Immortal jellyfish lifespan and age in human years
Average lifespan Biologically immortal (can revert to youth)
The immortal jellyfish can revert to its juvenile polyp stage after reaching adulthood, so in theory it may never die of old age.
Sources
How we convert ages: method.
More Sea life
Bottlenose dolphinLifespan about 40 years
Killer whaleLifespan about 50 years
Bowhead whaleLifespan up to 211 years (record)
Blue whaleLifespan about 85 years
Sea otterLifespan about 15 years
Spotted sealLifespan up to 38 years (record)
Green sea turtleLifespan about 70 years
Greenland sharkLifespan up to 392 years (record)
Whale sharkLifespan up to 54 years (record)
Common octopusLifespan about 12 months
American lobsterLifespan up to 100 years (record)
Giant squidLifespan up to 35 years (record)