synonym of '' Aplysia fasciata'' Poiret, 1789 * ''Aplysia cirrhifera'' Quoy & Gaimard, 1832: synonym of '' Barnardaclesia cirrhifera'' (Quoy & Gaimard, 1832) * ''Aplysia concava'' Sowerby, 1869: synonym of ''Aplysia parvula'' Mørch, 1863 * ''Aplysia depressa'' Cantraine, 1835: synonym of ''

Phyllaplysia depressa ''Phyllaplysia'' is a genus of sea slugs, specifically sea hares, marine (ocean), marine gastropod mollusks in the family (biology), family Aplysiidae, the sea hares. Some authors place this genus in a separate family, Dolabriferidae. Species S ...

'' (Cantraine, 1835) * ''Aplysia dolabrifera'' Rang, 1828: synonym of ''

'' (Rang, 1828) * ''Aplysia donca'' (Ev. Marcus & Er. Marcus, 1960): synonym of '' Aplysia morio'' (A. E. Verrill, 1901) * ''Aplysia eusiphonata'' Bergh, 1908: synonym of ''Aplysia maculata'' Rang, 1828 * ''Aplysia fimbriata'' Adams & Reeve, 1850: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia gargantua'' Bergh, 1908: synonym of ''Aplysia maculata'' Rang, 1828 * ''Aplysia geographica'' (Adams & Reeve, 1850): synonym of ''

Syphonota geographica ''Syphonota geographica'', or the geographic sea hare, is a species of sea slug or sea hare, a marine opisthobranch gastropod mollusk in the family Aplysiidae, the sea hares. This is the only species within this genus, in other words, ''Syphon ...

'' (A. Adams & Reeve, 1850) * ''Aplysia gilchristi'' Bergh, 1908: synonym of ''Aplysia maculata'' Rang, 1828 * ''Aplysia gracilis'' Eales, 1960: synonym of ''Aplysia fasciata'' Poiret, 1789 * ''Aplysia griffithsiana'' Leach, 1852 synonym of ''Aplysia punctata'' (Cuvier, 1803) * ''Aplysia guttata'' Sars M., 1840 synonym of Aplysia punctata (Cuvier, 1803) * ''Aplysia hamiltoni'' Kirk, 1882: synonym of ''Aplysia juliana'' Quoy & Gaimard, 1832 * ''Aplysia hybrida'' Sowerby, 1806: synonym of ''Aplysia punctata'' (Cuvier, 1803) * ''Aplysia longicauda'' Quoy & Gaimard, 1825: synonym of ''

Stylocheilus longicauda ''Stylocheilus longicauda'' is a species of gastropods belonging to the family Aplysiidae. The species is found in Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlan ...

'' (Quoy & Gaimard, 1825) * ''Aplysia megaptera'' Verrill, 1900: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia nettiae'' Winkler, 1959: synonym of ''Aplysia californica'' J. G. Cooper, 1863 * ''Aplysia norfolkensis'' Sowerby, 1869: synonym of ''Aplysia parvula'' Mørch, 1863 * ''Aplysia oahouensis'' Souleyet, 1852: synonym of ''

'' (Rang, 1828) * ''Aplysia ocellata'' d'Orbigny, 1839: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia odorata'' Risbec, 1928: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia operta'' Burne, 1906: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia petalifera'' Rang, 1828: synonym of ''

Petalifera petalifera ''Petalifera'' is a genus of sea slugs or sea hares, marine (ocean), marine gastropod mollusks belonging to the family (biology), family Aplysiidae, the sea hares. Some authors place this genus in a separate family Dolabriferidae. A new study, p ...

'' (Rang, 1828) * ''Aplysia poikilia'' Bergh, 1908: synonym of ''Aplysia maculata'' Rang, 1828 * ''Aplysia protea'' Rang, 1828: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia pulmonica'' Gould, 1852: synonym of ''

'' Rüppell & Leuckart, 1830 * ''Aplysia radiata'' Ehrenberg, 1831: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia rosea'' Rathke, 1799: synonym of ''Aplysia punctata'' (Cuvier, 1803) * ''Aplysia schrammi'' Deshayes, 1857: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia scutellata'' Ehrenberg, 1831: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia sibogae'' Bergh, 1905: synonym of ''Aplysia juliana'' Quoy & Gaimard, 1832 * ''Aplysia striata'' Quoy & Gaimard, 1832: synonym of ''

'' (Quoy & Gaimard, 1825) * ''Aplysia tigrina'' Rang, 1828: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia tigrinella'' Gray, 1850: synonym of ''Aplysia maculata'' Rang, 1828 * ''Aplysia tigrinella'' Gray, 1850: synonym of ''

'' Rang, 1828 * ''Aplysia velifer'' Bergh, 1905: synonym of ''Aplysia dactylomela'' Rang, 1828 * ''Aplysia willcoxi'' (Hellprin, 1886): synonym of '' Aplysia fasciata'' Poiret, 1789 * ''Aplysia winneba'' Eales, 1957: synonym of '' Aplysia fasciata'' Poiret, 1789

References

* Kandel Eric R., Schwartz, J.H., Jessell, T.M. 2000. ''

Principles of Neural Science ''Principles of Neural Science'' is a neuroscience textbook edited by Columbia University professors Eric R. Kandel, James H. Schwartz, and Thomas M. Jessell. First published in 1981 by McGraw-Hill, the original edition was 468 pages, and has ...

'', 4th ed., p. 180. McGraw-Hill, New York. * * Howson, C.M.; Picton, B.E. (Ed.) (1997). ''The species directory of the marine fauna and flora of the British Isles and surrounding seas''. Ulster Museum Publication, 276. The Ulster Museum: Belfast, UK. . vi, 508 (+ cd-rom) 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

External links

* * Photos of ''Aplysia''
MondoMarino.net
* {{Authority control Animal models Animal models in neuroscience Taxa named by Carl Linnaeus Gastropod genera