Neptunea Antiqua Research Articles

Late Pleistocene boreal molluscs in the Gulf of Cadiz: Past and current oceanographic implications

Remains of molluscs were collected from the seafloor on the north-eastern margin of the Gulf of Cadiz, between 300 and 1000 m water depth, using different sampling methods (e.g. dredging, trawling and box-coring), during several deep-sea expeditions. Samples contained a suite of species which nowadays mostly occur northwards of the English Channel, together with other widespread species. Species now locally extinct in the Gulf of Cadiz and restricted to northern latitudes, which unequivocally indicate a faunal shift, include the gastropods Buccinum undatum, Colus gracilis, Liomesus ovum and Neptunea antiqua, the bivalves Arctica islandica, Chlamys islandica, Modiolus modiolus, Mya truncata and Nuculana pernula and the scaphopod Antalis entalis. These species represent “Boreal Guests” of marked palaeoclimatic significance, some of which are reported for the first time in the Gulf of Cadiz. The boreal species collected were mostly large (>5 cm) whereas smaller boreal species were extremely scarce, probably winnowed away by strong bottom currents. The pteropod Limacina retroversa, at present restricted to water masses northwards of the Iberian Peninsula but widespread in Mediterranean sediments of the last glaciation, was also recorded. Accelerator mass spectrometry (AMS) 14C dates obtained from nine specimens of molluscs ranged between 26.1 and 14.6 kyr B.P., thus confirming their attribution to a last glacial assemblage. The abundance of these molluscan remains in the present Mediterranean Outflow Water pathway could be explained if this outflow was reduced in intensity or more likely shifted to a deeper level, leaving the upper slope in contact with suitable Atlantic intermediate waters. The findings of Boreal Guests in the Gulf of Cadiz document the continuity of the faunal shift which is well-known in the Mediterranean basin. Species still living in the Gulf of Cadiz and the Alboran Sea nevertheless account for 84.6% of specimens among the larger species.

Importance of discards from the English Nephrops norvegicus fishery in the North Sea to marine scavengers

Discards refer to that part of the catch which is returned to the sea during commercial fishing operations. Organisms that do not survive the discarding process can provide an additional food source to scavenging species. The aim of this study was to determine whether the quantity and quality of discarded material from the intensively fished English Nephrops norvegicus fishery is such that it has a positive effect on marine scavenger populations. Field studies were used to identify marine scavenger species and estimate their abundance. Discard experiments combined with data from commercial vessels provided estimates of the partitioning of discards between aerial and marine scavengers and the spatial distribution of discarding. A bioenergetic model was devised to evaluate the importance of discards to marine scavengers. Seabirds utilised an estimated 57% of the discarded material; most discarding (83%) took place over the fishing grounds. Species identified as marine dis- card scavengers included Liocarcinus depurator, Asterias rubens, Neptunea antiqua, Pagurus bern- hardus, Carcinus maenas, Cancer pagurus and Myxine glutinosa. The hagfish M. glutinosa was the most abundant scavenger, and made up 79% by weight of all identified marine scavengers on the fishing grounds. The energy available from discards could potentially provide the identified marine discard scavengers on the fishing grounds with 37% of their energetic requirements during the fish- ing season. This level of contribution is probably sufficient to allow larger populations of these scavenging species to exist than would otherwise be possible.

Evaluation of the age of the red whelk Neptunea antiqua using statoliths, opercula and element ratios in the shell

Growth rings present in whole and sectioned statoliths were used to determine the age of red whelks Neptunea antiqua, from the North Sea. Validation of the periodicity of the rings was established in four whelks by comparing the number of statolith rings with the number of seasonal Mg:Ca ratio cycles present in shell calcium carbonate samples drilled sequentially from along the growth axis. There was exact correspondence between the number of growth rings and the number of element ratio cycles in two of the shells and a 1-year difference in the estimated age between the two methods in the other two shells, evidence which is strongly indicative of an annual periodicity of deposition to the statolith rings. The estimated age of the whelks using the statolith rings varied between 4 years (shell length 102 mm) and 17 years (shell length 148 mm). The age of the whelks ascertained from the statoliths was compared with age estimates from the number of adventitious layers in sectioned opercula. The number of adventitious layers in whelks from 51 to 148 mm shell length ranged between 1 and 12 years. No significant difference was observed between the number of strongly defined statolith rings and number of opercula adventitious layers.

