FishSpotterby
Back to the feed

Jellyfish

Blue Jellyfish

Cyanea lamarckii

Cyanea lamarckii Péron & Lesueur, 1810 · Cyaneidae WoRMS 135302

Reference photos

Tap a photo to enlarge.

A smaller cousin of the lion's mane. The bell runs from translucent or pale yellow to light blue or purple, and in faintly coloured animals the blue outlines the sculpting inside it. Eight groups of 40 to 60 hollow tentacles trail beneath. It stings.

Depth

Pelagic, recorded from the surface down to 150 m

Size

Bell up to 30 cm across, and rarely larger

Habitat

Pelagic in coastal waters, drawn inshore by blooms of plankton

Behaviour

Drifts in open water, catching prey on a dense array of stinging tentacles; seen inshore from May to October

Diet

I eat

  • Copepods and other crustaceans taken from the plankton
  • Fish eggs and larvae, including clupeids

Eats me

  • The amphipod Hyperia galba, an obligate parasite that lives inside the medusa and cannot survive without a host

Where you'd find it

Found around most of Britain and Ireland, though less often in the Celtic Sea.

ChannelCeltic SeaNorth SeaIrish SeaW of IrelandW of Scotland
Often seenNow and thenWhere PEBL filmsBased on marine survey records (OBIS). Blank seas can mean nobody has looked there, not that the animal is absent.

Sources

Open-access references behind this page. Every statement on this page was read out of one of them; anything that could not be traced to a source was taken off the page rather than left standing. Each link was checked on the date shown, and confirmed then to be about this species.

Name Blue Jellyfish in a clip to add it to your collection.

Spot it in the feed