|Unitas Student Research Awards||Octopus culture – juvenile growth in floating cages|
|Concern for Newbury bypass snail||Sustainable dye harvest from purple conch in Mexico|
|Ancient shell beads: seeing a world in a grain of sand||Snail in hob-nail boots from hydrothermal vent|
|Bivalved Methuselah recorded climate for 374 years||Intersex in estuarine clams: endocrine disruption ?|
|Burgess shale Odontogriphus was a soft-bodied mollusc||Magnetically responsive neurons of Tritonia|
|Monoplacophorans and chitons form a ‘Serialia’ clade||Ruditapes philippinarum in Venice lagoon|
|Review of hermaphroditism||Conus magus venom painkiller launched in Britain|
|Snail’s love dart delivers mucus to increase paternity||Cosmetic from snail slime|
|Crab scars reveal survival advantage of left-handed snails|
Unitas Student Research Awards
Student members of Unitas Malacologica may apply for two awards of up to 1000 Euros . Membership is €16 per year, and an application form is at www.ucd.ie/zoology/unitas
The next congress will be 15-20 July 2007 in Antwerp.
Concern for Newbury bypass snail
Vertigo moulinsiana, a rare 1.5 mm snail that inhabits deep swamp litter, almost halted building of the Newbury by-pass in 1996, until they were relocated. Now, wildlife group Buglife report that the relocated populations are extinct, because the pipe feeding water to the translocation site became silted up. English Nature said there had been problems with vandalism and low water levels, but there had been massive declines in other populations on protected sites, and the snail is a ‘boom-and-bust’ species. Studies undertaken during construction of the by-pass revealed that the species was present in many previously undiscovered sites.
shell beads: seeing a world in a grain of sand
Two pierced shells of Nassarius gibbulosus from Israel and one from Algeria, in collections in the Natural History Museum, London, and Musée de l’Homme, Paris, have been dated to 100,000 - 135,000 y ago. Dating relied on comparison of sediment adherent to one shell with sediment samples from a layer bearing dated human fossils. The previous record of 41 perforated Nassarius kraussianus from a cave in South Africa was dated by optically stimulated luminescence and thermoluminescence to 75,000 y ago. Archaeologists relate the use of jewellery to the start of symbolism, the expression of modern cognitive abilities and acquisition of articulate language, and this discovery puts those abilities much earlier than previously thought.
SOURCE: Vanhaeren M et al. 2006. Science, 312, 1785-8
Jewellery and the Birth of Language
“Ug’s wife gets pearls. What do you bring me? Shells! …”
Bivalved Methuselah recorded climate for 374 years
Shells of bivalves are increasingly used for climate reconstruction, recording changes in temperature, food, salinity and pollution. These are recorded in the shells as variables such as growth rate and oxygen isotope data, d18O (which is controlled by 18O/16O ratio in seawater and ambient temperature). A specimen of Arctica islandica collected alive near Iceland in 1868 was examined and found to have been 374 y old when taken. This is the oldest ever reported individual animal. Its shell recorded the volcanic eruption of Mt Tambora in 1815, the highly variable growth at the peak of the Little Ice Age around 1550-1620 and mild climate near its end around 1765-80.
SOURCE: Schone B.R. et al. 2005. Palaeogeography, Palaeoclimatology, Palaeoecology 228, 130-148.
Burgess shale Odontogriphus was
a soft-bodied mollusc
A smudge on a piece of shale, a toothed riddle, for years regarded as probably a Cambrian lophophorate. Now new material has shown that the ‘lophophore’ was probably one or more pairs of radular tooth rows. The animal may have been related to Wiwaxia, a scaly lophotrochozoan, and also to the even older late Precambrian Kimberella, which left no trace of a radula, but is associated with sweeping marks on microbial mats similar to the grazing marks of modern gastropods.
SOURCE: Caron J-B et al. Nature 442, 159-163.
Monoplacophorans and chitons form a ‘Serialia’
A 1.2 kb fragment of 28S rRNA from a small monoplacophoran from the Weddell Sea, has been analysed with material from other molluscs and outgroups. The analysis shows that Mollusca and the classes Caudofoveata, Solenogastres, Scaphopoda and Cephalopoda are monophyletic, The gastropoda are diphyletic (patellogastropods separated from other gastropods and heteroconchs separated from other bivalvia). There was strong support for a clade containing Monoplacophora and Polycladophora. The clade, named Serialia by the authors, contains two classes whose members have serially repeated gills and 8 sets of pedal retractor muscles.
SOURCE: Giribet G et al. 2006. Proc Nat Acad. Sci USA. 103, 7723-8.
Review of hermaphroditism
The journal Integrative and Comparative Biology, formerly the American Zoologist, devotes much of its August 2006 issue (Vol 46, No 4) to sexual selection and mating systems in hermaphodites, including on pp 419-429, ‘Tales of two snails’ (Lymnaea and Helix) by Joris Koene.
Torsion was not ‘one giant leap’
Louis Page reviews the traditional ‘rotation hypothesis’ of gastropod torsion and argues that recent studies of development do not show the supposed synchronous rotation of all components of the visceral hump on the head-foot. Instead, there is a conserved state of asymmetry in which the mantle cavity originates from one side only of a bilateral set of cavities. The attractive features of this ‘asymmetry hypothesis’ are that it does not require a macromutation nor an ancestor with its shell coiled over its head.
