Hind gill slugs

Hind gill slugs
	Various hind gills (Opisthobranchia)
Systematics
Trunk :	Molluscs (mollusca)
Class :	Snails (gastropoda)
Subclass :	Orthogastropoda
Subclass :	Apogastropoda
Superordinate :	Heterobranchia
Order :	Hind gill slugs
Scientific name
	Opisthobranchia
	H. Milne Edwards , 1848

The hind- gill snails (Opisthobranchia, Greek οπισθοβράγχια - ὄπισθεν "behind", βράγχιον "gill") are the group of snails that have gills behind the heart and a lateral mantle cavity. Hinterkiemer are hermaphrodites and have hermaphroditic glands . Many have a receded shell or no shell at all, and instead of comb gills, dorsal feather gills or skin breathing . Shellless species developed deterrent, camouflage, or distraction techniques for self-defense. Most of them live near the seabed. However, there are also permanent swimmers and a few freshwater species. Hind gills feed on carrion and plant remains, graze on seaweed, colonies of small animals, sponges, cnidarians, or hunt prey. Species with indirectly used photosynthesis by undigested symbiotic small algae or absorbed chloroplasts are a specialty . Their relatively short life consists of two to three developmental phases. The larval phase ( Veliger larvae ) that is not always present is often spent as plankton . The taxon has been known since the 19th century and is also an integral part of the modern systematics by Ponder & Lindberg (1997) and Bouchet & Rocroi (2005).

Some features

The dominant feature of the hind- gill snails (Opisthobranchia) are gills lying on the right behind the heart and a lateral mantle cavity .

This location is a product of snail ontogenesis. This begins with a coat ( pallium ). At one end (head end) are u. a. the throat, eyes, and nerve ganglia. Downstream of this are u. a. the internal organs. The digestive tract from the throat to the anus and paired nerve cords run through the body from the head to the end. Due to the formation of the strong foot muscle on the underside of the head towards the end, the softer downstream part with the internal organs is pushed upwards and rotates to the right ( torsion ). The internal order of the organs in the jacket sack (viscera) remains unchanged. Viewed from the outside, however, the position of the organs, measured as the distance from the head, changes compared to the state before the torsion. In the anterior gills, a 180 ° torsion resulted in the gills being closer to the head end than the heart. However, the hind gills are followed by a detorsion phase in which the changes in position of the first torsion are partially reversed. After that, the heart is closer to the head again than the gills and the jacket pouch at an angle to the right behind the heart.

The feather gills of a magnificent snail ( Chromodoris coi )

Cerata : internal branching

Breathing . In many species, breathing takes place through the comb gills ( ctenidia ) located in the sac cave . Comb gills are well-perfused skin protuberances with many hair cells (ciliary cells) that carry out gas exchange when water flows through them. In the nudibranchs, however, the mantle cavity and gills have receded. Instead, skin processes ( cerata ) form on the back (dorsal) , which are traversed by fine capillary vessels connected to the cardiovascular system. The Cerata branch out very strongly internally or externally. In the latter case the species produce different characteristic shapes: rosettes, isolated bundles, stalked and sessile tufts, and the like. Similar to the inner gills, the strong branching increases the surface of the skin and improves the gas exchange with the water. One speaks of feather gills, especially when there are strong external branches .

In various snails (e.g. Aeolidiidae ) the cerata are traversed by papillaries connected to the digestive tract and take over, among other things. a. Defense tasks, see protective mechanisms.

Sea hare ( Aplysia dactylomela ) genus of large snails

The hind gill snails vary in size from a few millimeters to tens of centimeters. Many snails are about 2–6 cm in length. Tiny snails are found in various families of the subordination of cephalaspidea (Cephalaspidea), for example. B. Noalda (0.9 mm), Retusa sp. (1.5mm). Similarly, very small snails such as B. Acteon lacunatus , Acteon parallelus , Acteon semicingulatus (3 mm), Enotepteron rosewateri (4 mm), Siphopteron quadrispinosum (5 mm). Smaller snails are z. B. Hermaea dendritis (11 mm), Coryphella gracilis (15 mm). Medium-sized snails are e.g. B. Green velvet snail (often 2 cm), Glaucus atlanticus (4 cm), Bulla striata (6 cm). Larger types of snail are the shaggy tree snail (10 cm) and Tritona hombergi (12 cm). The genus sea hare ( Aplysia ) is one of the largest snails . Alypsia fasciata 40 cm long was found in Europe . Of Aplysia vaccaria even 75 cm long specimens are known.

