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.
SOURCE: http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/5217558.stm
Ancient
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’
clade
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’
for gastropods
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.
Snail’s
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
floating cages
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
in Mexico
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
vent
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
lagoon
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
in Britain
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.
SOURCE: http://news.bbc.co.uk/1/hi/health/5165124.stm
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
Indrella amputta. © The Natural History Museum, London.
Mariaella dussumieri. © The Natural History Museum, London.
Beddomea trifasciatus (lowland form). © The Natural History Museum, London.