Imposex and organotin concentrations in Buccinum undatum and Neptunea antiqua from the North Sea: relationship to shipping density and hydrographical conditions

The presence and the development of imposex were investigated in the common whelk ( Buccinum undatum) and the red whelk ( Neptunea antiqua) from the open North Sea and the Skagerrak. Imposex development was related to levels of organotins in snails and in the fine fractions (<63 μm) of the sediments they inhabit. The sampling locations were classified according to three levels of traffic densities of ships of ⩾100 gt per day passing within 15 Nautical miles of the sampling station, shipping levels being: high (>10 ships day −1), intermediate (5–10 ships day −1), and low (<5 ships day −1). Sampling stations were also classified according to presence or absence of a vertically stratified water column. In the snails the body levels of the butyltin metabolites MBT and DBT and the parent phenyltin compound TPT, were higher than those of TBT and PT metabolites. In the sediment, the parent compounds and the mono-substituted metabolites MBT and MPT were present in the highest concentrations. The highest body levels of all organotin compounds and the highest imposex indices for the common whelk were found at those locations in the Southern Bight and the German Bight that had a high shipping density as well as a homogeneously mixed water column during the whole year. At these locations sediment levels of organotins were also higher than at other sites. In contrast, the body levels of organotins were low and imposex was sometimes even completely absent in snails from stratified deep-water stations in the Skagerrak, despite a very high shipping density in the entrance area of the Baltic. In sediments from stratified locations with low or intermediate shipping densities, organotin compounds were below or close to their respective limits of detection. These stations were located in areas with a stratified water column during the whole year. The results can be explained by postulating a much higher resistance for dissolved organotins to migrate through a pycnocline. Organotins could only transgress through a pycnocline when adsorbed to settling particles that manage to transgress the boundary between layers. N. antiqua could only be obtained in sufficient numbers from deeper water stations, which almost all had a stratified water column. At stations where both snail species were obtained and imposex was present, the imposex index was higher in the red whelk. Hence N. antiqua seems to be the more sensitive species of the two. In the red whelk, imposex development increased with shipping density too, though in the smaller samples the trend was not significant. Average biota-sediment accumulation factors (BSAFs; normalised for lipid content in snails and TOC content in the fraction <63 μm in sediments) for Buccinum ranged from 0.4 to 1.0 for butyltins and were similar to literature values reported for TBT in other marine species. Higher average BSAF values were found for phenyltins 1.5 (MPT) to 17 (TPT). The high values for TPT match the ranges expected from equilibrium partitioning concepts of persistent hydrophobic compounds. The ratio of live snails to the total number of live snails plus empty shells ranged between 2.5 and 93%. This parameter might be a useful indicator to compare past and present densities of populations of both species in different areas of the North Sea.

Utilisation of invertebrates discarded from the Nephrops fishery by variously selective benthic scavengers in the west of Scotland

Demersal trawl fisheries generate large quantities of discards which temporarily increase the amount of carrion available to benthic communities and lead to a faster energetic turn- over. This study examines the availability of discarded material to the benthos, assesses consumption times of different items and identifies scavengers attracted to those invertebrates most frequently dis- carded from Clyde Sea Nephrops trawlers. In field and laboratory trials, heavy-shelled dead whelks (Buccinum undatum, Neptunea antiqua) sank faster than softer-bodied species like cephalopods (Allotheuthis subulata, Rossia macrosoma) or echinoderms (Ophiura ophiura, Asterias rubens), mak- ing most discards available to the benthos (at ca. -60 m CD (chart datum)) within minutes after dis- carding. SCUBA and time-lapse camera observations in the Clyde Sea and Loch Sween indicated bait utilisation times between 24 and 48 h. Fast-moving animals like brachyuran crabs were the first to arrive at discard bait piles whose composition mimicked typical discards from the Clyde Sea Nephrops fishery. Bimonthly deployments of traps baited with invertebrate discards in the north of the Clyde Sea showed that A. rubens, followed by Pagurus bernhardus, Liocarcinus depurator and whelks, were the most abundant megafaunal scavengers. Fine-meshed funnel traps deployed inside those creels yielded up to 2819 amphipods per trap, with Scopelocheirus hopei and Orchomene nanus accounting for most of the catch. Together with whelks, A. rubens and Carcinus maenas, O. nanus showed a clear preference for crustacean bait. By contrast, Pagurus bernhardus was more attracted to A. rubens and, in 1 trial, to O. ophiura bait. Traps deployed in the south of the Clyde Sea yielded generally lower numbers and species diversity in the catch, with Nephrops being the most abundant megafaunal scavenger. It showed a preference for L. depurator and conspecific bait. While the results show that a range of epibenthic species readily utilise invertebrates discarded from Clyde Sea Nephrops trawlers, it is unknown to what extent discards subsidise benthic communities as infor- mation on the ecological energetics of the species involved locally is currently lacking.

