Nassarius pullus, common names : black nassa; olive dog whelk; ribbed dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.
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Remains from a time in the current warm period when the sea level was higher are called the Dog whelk layers (Nákuðungslögin), seen especially in Hunaflói and Eyrarbakki and Stokkseyri. The layers contain typical coastal fauna with dog whelk (Nucella lapillus) and periwinkles most prominent.
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The dog whelk lives in rocky shores, and estuarine conditions. Climatically it lives between the 0 °C and 20 °C isotherms.
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The dog whelk, dogwhelk, or Atlantic dogwinkle (scientific name Nucella lapillus) is a species of predatory sea snail, a carnivorous marine gastropod in the family Muricidae, the rock snails. Nucella lapillus was originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae as Buccinum lapillus (the basionym). "Dog whelk" can also refer to the Nassariidae.
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In the dog whelk, the growth of a penis in imposex females gradually blocks the oviduct, although ovule production continues. An imposex female dog whelk passes through several stages of penis growth before it becomes unable to maintain a constant production of ovules. Later stages of imposex lead to sterility and the premature death of the females of reproductive age, which can adversely affect the entire population.
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Nassarius glans, common name the acorn dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.
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Certain carnivorous gastropod snails such as whelks (Buccinidae) and murex snails (Muricidae) feed on bivalves by boring into their shells, although many Busyconine whelks (e.g., Busycon carica, Sinistrofulgur sinistrum) are "chipping-style" predators. The dog whelk (Nucella lamellosa) drills a hole with its radula assisted by a shell-dissolving secretion. The dog whelk then inserts its extendible proboscis and sucks out the body contents of the victim, which is typically a blue mussel.
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Nassarius coronulus, common name the small crown dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.
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Tritia reticulata, common name the "netted dog whelk", is a species of small European sea snail, a marine gastropod mollusc in the family Nassariidae, the dog whelks or nassa mud snails.
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Nassarius conoidalis, common name the cone-shaped Nassa or the jewelled dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the nassa mud snails.
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Nassarius coronatus, common name the crown nassa or the coronated dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.
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Wave action tends to confine the dog whelk to more sheltered shores, however, this can be counteracted, both by adaptations to tolerate it such as the shell and muscular foot, and by the avoidance of direct exposure to wave action afforded by making use of sheltered microhabitats in rocky crevices. The preferred substrate material of the dog whelk is solid rock and not sand, which adds to its problems at lower levels on the shore where weathering is likely to have reduced the stability of the seabed. Water loss by evaporation has to be tolerated (by means of the operculum which holds water in and prevents its escape as vapour), or avoided (by moving into water or a shaded area). The peak in dog whelk population density is approximately coincidental with the mid-tidal zone.
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The Nassariidae, Nassa mud snails (USA), or dog whelks (UK), are a taxonomic family of small to medium-sized sea snails, marine gastropod mollusks in the clade Neogastropoda. "Dog whelk" also refers to Nucella lapillus.
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Tidal pools and comparable microhabitats extend the vertical range of organisms such as the dog whelk as they provide a more constant environment, but they are prone to increased salinity because evaporation concentrates dissolved substances. This can create toxic conditions for many species. The dog whelk can only survive out of water for a limited period, as it will gradually become desiccated and die if emersed for too long. Metabolic processes within cells take place in solution, and a decrease in water content makes it impossible for the organism to function properly.
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Predators of the dog whelk include various species of crabs and birds. Protection against predation from crabs which attempt to pull the soft body out through the shell aperture can be afforded by growing teeth around the edge of the aperture. Many predators cannot smash the strong shell of an adult dog whelk, but juveniles are vulnerable to attack from many predatory species. Eider ducks and various other birds simply swallow the entire body with its shell, while oystercatchers and various crustaceans are often capable of crushing or breaking the shells.
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Marine mussels are eaten by humans, starfish, seabirds, and by numerous species of predatory marine gastropods in the family Muricidae, such as the dog whelk, Nucella lapillus. Freshwater mussels are eaten by muskrats, otters, raccoons, ducks, baboons, humans, and geese.
