Annual Address

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This years Palaeontological Association AGM & Annual Address is next Wednesday 
(12 March 1997) and will be held in the Flett Lecture Theatre, Natural History 
Museum, London. All are welcome at both the AGM and Annual Address.

The AGM will commence at 2.30 pm and will be followed immediately by the Annual 
Address (see abstract below). At approximately 4 pm there will be a wine 
reception.

This years address will be:

Hydrothermal vent communities: from the origin of life to present day diversity

            Prof. J. R. Cann FRS, University of Leeds
                                 ABSTRACT

It is less than 20 years since the exotic communities of animals living around 
the hydrothermal vents of the mid-ocean ridges were first discovered, but already 
they have taken an important place in the understanding of ecological systems. In 
these tiny oases of life, only a few hundred metres across, productivity is as 
high as in a tropical rain forest, though diversity at any single site is low. 
Life here is fuelled by microbial chemosynthesis: microbes may be free living or 
have symbiotic relationships with worms, snails, clams or mussels. Many of the 
microbes are hyperthermophile, and resistant to sulphide and metal toxicity. The 
same is true of many of the animals; very few of the organisms of the surrounding 
ocean floor venture into the vent environment. The vent ecosystems raise some 
fascinating problems, most of which still await an answer. How do vent organisms 
manage the dual strategy of staying with the vent while it is still alive, but 
colonise new vent fields as soon as they form? Why do the faunal assemblages at 
vents vary so much from place to place, when the vent environment is so similar 
around the world? Where do the vent organisms come from? What do ancient vent 
communities look like? What is the role of the faint light emitted by the vent 
waters? Can it sustain photosynthesis in the dark in abyssal depths? Did 
photosynthesis originate at hydrothermal vents? Did, indeed, life originate 
there?



Dr Mark A. Purnell

Department of Geology, University of Leicester
University Road, Leicester LE1 7RH, U.K
tel: +44 116 2523645  fax: +44 116 2523918
http://www.le.ac.uk/geology/staff/map2.html