SOURCE: Page LR. 2006. Integr. & Comp. Biol. 46, 134-143.
love dart delivers mucus to increase paternity
Dart shooting is a bizarre component of helicid snail courtship. It doesn’t affect the likelihood that copulation will ensue, nor the size of the sperm donation. However it does increase the number of sperm stored by the recipient and increases paternity relative to unsuccessful dart shooters. Now Chase and Blanchard show that the dart exerts its effect by transferring mucus from a gland associated with the dart sac. This mucus induces contraction of radial muscles at the junction of the bursal tract and diverticulum. This reduces the digestion of sperm (which averages 99.98%). Dart shooting may have evolved as a result of sperm competition, although cryptic female choice is possible.
SOURCE: Chase R. and Blanchard K.C. Proc R Soc B (2006) 273, 1471-1475.
Calcareous dart fired by the lower snail is visible below breathing
pore of partner.
Sometimes the dart penetrates completely.
Crab scars reveal survival advantage
of left-handed snails
Most marine snails’ shells coil dextrally, but some rare species were sinistral. Left-handed whelks and cones arose in the Pliocene, 3.5-4 mya. The fossil record on otherwise similar dextral and sinistral species shows, rather surprisingly, that, far from being selectively neutral after hatching, rare sinistral shells had fewer repairs to crab predation attempts. Sinistrality provides a competitive edge because the asymmetric claw that the crab uses to peel the snail’s shell is typically on their right hand side.
SOURCE: Dietl G.P. and Hendricks J.R. 2006. Biol. Lett. Doi 10.1098/rsbl.2006.0465
Octopus culture – juvenile growth in
Interest in diversifying the number of farmable marine species has resulted in studies of octopus culture . In rectangular floating cages containing PVC tubes as refugia, there was no significant cannibalism. Good growth and low mortality was achieved from an initial density of 11.9 kg per m3.
SOURCE: Rodriguez C. 2006. Aquaculture 254, 293-300.
Sustainable dye harvest from purple conch
The purple conch Plicopurpura pansa when disturbed exudes a secretion that photo-oxidises to an intense purple hue. This secretion is used for dying ceremonial dresses, and can be extracted repetitively by ‘milking’. 310 litres of dye can be harvested along 50 km of shore in a 3 month season.
SOURCE: Chavez EA & Michel-Morfin JE. 2006. Amer. Malacol. Bull. 21, 51-57.
Snail in hob-nail boots from hydrothermal
The as-yet unnamed ‘scaly foot’ snails from deep sea vents cover the dorsal surface of the foot with hard black sclerites of iron sulphides, pyrite (FeS2) and greigite (Fe3S4). The crystals are not aligned for magnetic sensing. They seem to be sequestered from the toxic sulphides emitted by the black smokers, and may have evolved as protection against crabs.
SOURCE: Suzuki Y et al. 2006. Earth and Planetary Science Letters 242, 39-50.
Intersex in estuarine clams: endocrine disruption
21% of male Scobicularia plana from the Avon Estuary in SW Britain show intersex (oocytes in testes). Females are not affected. Clams from sites in other estuaries do not display intersex, so it is possible that (xeno)oestrogens, possibly from a sewage treatment work, are responsible. Endocrine disruption (ED) of male fish has been linked to ED chemicals thought to mimic the action of the female sex hormone 17-b-oestradiol.
SOURCE: Chesman BS and Langston WJ. 2006. Biol. Lett. Doi 10.1098/rsbl.2006.0482
Magnetically responsive neurons of Tritonia
Diverse animals use the Earth’s magnetic field (EMF) as orientation cues, but the sea slug Tritonia is one of only a handful of animals in which nerve impulses have been recorded. Three pairs of pedal ganglion neurons respond to changes in the EMF. Neurites from Pd5 innervate the foot and body wall and probably regulate ciliary beating involved in crawling by release of neuropeptides directly on target cells.
SOURCE: Cain SD et al. 2006. J. Comp. Physiol. A. 192, 235-245.
Ruditapes philippinarum in Venice
The Manila clam, deliberately introduced to the Venice lagoon in 1983, has been the most successful of 19 invertebrate introductions. There has been a sharp reduction in other filter feeding bivalves, and filtration capacity has more than doubled. The Manila clam extracts more biomass than primary production can provide, the excess being provided by organic substrates stirred up by clam dredging.
SOURCE: Pranovi F et al. 2006. Biological Invasions, 8, 595-609.
Conus magus venom painkiller launched
Prialt is a synthetic version of a toxin from the magician’s cone snail first isolated at the University of Utah. Manufactured in Japan, approved for use in USA in 2004 and in the EU in 2005, it is the first injected non-opioid painkiller to be used in Europe. It is designed for patients suffering chronic pain for whom morphine is ineffective or unsuitable.
Cosmetic from snail slime
Chilean firm Cosmeticas Elicina uses surplus production from a snail farming industry to extract 35,000 40 g units of snail slime each month as a cosmetic cream containing collagen, elastin and glycolic acid that helps generate new skin cells.
SOURCE: www.ft.com/global village