World Congress of Malacology Antwerp ... - Unitas Malacologica

New techniques yield new insights on the basic biology of living Microgastropods
Hickman, Carole S.
Department of Integrative Biology, University of California, 3060 VLSB, Berkeley, CA 94720-3140,
California, USA,
Email: caroleh@berkeley.edu
The microgastropod grade of evolution is rich in ecological and taxonomic diversity and full of
unusual and unexpected biological phenomena. Little is known of the basic biology of most
microgastropod taxa, including entire clades that are known only from shells. The challenge of
closing the knowledge gap at the level of the living animal should have special appeal to those who
are attracted to field research and recognition of novel phenomena. Advantages of microgastropods in
comparative research include uniformity of size (attention to scaling is not required), life history
properties conducive to rapid turnover and high evolutionary potential, and the availability of
exemplar taxa across the phylogenetic diversity of Gastropoda. Microgastropod species that feed on
microbial films may attain extraordinary population sizes for quantitative investigations, particularly
those involving phenotypic and genetic variation and polymorphism. Microgastropod groups adapted
to novel substrates in the deep sea and for life in extreme environments are attractive models for
research in exobiology and paleobiological investigation of patterns of biosphere recovery following
global crises and mass extinctions.
Chances of success in pursuit of the living microgastropod can be increased both by looking in
unsuspected places and by using new sampling and concentrating techniques. Examples of new
methods include: (1) the use of light traps and emergence traps and (2) investigation of novel animalsubstrate
interactions. Examples of new discoveries using these approaches include: (1) swimming,
aggregation, and mass spawning of scissurellid gastropods at light traps, (2) diel vertical migration of
microgastropods living on marine algae and seagrasses, (3) epipsammic browsing by species in three
distinct microgastropod clades, and (4) mucous thread “kiting” and upside-down locomotion in
surface tension.
Molluscan models for cardiac physiology
Hill, Robert B. 1 ; Kuwasawa, Kiyoaki 2 ; Sun, Ying 3
1. Department of Biological Sciences, University of Rhode Island, Kingston RI 02881, USA,
Email: BOB@uri.edu
2. Neurobiology Laboratory, Faculty of Science, Okayama University of Science, Ridai-cho 1-1,
Okayama-shi, Okayama 700-0005, Japan,
Email:kuwasawa@das.ous.ac.jp
3. Department of Electrical and Computer Engineering, University of Rhode Island, Kingston RI
02881, USA,
Email: Sun@ele.uri.edu
Advances in cardiac physiology have proceeded in parallel in Mollusca and Vertebrata. The Law of
the Heart was formulated for the human heart by Starling in 1897, and for the heart of Aplysia
fasciata by Straub in 1904. The literature of cardiac mechanics is vast by now, but one may point out
that it was advanced by studies on Busycon canaliculatum by Smith in 1985. Spike and plateau
electrograms from molluscan hearts have been studied at least since the work of Rijlant in 1931. The
relationship between force and the time course of the molluscan cardiac action potential has
repeatedly been directed towards interpretation of modulation of cardiac function by bioactive
substances. In several cases, it appears that the molluscan cardiac action potential has a calcium spike
and a plateau phase consisting of sodium current under calcium control. This may be simulated as a
computer model. Since 1967 Aplysia and Dolabella have been used for studies of neural control of
cardiac muscle. The action of neurally released acetylcholine, from inhibitory cardiac innervation,
was first shown to be mediated by induction of unitary IJPs in molluscan tissue. The bivalve
Mercenaria mercenaria is an appropriate subject for the study of cardiac innervation.
97