At the beginning of June an Ocean Sunfish, Mola mola, was spotted from a boat near Kimmeridge Bay. This was not totally unexpected as this species is a plankton feeder and is often associated with jellyfish which have been around in large numbers since early May. The first sign of a sunfish is usually splashing as the animal flaps its large dorsal fin at the surface of the water. Although these fish can tip the scales at a whopping 2 tonnes and produce the most eggs of any fish in the world (estimated at up to 300 million eggs at a time) the ones spotted in Dorset during the summer months are usually relatively small and described as ‘dustbin lid sized’.
Also at the beginning of June a solitary grey seal visited Kimmeridge Bay and was seen almost every day for a week feeding and bottling (relaxing in a vertical position with nose out of the water) in the sea. At the same time a dead seal carcass washed ashore causing concern that the visiting seal had died. However another sighting of the live seal in Worbarrow Bay confirmed that this was not the case. A third sighting of a grey seal was reported at Portland Bill early in July.
In July there was an unconfirmed report of a common seal pup in Poole Harbour. Common seals give birth in the summer and their pups usually start swimming within 24 hours of being born. This is unlike grey seals which give birth in the winter months to white-coated pups that normally stay on land for the first 4 weeks or so during which time they moult their white coat. It is thought that the white coats are a throw back to the last ice-age when the white coats would have camouflaged them in the snow from predators. Common seal pups have a white coat as they develop inside their mother but this is usually lost in the womb.
Dorset Wildlife Trust is currently trying to get a clearer picture of the number of seals of both species resident or semi-resident in Dorset waters. Please send any sightings with the date and location and if possible, a photograph, to
Barrel jellyfish, Rhizostoma pulmo, have continued to arrive along the Dorset coast in large numbers with specimens washing ashore at Studland and even on Brownsea Island in Poole Harbour. In early July another type of jellyfish appeared off Chesil Beach, the Compass Jellyfish, Chrysaora hysoscella. This is smaller than the barrel jellyfish, typically up to 30cm in diameter but often smaller, with brown v-shaped markings resembling the points of a compass hence the name. Unlike the barrel jellyfish this has long, fine tentacles which give a potent sting. This species is often seen here in small numbers in the summer months sometimes associated with another similar-sized stinger, the blue jellyfish, Cyanea lamarckii. The blue jellyfish is currently being seen along the Cornish coast and may well appear in Dorset over the summer, so is also one to look out for.
It is important to record jellyfish spotted either washed ashore or in the water to create a better understanding of their distribution and the environmental factors that influence this. They are a staple food of one our marine giants, the leatherback turtle which travels from its breeding area in the Caribbean to feed on jellyfish in our waters.
Baby shore crabs
Visitors to the beach at Kimmeridge over the last month have noticed large numbers of tiny but very active crabs underfoot at low tide. These are the juvenile shore crabs, Carcinus maenas, that have spent the last few weeks drifting in the sea as planktonic larvae. Having settled on the shore they now feed and grow rapidly, taking advantage of the plentiful food supply at this time of year, moulting their shells regularly as they grow. In August they are particularly noticeable because of their large numbers, openly crawling around on the beach at low tide and making it difficult to avoid treading on them. Their shells are more colourfully decorated than those of adult shore crabs in order for them to blend in with the tiny stones and broken shells of the beach and they are about the size of a raisin.
Sunfish © Julie Hatcher
Grey Seal © Julie Hatcher
Blue & Compass Jellyfish © Carol Elliott
Shore Crab Eggs © Julie Hatcher