Hind gills have the following life phases : the maturation phase in the egg cell in clutches or spawning cords, which is concluded with hatching, the larval phase , which is not present in all species , often spent as plankton, which ends with metamorphosis (transformation of form), and the phase as the actual snail with reproduction. The life expectancy of the hind gills is not very high. For many species it is around a year. Some snails die soon after they lay eggs. Some exemplary life expectancies follow: Eubranchus pallidus - 8 months, Archidoris tuberculata - 12 months, Aeolidia papillosa - 16 months, Dendronotus frondosus - 24 months.

Habitats

Because of their gills, hindgill snails are aquatic inhabitants. Among them there are some freshwater species (within the Acochlidiacea ). However, the dominant number of species are marine life.

The maritime habitats can be described according to different criteria:

far from the coast by depth
coastal areas based on tides (permanent flood zone, lower and upper tidal zone, tide pools)
according to soil type (sandy soils, sediment soils, mud and silt soils, hard soils, rocky soils)
after vegetation (algae, kelp forests, seagrass meadows, coral banks, colonies of bog animals, sponges, cnidarians)
by climate zone (arctic - tropical seas)

The group of hindgill snails comprises a very wide range of species. It is therefore not surprising that they occur in all seas and oceans and that they have opened up a wide variety of habitats.

Climates . Hind gills live in all seas and oceans. However, extreme inhabitants are species that live in arctic waters or colonize the Antarctic. In arctic waters z. B. the shaggy tree snail ( Dendronotus frondosus ) observed. On the shores of Spitsbergen was Coryphella verrucosa proven. Snails of the species Notaeolidia depressa have been found in coastal areas of the Antarctic .

Sea lemon ( Doris odhneri )

Depth . The life of snails is linked to their food sources. In this respect, for example, species that live directly or indirectly on photosynthetic plants are not expected to have any deep-sea records below the mesopelagial (below 1000 m). The majority of the snails live in the euphotic zone of the epipelagial , where photosynthesis takes place, the highest biodiversity and the highest bioactivity is recorded. However, there are indeed some hind gills that have adapted to life in deep sea areas. Here are a few examples. Species that live in tidal pools or shallow water areas include: a. Aplysia punctata , Onchidoris muricata (up to 15 m), Goniodoris castanea (up to 25 m). Species that live in the permanent flood zone are u. a. Tritonia plebeia (up to 130 m). Species that live below the lower tidal or permanent flood zone are u. a. Archidoris tuberculata (up to 300 m), Coryphella verrucosa (up to 450 m), broad-waxy thread snail ( Aeolidia papillosa ) (up to 800 m). Species that have been found in the deep sea include: a. Acteon hebes (800-4700 m), Acteon melampoides (400-4700 m).

Another extreme with regard to the water depth are permanent swimmers like the ocean- going Glaucus atlanticus . Due to swallowed air bubbles, he swims on his back and guided by ocean currents on the surface of the water.

Soil types . Mud and silt soils are mostly located near larger plant colonies, by coasts, in mud flats. They are populated by waste recyclers who extract nutrients from them, but also by prey hunters who hunt down small animals or dig up buried animals. Hard floors are substrates made of stones, planks, metal. They can be natural or artificial (piers, bridges, ship walls, sheet piling, sunken objects, etc.). Snail inhabitants of hard floors are u. a. Archidoris tuberculata or Acanthodoris pilosa . Rock bottoms occur on seabeds, but often also on rough coastlines. You will e.g. B. species furrows screw ( Janolus cristatus ) or thread screw ( Facelina coronata , Facelina bostoniensis ) inhabited.

Ground cover . Flat colonies of aquatic plants or sessile aquatic animals are often inhabited by thread snails.

Reproduction

Hind gills are hermaphrodites . They have so-called hermaphroditic glands, both of which produce germ cells that are necessary for reproduction.

