Species Focus - Jellyfish

Way down on the evolutionary tree, Jellyfish, let’s call them jellies, have been around and relatively unchanged for millennia. Famously mostly water, with a very basic neurology, they have the capacity to sting to catch their prey. They have male and female forms and an interesting alternation of generations-type reproductive system with the medusa (free-swimming) form being the form most people think of as jellyfish.

Planktonic animals, our jellies are found across the Atlantic and in their free-swimming form tend to be washed in on warm waters in Spring, Summer and into Autumn after feeding well on plankton and/or breeding.

We have found our most common jellies arriving on our shores in stages from May with the Moon jellies (Aurelia aurita), then the Compass jellies (Chrysaora hysoscella), then Lion’s Manes (Cyanea capillata) during the summer months and Barrels (Rhizostoma octopus) being seen through the year. More recently, they’ve been coming in altogether.

Sitting there on shore they are waiting to be recorded and logistically it’s straight forward on a walk along the shore; taking pictures and logging numbers seen. It’s not always easy to identify them, however. Some have little in the form of colour or markings, others may have lost these as they’ve aged, or lost substance while drying out on shore. Sometimes the found item is only a part of the animal.

For our most common jelly species look for brown dots on the bell edge and/or lines radiating from the centre of the bell for the Compass jelly. The Moon jelly is no bigger than a side plate with, if intact, four central pink circles within the bell. The Barrel can have a blue or reddish hue (but not colour) and has an overall chunky look to it. The Lion’s Mane is red-orange in colour, large and looks almost fluffy. The Blue jelly (Cyanea lamarckii) is its smaller relative and deep blue in colour, rather than red.

Another coloured species is the rarer Mauve Stinger (Pelagianoctiluca), which is pale purple-pink in colour and generally quite small. Over the past couple of years, we’ve also had sightings of a relatively newer to the UK species, the Crystal jelly (Aequoreavictoria).

We’re recording these washed-up items as well as other strandline items, as part of our new Nature Counts project. Linking Citizen Science recording on our reserves with that happening on shore around North Wales. For strandline species, please use the Beached! project on the Cofnod ORS.