Grey sea slugs
At this time of year grey sea slugs come onto the seashore and into rockpools to breed. Look for pairs of grey sea slugs with their white egg masses under seashore rocks at low tide. Their dull-sounding name doesn’t do them justice as their colour can vary from almost white or grey to reddish brown, with a covering of soft finger-like projections. They can grow up to 12cm long and have a distinctive V shaped mark on their head. Their egg ribbons are twisted together to form a white patch on the underside of rocks and typically contain more than 400,000 eggs. They are a specialised feeder living almost exclusively on sea anemones, processing the stinging cells of their prey and using them as their own defence against predators.
Purple laver is a common winter seaweed usually found growing on rocks on the upper part of the intertidal zone. It is purplish-brown in colour and has extremely thin, almost translucent fronds, which vary in shape and size depending on the species. The form that you see on the rocks is just one phase of its life cycle, prior to this it would have gone through a microscopic phase called conchocelis during which it lives in small shells on the seabed. When wet purple laver is extremely slippery to the touch and can be a hazard to walk on, but when dried out it forms a papery layer over the rock. In spring the warmer temperatures and longer periods of sunlight burn this seaweed and it disappears until next winter.
Laver is edible and used in the traditional Welsh dish of laverbread. It is also a common ingredient in Japanese cuisine, as a wrap for sushi or a garnish, and is referred to as nori.
Flat Periwinkle eggs
Flat periwinkles are common on all shores where brown seaweeds are found, usually in the mid to lower tidal levels on rocky shores. They can vary in colour from olive green or yellow to brown or even patterned. This is the time of year when they lay their eggs in a gelatinous, whitish, oval shaped mass on seaweeds such as bladder wrack and toothed wrack. After 4 weeks the eggs hatch and the crawling young are able to start feeding immediately on the seaweed.
Let us know what you find
Let us know what marine life you see by posting it on our Facebook page or letting us know on Twitter! We'd love to see any photos you take.
Grey seaslug eggs © Helen Earwicker
Purple laver © Julie Hatcher
Flat Periwinkle eggs © PeterTinsley