Transfer of sperm cells In
contrast to the hermaphroditic real tapeworms , the hind gills are not self-fertilizers , but need a partner for the fertilization of the egg cells. When mating, both partners get close to each other, bring their sexual openings one above the other and perform a semen exchange. It can be that mating takes place alternately, i.e. both partners act as males and females. So-called mating chains also occur, especially when there is a high population density (e.g. in sea hares ), in which the rearmost animal only functions as a male, the frontmost animal only as a female and the animals in between as males and females.

Snail eggs

Dolabrifera : egg cells

As a result, egg cells are later secreted in gelatinous, protective covers in clusters or curled, twisted spawning cords or bands. The shells differ in consistency and firmness, the egg cells in abundance. In some species nutrients are added to the egg cells, or there are cells in the shells that serve as food depots during the maturation phase. The clutches are anchored to the ground or attached to stones or rocks. Near the coast they are deposited in places protected from waves. The spawning cords are attached to the ground, to algae, seaweed, seaweed, polyp sticks or otherwise, depending on the habitat.

Leminda millecra : spawning line

However, after laying, clutches and spawning lines are left to their own devices without further brood care. The number of egg cells secreted varies widely. Head shield snails of the species Retusa obtusa deposit around 50 eggs in up to four, and of the species Retusa truncatula around 700 eggs in a bottom layer. Thread snails of the species Facelina coronata lay up to 30,000 eggs, marine lemons of the species Archidoris tuberculata even lay up to 300,000 eggs in spawning lines.

Hexabranchus sanguineus : spawning band

The number of eggs and the quality of the jelly husks represent two fundamental development principles : quality versus quantity. While the bottom layers are well protected by layers and firmer shells, the eggs they contain are rich and supplied with nutrients for the budding snails, large numbers of spawning lines are available for mass production of simple eggs. In terms of the goal of survival as a population, however, none of the strategies can be selected as the clear winner. A few well-protected and stocked eggs are sufficient, as good precaution has reduced the loss rate per individual. However, the stock is less disaster-resistant. With many eggs the loss rate per individual is high. At the population level, however, this is compensated for by the large number of individuals and the possibility of broader distribution of the offspring: the survival of a few specimens is usually sufficient to maintain the population. In this respect, the “better choice” is locally dependent on the biotope.

From egg to snail

Dolabifera: Veliger larvae

Later, either fully developed juvenile snails (e.g. Retusa obtusa ) or so-called Veliger larvae hatch from the egg cells . The larvae are differently developed: some (e.g. Coryphella browni , Archidoris tuberculata ) hatch with protective small shells. Even species that are nudibranchs as adult snails often initially have a shell as larva (e.g. the sea angel Clione limacina ). After hatching, the Veliger larvae are distributed through the movement of water in the habitat (soil areas, algae and kelp forests, seagrass meadows). Either they stay there. Or they are driven away by currents, temporarily living as plankton before falling to the ground; so the snails open up u. U. even new habitats. Only after some drastic shape transformations the snails emerge from the larvae then in its final form.

Timing
A seed transfer does not happen with various species every time they meet, but at one or two mating times a year. The egg cells are not necessarily fertilized and released immediately during or after the sperm transfer , but sperm cells can be temporarily stored and the fertilized egg cells secreted at different times. The maturation of young snails or Veliger larvae takes from a few days to a few weeks, depending on the species. In the head shield snail Retusa obtusa , fully developed juvenile snails hatch after about four weeks. The Veliger larvae hatch in Retusa truncatula after a few days, in Flabellina affinis after five to eight days, in Coryphella browni after two weeks, in Janolus cristatus only after three weeks. The larval or plankton phase is also species-dependent and can even be a very long phase of life. In Aeolidia papillosa the plankton phase lasts a few weeks, in Archidoris tuberculata several months (life expectancy: around twelve months!). Winged snails (Pteropoda) even remain in the plankton for the rest of their lives.

nutrition

The forms of nutrition are not specific to the hind gill, but to the biotopes in which they live. There are therefore representatives for every form as well as mixed forms under the hind gills.

Residues recyclers feed on carrion and plant remains. They are often found in areas with loose soils, mud, silt, mud flats or in areas with organic segmentation. Species like the Retusa obtusa root through the soil.

Head shield snail Bullina lineata

Herbivorous snails ( herbivores ) feed u. a. from algae (from soils, stones, small algae colonizing plants to red, brown and green algae forests), kelp forests, seagrass meadows. You graze the plant stocks z. T. systematically. Examples of herbivores are the sea hare (e.g. Aplysia punctata ), the striped sea bladder ( Bulla striata ), and all butthree types of pancake snails . The latter have specialized in sucking out plant cells.