Imposex in two sublittoral neogastropods from the Kattegat and Skagerrak: the common whelk Buccinum undatum and the red whelk Neptunea antiqua

Imposex development in female whelks (Prosobranchia: Neogastropoda) has been sug- gested as a bioindicator of tributyltin (TBT) pollution in the marine environment. The occurrence of imposex in the common whelk Buccinum undatum and the red whelk Neptunea antiqua in sublittoral areas of Danish waters was related to organotin levels. In contrast, imposex was absent in reference material of N. antiqua collected in the area before 1938. The concentrations of TBT in whole body tissue of B. undatum ranged from <0.2 to 3.1 ng Sn g -1 and total butyltin (∑ BT = TBT + DBT + MBT) ranged from 1.2 to 32.9 ng Sn g -1 wet weight. The intensity (i.e. frequency and severity) of imposex was generally higher in N. antiqua than in B. undatum. At 14 stations in the Kattegat and Skagerrak, imposex was present in 9 to 89% of B. undatum and 67 to 100% of N. antiqua. N. antiqua seems to be more sensitive to TBT and would thus be the better bioindicator.

The seasonality and role of the neurotoxin tetramine in the salivary glands of the red whelk Neptunea antiqua (L.)

The red whelk Neptunea antiqua (family Buccinidae) is a sublittoral species of marine prosobranch mollusc that occurs in the cold temperate waters of the Eastern Atlantic Boreal Region. A clearly defined seasonal cycle was revealed in the concentration of the whelk's salivary gland neurotoxin, tetramine, ranging from undetectable levels to 6530 μg/g over the course of an annual sampling period in the central western Irish Sea. Concentrations of this amine were indirectly related to feeding activity through the use of digestive gland indices. Additionally, laboratory observations confirmed the suspected ability of these whelks to actively predate on bivalves, supporting the use of this toxin in food procurement.

The Significance of Imposex Levels and TBT Contamination in the Red Whelk, Neptunea antiqua (L.) from the Offshore Irish Sea

The extent to which open seas and oceanic waters have been contaminated by TBT is unclear since most sampling programmes have concentrated on inshore areas, particularly near harbours. Accordingly, the red whelk, Neptunea antiqua L. (Mollusca: Prosobranchia), a sublittoral and dioecious prosobranch species, was selected to investigate the potential effects of TBT-induced imposex in the central western Irish Sea. The presence of imposex was noted in >90% of all female whelks that were examined on a monthly basis over a 12-month period. However, the proliferation of the vas deferens was not considered severe enough to affect the reproductive capabilities of the population. Low concentrations of butyltins were detected in the soft tissues of all whelks examined, ranging from 0.009 to 0.112 μg g−1 Sn dry wt There was no significant correlation between the documented imposex stages and total butyltin contamination, indicating that the species is not a reliable bioindicator species of the effects of this contaminant.

Seasonal patterns in the reproductive activity of the red whelk, Neptunea antiqua (Mollusca: Prosobranchia) in the Irish Sea

The red whelk, Neptunea antiqua (Mollusca: Prosobranchia) is a dioecious prosobranch species with internal fertilization, and lecithotrophic larval development. Sexual dimorphism, sexual ratio, the size and age at sexual maturity, and the annual breeding and hatching periods of this subtidal neogastropod were investigated in the central western Irish Sea. Sexual dimorphism was evident as female whelks were larger in both length and weight. Subtle differences in shell morphology were also detected between the sexes. All samples taken together indicated an equal male to female sexual ratio for the studied population. Size and age at sexual maturity were noted to differ between sexes, occurring at 75–90 mm (shell length), or four to five years in males, and 95–110 mm, or six to nine years in females. Quantitative and qualitative techniques identified an annual spawning period between late spring and early summer. Egg masses containing between 14 and 84 egg capsules were observed attached to the dorsal surface of whelk shells in the succeeding months. An average fecundity of 63·78 juveniles was estimated per egg mass deposited. Juveniles were observed to hatch after 6–7 months in laboratory maintained aquaria, indicating a hatching period from October to January in the Irish Sea.

