Marine wildlife to look for in June

Magic seaweed Cystoseira tamariscifolia P Tinsley  

Above: Magic seaweed © Paul Tinsley
Below: Cuttlefish eggs © Julie Hatcher, Corkwing wrasse with nest © Chris Roberts

Early summer is a busy time for nest building and egg laying in the shallow waters along the coast. It is also when seaweeds are at their most colourful. Here are a few things to look out for this month.

Magic seaweed

Magic seaweed is so-named for its trick of changing colour whether in or out of water. Washed up specimens look like any bushy brown seaweed but if you drop it back into the sea it instantly turns blue or purple to look like it does on the seabed. If snorkelling or kayaking in shallow water this large seaweed stands out from the rest as the only blue one, although as the summer sun gets stronger it will gradually grow paler as the colour is bleached out of it. Look for small broken-off pieces at the water’s edge or for small plants in low shore rockpools.


Late spring and early summer is when colour-changing cuttlefish gather inshore to breed. A bit of rough weather at this time can dislodge their ‘sea-grape’ eggs from the seabed anchor to which they have been attached. The result can be bunches of these black eggs washing up on the shore out of water. Each grape-sized egg contains a single developing embryo along with some of the mother’s black ink (sepia) to hide it from would-be predators. At our Fine Foundation Marine Centre in Kimmeridge Bay we have often been able to rescue stranded eggs from drying out by putting them in our aquarium and have successfully hatched baby cuttlefish over a number of years.

Sea-grapes © J Hatcher

Sea-grapes © J Hatcher

Corkwing wrasse nests

May and early June are when male corkwing wrasse, a common shallow water fish, build their seaweed nests and entice females to lay their eggs. They take great care to build and decorate these untidy mounds by picking pieces of seaweed and stuffing them into cracks and crevices between rocks. They chose particular types and colours of seaweed to show off their abilities in the hope of attracting one or several females. Once the eggs are laid and fertilised the male remains close by, maintaining the nest and fanning it with his fins, protecting the developing eggs from potential predators. Diving and snorkelling are the best ways to see these activities first hand although they can sometimes be seen from the shore alongside rocky ledges at low tide.

Corkwing wrasse © C Roberts

Corkwing wrasse © C Roberts


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