Carnivore snails ( carnivores ) exist in all associated orders. They feed on other animals such as B. boss animals , foraminifera , flatworms , bristle worms , sponges , cnidarians , tunicates , mussels , smaller species of snails, or even inferior specimens of their own species. Immobile marine animals such as colonies of bog animals, cnidarians, fields of sponges are grazed similarly to plants. Upright tree structures are usually browsed branch by branch. Movable prey, on the other hand, is hunted on migrations.

Eating takes place when the snails usually remove animal parts with their rasping tongues ( radula ). Some species such as Retusa obtusa , Philine aperta or Scaphander lignarius devour the much smaller prey as a whole and then chop it up in stomachs with chewing plates. In some of these species, therefore, regressions of the radula are recorded.

A Phyllodesmium horridum ( nudibranch ) in the sea off South Africa

An Elysia ornata ( gastropod snail )

An interesting phenomenon are snails, which can indirectly use photosynthesis for their own nutrition. There are various examples of this.

The snails of the genus Phyllodesmium ( Aeolidiidae ) feed on soft corals . When they eat, they also ingest the zooxanthellae (symbiotic, unicellular algae ) that live in symbiosis with them. The algae are not digested, but live on in the snail's intestine. Your intestine is almost full of the body, extends into the body processes and has a translucent outer skin. This allows light to reach the zooxanthellae inside and enable them to photosynthesize. The phyllodesmium can then utilize the carbohydrates produced by the algae and get along with almost no outside food.

Green velvet snails ( Elysia viridis ) or Hermaea dentritica feed u. a. of algae. When they soak up the contents of the algae cells, they also absorb pigment-containing chloroplasts ( organelles ); the chlorophyll then gives the snails a green color, which can also serve as camouflage; the chloroplasts taken over arecalled kleptoplasts . The organelles are distributed undestroyed through the branched midgut glands in the body and finally stored under the outer skin. In the snail, the stored organelles receive the starting materials for photosynthesis : light through the permeable outer shell, CO₂ as a byproduct of cell metabolism from the surrounding tissue, and water. They can therefore continue to function and produce high-energy hydrocarbons, but not in the long term: for Elysia viridis several weeks, for Hermaea dentritica only a few days. Then the organelles die and have to be replaced. In the case of Hermaea dentritica , the foreign organelles act like the replacement component of a hybrid drive: with them, the snail bridges the time until it develops new primary food (algae). The chloroplasts can only survive in the cells of the snail because a very unusual horizontal gene transfer has taken place between the plant cell and the animal cell.

Protection mechanisms

Like all water snails, hind gills have various potential predators, starting with conspecifics and larger snail species up to fish. This makes protective mechanisms necessary.

In the case of species with housings , the hard housings of different designs form a natural protection, as it were as a bunker carried along. Biological sensors that measure vibrations or water turbulence, react to changes in light or shadow, and even eyes form the associated early warning system.

Kleptocnid : Drummond's thread snail Facelina bostoniensis

A Pleurobranchaea meckelii ( Notaspidea ) in the Mediterranean

In the case of skin-breathing nudibranchs, however, this protection does not work in the absence of the housing. One possibility is to take away the desire to eat from the natural enemies by using poisons or caustic substances. Alternatively, dyes are used as a deterrent, dyes, surface patterns and shapes are used for camouflage, and repellants or dyes are expelled for defense purposes.

The poison used by many snails enters their bodies through food intake.

For example, some feed nudibranchs of sponges , which are inedible highly toxic and for other animals. However, the snails can ingest their toxins without harm and collect it in their external organs.

By absorbing the poison, the protective effect is transferred from the prey to the snail. Species that store poison become inedible and unattractive as prey. Examples are some magnificent snails (Chromodorididae) or warthog snails. In the case of other species, food experiments have shown that they produce poison themselves.