Impact of scallop dredging on benthic megafauna: a comparison of damage levels in captured and non-captured organisms

The impact of scallop dredging on benthic megafauna was assessed by direct observation of damage, both in the bycatch and in organisms encountering dredges but not captured. Damage was assessed using a simple 4- point scale adapted for different taxonomic groups. Experi- mental dredging was undertaken on a scallop fishing ground in the north Irish Sea, off the Isle of Man. Divers were deployed immediately after dredges had passed, to record levels of damage to megafauna left in the dredge tracks. Mean damage levels, and the proportions of the 4 damage scores in the bycatch and on the seabed, were the same in most species. Some common species did show differences. The edible crab Cancer pagurus was more severely damaged when not captured, while the starfish Asterias rubens and whelk Neptunea antiqua received greater damage within the bycatch. Capture efficiency for the megafauna was low, rang- ing from 2 to 25% among species. The results indicate that the majority of damage to large benthic invertebrates during scallop dredging occurs unobserved on the seabed, rather than in the bycatch.

Imposex in the whelks Buccinum undatum and Neptunea antiqua from the west coast of Scotland

Whelks, Buccinum undatum and Neptunea antiqua, collected from three sites on the west coast of Scotland during 1997 showed varying degrees of imposex. Both the incidence of imposex and the degree of imposex development in individuals was greater in N. antiqua than in B. undatum. The results probably reflect long-term contamination of sediments with tributyltin (TBT) originating from inputs prior to its prohibition for use as an antifoulant on small boats and salmon nets in 1987, but indicate the potential for use of these deeper water whelks as bioindicators of continuing TBT pollution. The levels of imposex found were not such as to affect the fishery potential of the species in Scottish west coast waters.

Tributyltin: Case study of an environmental contaminant

Whelks, Buccinum undatum and Neptunea antiqua, collected from three sites on the west coast of Scotland during 1997 showed varying degrees of imposex. Both the incidence of imposex and the degree of imposex development in individuals was greater in N. antiqua than in B. undatum. The results probably reflect long-term contamination of sediments with tributyltin (TBT) originating from inputs prior to its prohibition for use as an antifoulant on small boats and salmon nets in 1987, but indicate the potential for use of these deeper water whelks as bioindicators of continuing TBT pollution. The levels of imposex found were not such as to affect the fishery potential of the species in Scottish west coast waters.

Accumulation of organotin compounds in the common whelk Buccinum undatum and the red whelk Neptunea antiqua in association with imposex

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 152:197-203 (1997) - doi:10.3354/meps152197 Accumulation of organotin compounds in the common whelk Buccinum undatum and the red whelk Neptunea antiqua in association with imposex Ide I, Witten EP, Fischer J, Kalbfus W, Zellner A, Stroben E, Watermann B Several species of the subclass Prosobranchia are considered to be suitable organisms for monitoring long-term effects of triorganotin (TOT) compounds. This study utilized Buccinum undatum and Neptunea antiqua from the North Sea and the Irish Sea. Morphological alterations in the genital system (imposex phenomena), the histological structure of the gut, and the gonads were studied. TOT concentrations in soft body tissue and shells were determined. Females of both species displayed imposex phenomena (pseudohermaphroditism). The percentage of altered females per station ranged from 0 to 90% in B. undatum and from 0 to 29% in N. antiqua. Imposex index values in B. undatum reached 1.09 near Helgoland and 0.86 in N. antiqua sampled at 25 nautical miles from the Scottish northeast coast. Organotin compounds were detected in the soft bodies of snails from all stations. A chi-square analysis revealed a significant correlation between imposex stages and TOT concentrations in B. undatum but not in N. antiqua. Tributyltin (TBT) in B. undatum ranged from 1.0 to 15.9 ng g-1 wet weight (Irish east coast). TBT concentrations in N. antiqua were higher and ranged from 2.2 to 25.7 ng g-1. In both species, organotin compounds in the shells were below detection limits. Despite high TBT concentrations in soft tissues and the occurrence of imposex (offshore and inshore), female gonads were in good shape and no signs of limited reproductive capacity were found. Histological findings indicate that TBT does not contribute considerably to mortality in the common whelk. Molluscs · Organotin compounds · Accumulation · Imposex · Antifouling · Deep sea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 152. Publication date: June 26, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Responses of two proboscis muscles of Neptunea antiqua (mollusca) to some calcium antagonist drugs

