AVERAGE CALORIES IN A DAY

Best viewed very small - not the best quality now the video format's converted. Lampreys mating and nest building! 11th March 2011 - a brook beside the River Itchen at St Cross, just south of Winchester, Hampshire.

In the first few seconds look for the couple at the top mating. Then watch the one that leaves the group to bring back a stone to the nest. A second stone is brought before the clip ends. And look in rivers and streams for your own lampreys about now - it's an amazing sight if you catch them!

A profound joy to see these wonderful creatures. Five European Brook Lampreys - Lampetra planeri. They have a fascinating life cycle. The blind hatchlings float down stream and embed themselves in burrows in silt where they spend about three to seven years maturing, filtering detritus for food. When ready, they metamorphose into sighted adults and emerge from their burrows. This happens in the autumn. From then till early spring they live a secretive life, swimming upstream by night and hiding under stones by day. Once they've reached a suitable gravel spawning ground, in small groups they build a nest - a shallow depression in the stream bed. They build the nest by moving stones, lifting them with their round sucker-like mouths. They are able to move stones twice their body weight. Spawning happens in daylight in March or April, once the water temperature reaches about 10C. The females attach themselves to stones with their suckers and the males squirm vigorously, releasing sperm. The eggs are attached to stones in the nest, hatching within the month. Each female lays about 1,500 eggs. After spawning the lampreys die. Adult Brook Lampreys are unable to feed so they gradually loose weight during their journey upstream.

I sat entranced and watched eggs being fertilised and lampreys carefully moving small stones into the nesting pool and rearranging them. Two days later there wasn't a sign of the creatures, though the nest they'd made was still visible if you knew what to look for. A little stripy predatory fish was at the spot.

A profound joy to see these wonderful creatures. Five European Brook Lampreys - Lampetra planeri. They have a fascinating life cycle. The blind hatchlings float down stream and embed themselves in burrows in silt where they spend about three to seven years maturing, filtering organic material for food. When ready, they metamorphose into sighted adults and emerge from their burrows. This happens in the autumn. From then till early spring they live a secretive life, swimming upstream by night and hiding under stones by day. Once they've reached a suitable gravel spawning ground, in small groups they build a nest - a shallow depression in the stream bed. They build the nest by moving stones, lifting them with their round sucker-like mouths. They are able to move stones twice their body weight. Spawning happens in daylight in March or April, once the water temperature reaches about 10C. The females attach themselves to stones with their suckers and the males squirm vigorously, releasing sperm. Females release their eggs in a cloud which attach to stones in the nest, hatching within the month. Each female lays about 1,500 eggs. After spawning the lampreys die. Adult Brook Lampreys are unable to feed so they gradually loose weight during their journey upstream.

I sat entranced and watched eggs being fertilised and lampreys carefully moving small stones into the nesting pool and rearranging them. Two days later there wasn't a sign of the creatures, though the nest they'd made was still visible if you knew what to look for. The little stripy predatory fish I’d seen at the start was back at the spot.