Janolus fuscus : Cerata with papillary

Some thread snails (Aeolidiidae) practice a similar method . They feed safely on nettle-reinforced corals and mollusks . The nettle capsules ( nematocytes ) of the prey reach their tips unharmed via the midgut processes that push themselves far into the numerous dorsal processes . There they are deposited in the body's own nettle sacks and henceforth serve for self-defense. They are shot down through nettle canals or activated when the cerata tips break. Since the snails do not make the nettle capsules themselves, they are known as kleptocnides (nettle thieves).

There are also a number of nudibranchs that produce caustic, acidic substances. The phyllids , a group within the star snails ( Doridoidea ), produce, for example, alkyl isocyanides , reactive compounds containing hydric acid; Flank-gill ( Notaspidea ) or the open sea almond ( Philine aperta ) produce sulfuric acid ; further examples are Archidoris tuberculata and Polycera quadrilineata . When touched or threatened, the corrosive substances are packed in skin secretions and secreted outwards by glands and thus spoil the attackers' desire for any contact.

Poisonous sea hare ( Aplysia gigantea ) and flank gill snails ( Pleurobranchaea maculata ) have caused the death of numerous dogs in Australia and New Zealand that licked or ate the snails on the beach. Pleurobranchaea even produces tetrodotoxin , a neurotoxin that is even with the puffer and blue-ringed octopus is.

If available, a striking external appearance in brightly colored colors is also not only decorative, but also very functional.

In connection with body toxins, the colors have a signal character . They are supposed to warn and deter attackers so that they don't get eaten in an emergency. The protection by deterrence but use not only poisons species but also some non-toxic. The latter also have striking colors, but only feign their toxicity.

Alternatively, colors, surface patterns and body shapes are also used for camouflage . For example, the per se colorless, transparent gullet snails of the species Hermea dentritica live on green algae, suck out pigment-containing chloroplasts from them with the nutrients, thereby taking on the color of the green algae and are therefore perfectly camouflaged. The Violet Fadenschnecke ( Flabelinae pedata ) and the Violet White tip Fadenschnecke ( Coryphella pedata ) have indeed on a neutral background a striking shape and color. But their habitat are u. a. Red algae forests. They are inconspicuous in terms of color, do not make a compact surface due to the many tentacle-like dorsal processes, and are therefore difficult to make out in underwater viewing conditions. Star snails of the species Peltodoris atromaculata have a white skin with black-rimmed dark brown spots of various sizes. On the sponges of the species Petrosia ficiformis they are not noticeable due to their color and leopard-like pattern.

Aplysia californica

Another protective mechanism is a diversionary maneuver . Sea hares emit a cloud of ink when touched. Some thread snails without embedded nettle capsules have cerata that are filled with unpleasant smelling substances (e.g. Phyllodesmium magnum ). Similar to lizards their tails, they can repel one or more appendages when touched. The rejected processes continue to contract. The smelly substance comes out after the waste and is distributed. This should irritate potential attackers and give the snail time to escape.

Development history

It is estimated that there are around 6,000 species today.

Systematics

The taxonomy of snails is subject to revision and change. Therefore there are different classifications. The one that goes back to J. Thiele (1929–1935) is usually considered classic . It was recognized until the 1990s. A more modern and the last one established on the basis of purely morphological approaches is that of Ponder and Lindberg (1997). The current system is phylogenetically oriented and goes back to Bouchet & Rocroi (2005).

Taxonomy by Bouchet & Rocroi (2005)

According to the taxonomy of Bouchet & Rocroi (2005) , the Opisthobranchia are an informal group within the clade of the heterobranchia :

Class Gastropoda G. Cuvier, 1797
- Klade Heterobranchia JE Gray, 1840
  - informal group of lower heterobranchia
  - informal group Opisthobranchia H. Milne Edwards, 1848
    - Klade Aplysiomorpha PH Fischer, 1883
    - Klade Cephalaspidea PH Fischer, 1883
    - Klade Gymnosomata HMD de Blainville, 1824
    - Klade Nudipleura H. Wägele & RC Willan, 2000
    - Klade Sacoglossa H. von Ihering, 1876
    - Klade Thecosomata HMD de Blainville, 1824
    - Klade Umbraculida WH Dall, 1889 (1827)
    - Group Acochlidiacea P. Bouchet & DR Lindberg, 2005
    - Group Cylindrobullida J. Thiele, 1931
  - informal group Pulmonata G. Cuvier in HDM Blainville, 1814