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In the winter they endure more predation from purple sandpipers and similar wading birds, but in the summer crabs represent a greater threat. In general, the dog whelk can be thought of as being vulnerable to birds when emersed, and to crabs when immersed.
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Exposure to organotin compounds causes the development of male accessory sex organs in female prosobranch gastropods. This phenomenon has been termed imposex. TBT has been shown to affect invertebrate development. Marine snails, such as the dog whelk (Nucella lapillus), has often been used as an indicator species.
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In the British Isles, Belgium and the Netherlands (wulk/wullok), the word is used for a number of species in the family Buccinidae, especially Buccinum undatum, an edible European and Northern Atlantic species. In the British Isles, the common name "dog whelk" is used for Nucella lapillus (family Muricidae) and for Nassarius species (family Nassariidae).
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There were also bones from red deer and birds and an antler harpoon for catching a wide range of fish, including cod, mackerel, haddock, herring and salmon. Fine beads had been made from seashells, while ochre pigment and a particular species of dog whelk that may have been used for the extraction of purple dye suggest concern with decoration.
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It lives in the middle shore. In general it can be said that at high vertical heights on the shoreline the dog whelk is most threatened by biotic factors such as predation from birds and interspecific competition for food, but abiotic factors are the primary concern, creating a harsh environment in which it is difficult to survive. At low vertical heights it is biotic factors, such as predation from crabs and intraspecific competition, which cause problems. The upper limit of the range in which the dog whelk is generally found is approximately coincidental with the mean high water neap tide line, and the lower limit of the range is approximately coincidental with the mean low water neap tide line, so that the vast majority of dog whelks are found on the mid-tidal zone.
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In experiments it has been shown that 50% of dog whelks die at 40 °C, and it can be assumed that at temperatures lower than this a smaller proportion will be killed off. Furthermore, the dog whelk has to excrete ammonia directly into water, as it does not have the adaptation possessed by many upper shore species which would allow it to produce uric acid for excretion without loss of water. When kept emersed for seven days at a temperature of 18 °C, 100% of dog whelks die, in contrast to many periwinkle species which can lose even more water than the dog whelk (i.e. more than 37% of their total body mass) but survive as a result of their ability to excrete toxic waste products more efficiently.
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This allows shelter until more food is required, when foraging resumes. If waves are large or there is an excessive risk of water loss the dog whelk will remain inactive in sheltered locations for long periods. Mussels have developed a defensive strategy of tethering and immobilising with byssus threads any dog whelks invading their beds, leading to the whelks' starvation.
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Objects carved from bone include spatulas and toggles. A handle was made from red deer antler, and pendants were made from horse and dog teeth. Pointed bone tools were carved from sheep tibiae or roe deer metapodials. Shells had been perforated for use as pendants, using shells from Nucella lapillus (dog whelk), and Littorina obtusata – both of which species had to be transported from the coast.
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Some species are polymorphic for different chromosome structural forms. The structural variation may be associated with different numbers of chromosomes in different individuals, which occurs in the ladybird beetle Chilocorus stigma, some mantids of the genus Ameles, the European shrew Sorex araneus. There is some evidence from the case of the mollusc Thais lapillus (the dog whelk) on the Brittany coast, that the two chromosome morphs are adapted to different habitats.
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The capability of shell thickening by mussels has become a very effective defense mechanism. In the presence of predators a mussel is able to increase shell thickness 5 to 10 percent, which in turn makes opening the shell take 50 percent more time. Small mussels are also eaten by the dog whelk, Nucella lapillus. The blue mussel is host to a wide range of parasites, but these parasites usually do not cause much damage.
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One common example is it leaching from marine paints into the aquatic environment, causing irreversible damage to the aquatic life. Tributyltin has also been linked to obesity in humans, as it triggers genes that cause the growth of fat cells. Tributyltin is harmful to some marine organisms, including the dog whelk, it causes dog whelks to suffer from imposex; females develop male sexual characteristics such as a penis. This causes them to become infertile or even die.
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Some organotin compounds are relatively toxic, with both advantages and problems. They are used for biocidal properties as fungicides, pesticides, algaecides, wood preservatives, and antifouling agents. Tributyltin oxide is used as a wood preservative. Tributyltin was used as additive for ship paint to prevent growth of marine organisms on ships, with use declining after organotin compounds were recognized as persistent organic pollutants with an extremely high toxicity for some marine organisms (the dog whelk, for example).
