Sheila Tilmouth - Fen Raft Spider Residency

Sheila Tilmouth's artist residency with the Fen Raft Spider 2009

This beautiful, semi-aquatic fish eating spider was discovered in 1956 at Redgrave and Lopham Fen near Diss on the borders of Norfolk and Suffolk at the source of the River Waveney. It lives in the margins of pools originally dug for peat and is dependent on the saw sedge found there.

Over subsequent decades survival of this species has been threatened through degradation of its wetland habitat due to water extraction and pig and poultry farm pollution. A species recovery program was initiated in 1991 by Natural England and systematic monitoring and habitat management has since been established overseen by Dr Helen Smith. More information can be obtained from its dedicated website www.dolomedes.org.uk

Arts Council England awarded a grant to work alongside this conservation project. The residency is also supported by Suffolk Wildlife Trust and the BBC Wildlife Fund. Local groups and schoolchildren will engage with printmaking workshops at Redgrave and Lopham Fen and Carlton Marsh Education Centre. An exhibition of work will be mounted at each venue.

I am also working with The Natural History Museum, Buglife, The British Arachnological Society and Little Ouse Headwaters Project.

Relics A spiderling sheds its skin up to 15 times as it grows to adulthood. Each cast is a perfect ghost of the body that inhabited it.

Moult A spider moult is a complicated procedure with eight legs to negotiate. The spider hangs in suspension as they release themselves in a beautifully choreographed motion.

The Bottleneck Severe decline of a species results in a diminished gene pool that cannot recover even if numbers increase. This leaves the population vulnerable as it has less ability to adapt or have resistance to changing environmental conditions.

Genetic Codes The striking banding is found on 75% of this spider population with 25% remaining unbanded. It is determined by two inherited genes - one from each parent. The unbanded gene is recessive.

Hairy spider: etching This ventral view of the spider shows its complicated anatomy of joints and legs. The swollen tip of the palps indicates that this is a male and it is here that seminal fluid is stored. The tip is inserted into the female during copulation.

Nursery web: collagraph Much of the life of the spider is played out on the water margins of deep pools historically dug for peat - they only climb the tall sedges to provide a nursery web for their spiderlings. From here the young spiders disperse to begin independent life.

Heritage: collagraph The underlying bed of chalk at Redgrave and Lopham determines the neutral or alkali pH of the water that feeds the fen, thereby creating a particular habitat suitable for the fen raft spider. The Cretaceous period during which the chalk was deposited was long after the first creatures resembling arachnids evolved.

Small wetland creatures: linocut The fen supports a richly diverse abundance of small creatures which make up a complex food chain. A species can be predator or victim at different stages of development so that a spider will eat a tadpole but in turn be dinner for a frog.

Hunting: photo The spider hunts with its back legs resting on vegetation and front legs on the water surface to pick up vibrations from movements of its prey. It moves at speed catching the victim in its jaws whilst manipulating it with the help of its legs and paralyzing it with venom injected through fangs.

The catch: tinted lino cut After the catch has been paralysed it is infused with digestive juices that allow the spider to ingest its prey as liquid. The many hairs and comb like structures in and around its mouthparts ensure that solid particles are separated out and not ingested by the spider.

Courtship: digital image The spiders are ready to mate when they become adult in their third summer. Attracted by pheromones, receptivity is communicated through vibrations on the water surface. Fertilization takes place through insertion of the elaborate structures within the male palp into the female's epigyne.

Female with egg sac: wood engraving The female carries the egg sac around with her for two to three weeks, holding it against her body with her chelicera and palps. It must be kept moist so she stays near the waters edge, frequently dipping it into the pool.

Building the egg sac: photo When the female is ready to lay her eggs she builds a silken cup going deep into the clumps of sedge which she uses for support. Because of this the activity is rarely seen. She seals its opening with more silk after laying the eggs inside then cuts it free it from the sedge supports.

Saw sedge: collagraph At Redgrave and Lopham Fen these sedges are essential elements in the spider's habitat providing support for nursery webs and egg sac construction. The clumps of stiff leaves provide an open and sunny structure for the spiders activities.

Spiderlings: photo When the eggs are ready to hatch the female constructs a web above the water level in the sedge. Breaking free of the sac the spiderlings cluster together within the web under the guard of their mother.

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Printing Techniques

I visited the fen for a few days every month during the Fen Raft Spider's active period from May until October collecting as much visual information as the weather would permit working alongside Dr Helen Smith. Early stages of the residency were spent in the studio experimenting with a variety of print techniques in readiness for more worked images later and I started piecing together the hugely complicated anatomy of arachnids.

Etching on zinc using copper sulphate and salt mordant. A spider has four pairs of hairy legs with spines which are made up of several articulated segments with claws on the tip. They are used for movement, capturing prey and defence and are important for grooming. They have a sensory ability for touch and taste. They also sense air movements and water vibrations.

Collagraph using PVA and carborundum grit experimenting with the technique to explore its potential to create a tonal, textural image. When inking up the plate grit holds ink whilst it can be wiped off the smoother surface of PVA. There is a tactile quality to the image suggesting weathered surfaces.

Linocut allows a dramatic use of black and white in the design of an image. This study illustrates the extraordinary ability of this spider to catch aquatic prey, often larger than itself. Fine marks depict the down covering all of the spider's body. This cocoons the spider in a layer of air as it dives underwater providing an effective water resistant layer.

Wood engraving. The precise marks made in this method of printmaking allow a methodical, analytic drawing of the spider's jaws and palps. At the bottom of the jaws the fangs are visible which are used for injecting venom into prey.

Etching on copper using ferric chloride and citric mordant. There are two sections to the body of the spider, the cephalothorax, which includes the head, and abdomen. The image illustrates the characteristic banding on its body giving effective camouflage when the spider rests amongst the water margins of pools mimicking reflections around the plant growth.

Collagraph using PVA, grasses, string, and carborundum grit building a relief image on card. The varied textures on the plate allow use of layers of colour applied with wiping and surface rolling. This creates an impression of a blurred underwater world with shadowy colours and forms of weeds and algae.