1. Both the radular retractor (RR) and radular sac (RS) muscles of Neptunea antiqua depend upon [Ca] 0 to raise the internal calcium concentration of the contractile elements to activation level. 2. The K- and ACh-induced responses of the muscles were strongly inhibited in calcium-free seawater. 3. Calcium antagonist drugs were more inhibitory on ACh-induced responses than on K-responses suggesting a dichotomy of calcium channel activities modulated by these agonists. 4. The calcium ionophore A23187 enhanced ACh-induced responses of both muscles but was without effect on K-induced responses. 5. The responses of these Neptunea muscles to calcium antagonist drugs show some similarities but also differences to those of Buccinum muscles and are quite unlike the excitation induced by organic antagonists in similar muscles of the American whelk Busycon canaliculatum.

The influence of salinity acclimation on the temperature sensitivity of oxygen binding to the haemocyanin of the prosobranch Neptunea Antiqua

ABSTRACT The thermal sensitivity of oxygen binding has been studied at 10, 15, 20 and 25 °C in whole blood from specimens of Neptunea antiqua acclimated to ambient salinities of 24 and 35 ‰. The O2 affinity is strongly pH-dependent, demonstrating a large reversed Bohr shift below pH 8.0. The magnitude of the Bohr shift is not significantly influenced by temperature or ionic concentration. At 35 ‰, the blood O2-affinity is strongly influenced by temperature (ΔHapp≈ −58.6 kJ mol−1), while at 24 ‰ there is almost no temperature sensitivity (ΔHapp&amp;lt;−18.8 kJ mol−1).

The occurrence of the eunicid polychaetesIphitime cuenotiFauvel andI. PaguriFage &amp; legendre in crabs from the Scottish West Coast

Abstract During an investigation into the occurrence of various crab species in the Oban (West of Scotland) area, Iphitime cuenoti was found infesting the branchial cavity of Liocarcinus puber, L. corrugatus, L. depurator, Carcinus mamas, Cancer pagurus, Hyas araneus and Macropodia longirostris caught within, or on the sandy mud below, the Laminaria forest. The same crab species obtained from sandy habitats, and crabs peculiar to such a habitat (Portumnus latipes, Liocarcinus holsatus and Corystes cassivelaunus) did not harbour the polychaetes. Three or more worms were commonly found in each Liocarcinus host, the highest number recorded, in L. puber, comprising 9 adult and at least 98 juveniles, the latter being found between the gill lamellae. Over 90% of both L. puber and L. corrugatus were infested, 35% of L. depuratot, but less than 10% of any of the other species. The largest worms (up to 80 mm alcohol-preserved length) were found in L. puber and L. corrugatus. Worms were found to have either simple or slightly bifurcate branchiae, or multifurcate branchiae. Worms with simple branchiae rarely reached 40 mm in length, usually possessed jaws which exceeded 700 μm in length, and were never found to contain eggs. These are regarded as putative males, and histological evidence from three specimens confirms this suggestion. Only Iphitime with multifurcate branchiae were found to contain eggs, and were also the largest worms, but their jaw length was very variable, ranging from 0-1030 μm with little or no relationship to the length of the worm. The smallest worms, 3 mm in length, were found between the gill lamellae throughout the year, but mainly from December to August. In multiple infestations there appeared to be one dominant female which probably inhibited maturation of companion worms, and it is postulated that once this female vacates, there is a sequential maturation and spawning of subordinate worms. The greatest number of mature worms, and the largest worms, occurred during October and November, but because of the extended larval settlement period it is a matter of debate whether the worm is an annual, or has a more extended lifetime. Iphitime paguri was found occupying the apical whorl of4.6% of Buccinum undatum shells and 2.6% of Neptunea antiqua shells occupied by the hermit crab Eupagurus bernhardus. The worm is very fragile and, being rare, there is insufficient data to define its biology. The longest worm was 50 mm (alcohol- preserved length) and the largest jaw length 760 μm; there appeared to be an inverse relationship between length of worm and jaw size, and no worm over 25 mm had jaws larger than 250 μm. All ovigerous worms had small jaws. Nereis fucata was found in 2.6% of Neptunea antiqua and 7.1% of Buccinum undatum shells occupied by the hermit crab. It was not found associated with Iphitime paguri.