Compared to the taxonomy of Ponder & Lindberg (1997), there are u. a. the following differences:

the clade Cephalaspidea is smaller than the suborder Cephalaspidea,
the clade Nudipleura originated from the restructured suborder Nudibranchia and a family of the suborder Notaspidea ,
the clade Umbraculida was newly formed and placed as a sister group to the clade Cephalaspidea
the group Acochlidiacea was added,
the group Cylindrobullida was added, it contains a superfamily Cylindrobulloidea , which was previously assigned to the suborder Cephalaspidea,
the subordination of Notaspidea was dissolved; the families Tylodinidae and Umbraculidae were added to the superfamily Umbraculoidea in the clade Umbraculida; the family Pleurobranchidae was added to the superfamily Pleurobranchoidea ( subclade Pleurobranchomorpha, clade Nudipleura),
when adding families to new clades , missing sub-taxa were also generated.

The regroupings are the result of various phylogenetic but also morphological studies. a .:

the paraphyly of the suborder Cephalaspidea
the paraphyly of the subordination Notaspidea,
the subclades Nudibranchia and Pleurobranchomorpha form sister groups
the extensive monophyly of the group Acochlidiacea

showed.

Taxonomy by Ponder & Lindberg (1997)

According to the taxonomy of Ponder & Lindberg (1997) , the Opisthobranchia are an order within the superordinate order of the Diverse-Kiemer ( Heterobranchia ):

Class Gastropoda (snails) G. Cuvier, 1797
- Subclass Orthogastropoda WF Ponder & DR Lindberg, 1995
  - Subclass Apogastropoda L. Salvini-Plawen & G. Haszprunar, 1987
    - Superorder Heterobranchia JE Gray, 1840 / G. Haszprunar, 1985
      - Order Heterostropha (different-Dreher) PH Fischer, 1885
      - Order Opisthobranchia (hind gill snails) H. Milne Edwards, 1848
        
        Suborder Anaspidea (sea hare) PH Fischer, 1883
        
        Suborder Cephalaspidea (head shield snails) PH Fischer, 1883
        
        Suborder Gymnosomata (oar snails) HMD de Blainville, 1824
        
        Subordination Notaspidea (flank gill) PH Fischer, 1883
        
        Suborder Nudibranchia (Nudibranch) HMD de Blainville, 1814
        
        Suborder Sacoglossa (gastropods) H. von Ihering, 1876
        
        Suborder Thecosomata (Sea Butterflies) HMD de Blainville, 1824
      - Order Pulmonata (lung snails) G. Cuvier in HDM de Blainville, 1885

The changes from the previous taxonomy are due to morphological studies:

the problem of paraphyly of the prosobranchia was resolved
partially integrating the re-evaluation of the relationship between opisthobranchia and pulmonata

Traditional taxonomy

Older taxonomies go back to J. Thiele and use a tripartite division of the Gastropoda based on the respiratory organs. The Opisthobranchia form one of the main branches.

Gastropoda (snails)
- Prosobranchia ( Fore gill snails )
  - Archaeogastropoda ( adult snails )
  - Mesogastropoda ( middle snail )

literature

Hans A. Baensch / Robert A. Patzner: Mergus Sea Water Atlas. Volumes 2, 4 and 5, Mergus-Verlag, Melle.

Svein A. Fosså, Alf Jacob Nilsen: Coral reef aquarium. Volume 5, Birgit Schmettkamp Verlag, Bornheim, ISBN 3-86659-014-8 .

Coral. In: Marine aquarium specialist magazine. No. 26, April / May 2007, Natur und Tier Verlag Münster, ISSN 1439-779X .

Helmut Debelius / Rudie H. Kuiter : Nudibranchs of the oceans. Kosmos Verlag, ISBN 978-3-440-11133-8 .

Grell, K.-G. and IMF: Haminea hydatis (Opisthobranchia) - Embryonic Development. Publications on scientific films, Series 10, No. 47, 1977, IWF Göttingen, Biology Section, ISSN 0073-8417 , publication accompanying the film by the IWF , Göttingen.

Kathe R. Jensen: Phylogenetic Systematics and Classification of the Sacoglossa (Mollusca, Gastropoda, Opisthobranchia). In: Philosophical Transactions: Biological Sciences. Volume 351, No. 1335, pp. 91-122, London 1996, ISSN 0080-4622 .

