Identification
Affectionately known as the "Pink Helmet," *Aglantha digitale* is a jewel of the high seas. This small hydromedusa is instantly recognizable by its tall, thimble-shaped bell, which is notably higher than it is wide (reaching up to 40mm). While the bell is mostly translucent, it possesses a delicate, iridescent pink or reddish hue. Look closely for its most defining field mark: eight creamy-pink, sausage-shaped gonads hanging prominently from the underside of the subumbrella near the apex. Unlike the flatter "saucer" shapes of many jellies, *Aglantha* looks like a tiny, elegant glass piston.
Habitat & Range
This is a cold-water specialist. You’ll find it in the pelagic zones of the Arctic and Subarctic oceans, as well as the North Atlantic and North Pacific. It is holoplanktonic, meaning it spends its entire life cycle drifting in the open ocean rather than tethered to the seafloor. While it often frequents surface waters during the spring bloom, it can be found at depths of over 1,000 meters.
Behaviour & Diet
Observers will notice *Aglantha* is an exceptionally active swimmer. Unlike many passive drifters, it uses rhythmic pulsations to navigate the water column. It is a voracious predator of copepods and larval crustaceans, using its fringe of up to 80 fine tentacles to snag prey. It exhibits a "stop-and-sink" foraging strategy, spreading its tentacles like a drift net as it slowly descends.
Fascinating Fact
While most jellyfish have primitive nerve nets, *Aglantha digitale* is a biological marvel possessing "giant axons." These specialized nerve fibers allow it to perform a lightning-fast "escape jump" when threatened—a high-velocity contraction that propels it several body lengths in a fraction of a second, a feat of neural engineering rarely seen in such simple organisms!