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The beaches and cliffs around the mouth of the River Camel are home to a variety of marine molluscs, and on beaches exposed to longshore drift one can also find shells washed up with the tide, particularly after westerly storms. Common limpet, blue mussel and the barnacle (Chthamalus stellatus) are commonly found on rocks that are covered at high tide, with dog whelk and common periwinkle found in tidal rockpools. The banded wedge shell and blunt tellin (Arcopagia crassa) can also be found as far upstream as Padstow.
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This is a small hermit crab which tends to occupy shells of the netted dog whelk Tritia reticulata. These crabs are often present on flattish beaches composed of medium to fine grained sand where the waves sweep up the shore. When exposed, they rapidly bury themselves in the sand, using the enlarged left chela to stabilise themselves in the wet sand and limit the extent to which they are rolled about by the waves. Near Cádiz in southern Spain, there are three species of hermit crab, D. pugilator, Paguristes eremita and Pagurus forbesii.
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Tributyltin (TBT) hydride model It was believed that the only inducer of imposex was tributyltin (TBT),Ruiz JM, Quintela M, Barreiro R (1998) Tributyltin and imposex: no uncertainty shown. Mar Ecol Prog Ser 170: 293–294 which can be active in extremely low concentrations, but recent studies reported other substances as inducers, such as triphenyltin and ethanol. Tributyltin is an anti-fouling agent for boats which affects females of the species Nucella lapillus (dog whelk), Voluta ebraea (the Hebrew volute), Olivancillaria vesica, Stramonita haemastoma (red- mouthed rock shell) and more than 200 other marine gastropods.
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In 1946, French archaeologist Francoise Henry excavated evidence of a 7th-century AD dye workshop on Inishkea North where the monks in an early Christian Monastery were producing it from the shells of the dog whelk The dye fetched high prices at the time it was in high demand. One letter in the Book of Kells would take 500 shells to get enough colour to decorate it. Purple was very important because in early Irish laws only the royalty could wear purple. The tradition came from the Roman tradition, who took it from the Greeks, who borrowed that tradition from the Phoenicians.
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TBT has been shown to harm many marine organisms, specifically oysters and mollusks. Extremely low concentrations of tributyltin moiety (TBT) causes defective shell growth in the oyster Crassostrea gigas (at a concentration of 20 ng/l) and development of male characteristics in female genitalia in the dog whelk Nucella lapillus (where changes in gonad characteristics are initiated at 1 ng/l). The international maritime community has phased out the use of organtin-based coatings. This phase-out of toxic biocides in marine coatings posed a severe problem for the shipping industry; it presents a major challenge for the producers of coatings to develop alternative technologies.
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The primary marine conservation features of Laxey Bay are maerl beds to the north and east, eelgrass meadows in Garwick Bay, kelp forest, rocky reef, the dog whelk (Nucella lapillus) population and relatively large numbers of the long-lived bivalve, the ocean quahog (Arctica islandica). Thornback ray, spotted ray and small-spotted catshark eggcases are regularly found on Garwick Beach, suggesting nearby breeding populations. Laxey Bay is also notable for its seabird populations, including breeding shag, black guillemot, Eurasian eider, herring gull, great black-backed gull and small numbers of lesser black-backed gull. red-billed chough, peregrine, Eurasian oystercatcher, Eurasian curlew, great cormorant, grey heron and northern fulmar are also commonly seen.
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Its adaptations include a modified radula (a toothed chitinous structure) to bore holes in the shells of prey, complemented by an organ on the foot which secretes a shell- softening chemical. When a hole has been formed paralysing chemicals and digestive enzymes are secreted inside the shell to break the soft body down into a 'soup' which can be sucked out with the proboscis. The plates of barnacles can be pushed apart with the proboscis, and the entire individual is eaten in about a day, although larger animals such as mussels may take up to a week to digest. Feeding only occurs when conditions are conducive to such an activity, and during these times the dog whelk consumes large quantities of food so that the gut is always kept as full as possible.
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