Heike Wägele and Annette Klussmann-Kolb : Opisthobranchia (Mollusca, Gastropoda) - more than just slimy slugs. Shell reduction and its implications on defense and foraging. In: Frontiers in zoology. Volume 2, number 1, February 2005, p. 3, doi : 10.1186 / 1742-9994-2-3 , PMID 15715915 , PMC 554092 (free full text).

V. Vonnemann, M. Schroedl, A. Klussmann-Kolb and H. Wägele: Reconstruction of the phylogeny of the Opisthobranchia (Mollusca: Gastropoda) by means of 18S and 28S rRNA gene sequences. In: Journal of Molluscan Studies. Volume 71, No. 2, pp. 113-125, London 2005, ISSN 0260-1230 , doi : 10.1093 / mollus / eyi014 .

Fredy Brauchli: A hustle and bustle. In: Online magazine Naturally Life. 03/2005, pp. 26-31, PDF .

Kathe R. Jensen: Sacoglossa (Mollusca: Gastropoda: Opisthobranchia) from Singapore. In: The Raffles Bulletin of Zoology. Supl.No.22, pp. 207-223, December 20, 2009, PDF .

Seaslogforum: Phyllodesmium magnum, shedding the Ceratas ( memento of March 13, 2012 in the Internet Archive ), access February 11, 2010.

Web links

Commons : Opisthobranchia snails - Collection of images, videos and audio files

swell

^ H. Milne Edwards: Note sur la classifi ¢ cation naturelle des mollusques gaste¨ropodes . In: Annales des Sciences Naturelles. Paris (Series 3), Volume 9, 1848, pp. 102-112.

^ WB Rudman and RC Willan: Opisthobranchia. In: PL Beesley, GJB Ross and A. Wells (Eds.): Mollusca: the southern synthesis. Fauna of Australia. 2nd volumes, CSIRO, Melbourne 1998, ISBN 978-0-643-05756-2 , pp. 915-1035.

↑ C. Grande, J. Templado, J. Lucas Cercera and R. Zardoya: Molecular Phylogeny of Euthyneura (Mollusca: Gastropoda). In: Molecular Biology and Evolution. Volume 21, No. 2, 2004, pp. 303-313, doi : 10.1093 / molbev / msh016 .

↑ Southern Ocean Mollusc Database (SOMBASE) ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.

↑ Bill Rudman: Aplysia gigantea on seaslugforum.net.

^ National Institute of Water and Atmospheric Research: Toxic Sea Slugs .

^ Johannes Thiele : Handbook of systematic molluscology . 2 volumes. 1929-1935; English translation: R. Bieler and PM Mikkelsen (scientific editing); JS Bhatti (translator): Handbook of systematic malacology. Publ: Washington, DC; Smithsonian Institution Libraries; National Science Foundation; 1992–. Part 1: Loricata; Gastropoda: Prosobranchia; Part 2: Gastropoda: Opisthobranchia and Pulmonata; Part 3: Scaphopoda / Bivalvia / Cehalopoda; Part 4: Comparative Morphology / Phylogeny / Geographical Distribution.

↑ Winston F. Ponder and David R. Lindberg : Towards a phylogeny of gastropod molluscs: an analysis using morphological characters. In: Zoological Journal of the Linnean Society. Volume 119, No. 2, 1997, pp. 83-265, doi : 10.1111 / j.1096-3642.1997.tb00137.x

↑ P. Bouchet and J.-P. Rocroi: Part 2. Working classification of the Gastropoda. In: Malacologia. Volume 47, pp. 239-283, Ann Arbor 2005, ISSN 0076-2997 , archive.org , ConchBooks, ISBN 978-3-92591972-5 .

↑ P. Bouchet and J.-P. Rocroi (eds.): J. Frýda, B. Hausdorf, WF Ponder, Á. Valdés and A. Warén: Classification and nomenclator of gastropod families. In: Malacologia: International Journal of Malacology. Volume 47, No. 1–2, ConchBooks, Hackenheim 2005, ISBN 3-925919-72-4 , ISSN 0076-2997 , http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278

↑ GT Poppe and SP Tagaro: The New Classification of Gastropods according to Bouchet and Rocroi, 2005. February 23, 2006 PDF ( Memento of the original from September 27, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2
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