Red-Eye Medusa (Jellyfish)

It’s a tiny jellyfish ringed with red.

The Red-Eye Medusa spends most of its time in dark waters near the ocean floor, yet we were lucky enough to see these jellies swimming near the surface of a calm, protected nook in Harlequin Bay on Hurst Island in God’s Pocket Marine Provincial Park this week. The sighting was a real treat, as these jellies don’t usually hang out at the surface when the sun in shining!

Here are a few facts about this pretty little jellyfish:

  • The name “Red Eye Medusa” comes from the ring of tiny red eyespots that line the bottom of the jelly’s bell — one eyespot at the base of each of its 100 to 160 tentacles.
  • The eyespots are light sensitive and thought to help the jelly move from the ocean bottom to the water’s surface at night, where it possibly comes to feed or spawn.
  • The medusa is small — with a bell up to 6 cm tall and 2 cm wide — however its tentacles can expand to several times its length or crunch up to just a fringe under its bell.
  • The older the jelly, the more tentacles it has. Kind of like wrinkles for humans?
  • This jelly frequents protected bays and eelgrass beds in nearshore waters along the Pacific coast. It likes the dark and spends most of its time within a few meters of the ocean floor.
  • The medusa feeds by “bouncing” off the ocean floor to stir up prey, then floating down to snare food in its tentacles. Zooplankton, small crustaceans and tiny worms are its favourite meals.
  • The jelly also hunts in the water column using a method called sink fishing: it hangs its tentacles to their full length then floats gently downward catching prey as it goes.
  • These medusae spawn on the surface, in the hour immediately after dark. Females produce about 10,000 eggs per day, which they release in the span of about 10 minutes.
  • Despite prolific egg production, this jelly is in decline in BC. Suspected causes? Habitat destruction due to seafloor dredging, water pollution, and over-collection for research and aquariums.
  • Lifespan is unknown but is thought to be just a few months.

All photos courtesy Jeff Burdison, Magnetic North Sea Kayaking.

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