Jim Logan, Gatehouse-of-Fleet
Jim Logan, marine biologist, returned to the Baptist Church Centre to present his lecture on the seashells found on the coast of Dumfries and Galloway.
We are in the fortunate position of having a coastline with a variety of habitats from rocky areas, mudflats, shingle beaches and sand with areas of low to high salinity. This produces the conditions which allow an extraordinary variety of seashell species. The speaker and his wife have found up to a hundred-and-ten species with the average count per beach of twenty to thirty species which, compared to the Ayrshire coast with only thirty species overall, gives an idea of the rich diversity.
The shells can be split into two groups, the Gastropods and the Bivalves.
The Gastropods are the snail like seashells characterised by a large foot. Of these there are four species of winkle occupying different tidal areas. Limpets who are herbivorous algae eaters always returning to the same starting location. Carnivorous shells, the Dog Whelk and the Necklace shell, both drilling holes into other shell species. The unicorn horn shaped Tower shell, popular with children, the Pelican foot shell, Common and Red Whelks. Mud snails abound in great numbers and are the main source of food for the Shelduck often seen on the Solway mudflats.
The second group are the bivalves which are hinged shells as in in cockles or scallops. Other than Scallops, Mussels and Oysters, the bivalves typically bury themselves into the mud or sand and use an inhalant siphon to feed on plankton. These are a source of food for the specialist seabirds such as the oyster catcher. The razor clam is a good example of this, with a large muscular foot to anchor itself into the mud or sand. Mussels however do not bury themselves but attach themselves to rocks etc, using a fine thread-like material. Scallops swim by ejecting water in a jet often as a defence from starfish.
Stone- and wood-boring shells were also described along with the boat owner's enemy ,the Barnacle.
The lecture concluded with rarities such as the Tortoiseshell Limpet, Keyhole Limpet, Elephant tusk shell and the Canoe shell found in Luce Bay.
The lecturer showed an extraordinary depth of knowledge and enthusiasm and the audience showed their appreciation of this excellent and comprehensive lecture.
A.G.