The toxin tetramine from the “edible” whelk Neptunea antiqua

U. Anthoni, L. Bohlin, C. Larsen, P. Nielsen, N. H. Nielsen and C. Christophersen. The toxin tetramine from the “edible” whelk Neptunea antiqua. Toxicon 27, 717–723, 1989.—The chemical nature of extracts of the marine gastropod Neptunea antiqua collected in the North Sea has been investigated. Amino acid analysis and spectroscopical studies (FAB MS, 1H NMR, 13C NMR and IR) on fractions purified by Biogel P-2 and Amberlite IR 120 column chromatography allowed the identification of 19 components. It was established that the water-soluble toxin responsible for poisonings, following ingestion of this snail, is tetramine (the tetramethylammonium ion present as an unknown salt). Contrary to what occurs in other Neptunea species ( N. arthritica and N. intersculpta), tetramine was found not only in the salivary gland, but also in the remaining part of the animal, albeit in smaller concentration. In the isolated guinea-pig ileum assay, synergistic effects with other main components present (betaine, homarine) could not be demonstrated. Choline esters, believed to act synergistically in other Neptunea species, were not detected in Neptunea antiqua.

Food poisoning due to the consumption of red whelks (Neptunea antiqua).

Two incidents of toxin-type food poisoning in N.E. Scotland associated with the consumption of red whelks (Neptunea antiqua) are described. Four patients developed symptoms within 1 h of consuming whole whelks. These included visual disturbances--double vision and difficulty in focusing--tingling of the fingers, prostration and in one subject nausea, vomiting, diarrhoea and ataxia. In all cases recovery was complete in 24 h. Using a newly developed analytical technique the concentration of the causative toxin, tetramine, in the salivary glands of the whelks consumed was estimated at 0.07%, equivalent to a content of 3.75 mg/100 g of the shellfish.

On the morphology and life-history ofPodocotyle Reflexa(Creplin, 1825) Odhner, 1905, and a Comparison of its developmental stages with those ofP. Atomon(Rudolphi, 1802) Odhner, 1905 (Trematoda, Opecoelidae)

Abstract The life-cycle of the digenetic trematode Podocotyle reflexa (Creplin, 1825) Odhner, 1905 (fam. Opecoelidae) is shown experimentally. The cotylomicrocercous cercaria of P. reflexa, C. buccini Lebour, 1911, develops in sporocysts in Buccinum undatum L. and Neptunea antiqua (L.) (Gastropoda, Prosobranchia). The cercariae encyst in muscles of various crustaceans. Crangon crangon (L.) was used as experimental intermediate host. The metacercariae developed into P. reflexa in cod, Gadus morhua L. given shrimps with two to four months old metacercariae. The cercaria, metacercaria and adult of P. reflexa are redescribed and compared with similar developmental stages of P. atomon (Rudolphi, 1802) Odhner, 1905. P. reflexa has been considered a synonym of P. atomon. The tegument and suckers of the cercaria of P. reflexa were studied in the transmission electron microscope. All developmental stages of P. reflexa and P. atomon were studied in the stereoscan electron microscope. The surface of the cercaria of P. reflexa is smooth apart from a microvillous fringe which surrounds the suckers, whereas the whole surface of the cercaria of P. atomon is covered with microvilli. The microvilli of both cercarial species are shed a few hours after penetration into the crustacean host. A few days after encystment the metacercariae of both species develop short microvillus-like projections all over the body. These projections disappear about one month after encystment, and the metacercariae do not grow further.

Immunochemical properties of the haemocyanins from Buccinum undatum (L.) and Neptunea antiqua (L.)

1. 1. Rabbit antiserum to Buccinum undatum haemocyanin cross-reacted with Neptunea antiqua haemocyanin and vice versa, the reaction in each case being one of partial identity. Antiserum to B. undatum haemocyanin also cross-reacted weakly with Colus graeilis haemocyanin, and very weakly with Murex trunculus haemocyanin. 2. 2. Depending upon the pH and the Ca 2+ or Mg 2+ concentrations, the reaction of the haemocyanins with their rabbit antisera resulted in the formation of single or multiple precipitin lines in agar and different equivalence points in the quantitative precipitin assay. 3. 3. Analytical ultracentrifugation and electrophoretic analysis showed that this phenomenon was caused by pH-induced dissociation of the haemocyanins, both whole molecules and their dissociation products being capable of reacting with antisera. 4. 4. An interpretation of the patterns observed in immunoelectrophoresis is given based on the time taken for haemocyanin molecules to dissociate at certain pH values, and the electrophoretic mobilities and diffusion coefficients of the dissociation products.