Chris Turner
You’re growing old, fragile and, perhaps worst of
all, wrinkly. If only you could go back to being a baby, and grow up all over
again. This might sound like a curious fantasy but for one member of the animal
kingdom it’s just part of life.
Turritopsis
nutricula is the Immortal Jellyfish. As a member of the Hydrozoa class, it
has two stages within its life cycle: the polypois and medusoid stages. In polyp form these jellyfish are grouped together
in colonies, with several polyps connected in a tree-like manner by a series of
tubes called hydrocauli. These polyps are little more than mouths, terrifying
mouths covered in vicious, stinging tentacles. It’s certainly comforting to
know they’re less than one millimetre tall. The medusa stage is the larger, sexually mature
form sizing up to a slightly underwhelming 4.5 mm. It’s a more conventional jellyfish
shape with around 100 stinging tentacles trailing below a bright red stomach.
Unlike all other Hydrozoans, the transformation
from polyp to medusa isn’t a one way street for Turritapsis. When conditions are unfavourable the jellyfish is able
to use cells from certain tissues to revert back, with its bell and tentacles
deteriorating in exchange for hydrocauli. This ability to reverse metamorphose
means that the jellyfish is biologically immortal. With this extraordinary trait it isn’t much of a
surprise to hear that this species is quickly spreading across the oceans. According
to Dr Maria Miglietta of the Smithsonian Tropical Marine Institute we’re seeing
‘a worldwide silent invasion’. Let’s hope they don’t get much bigger.
Did you know Synapse featured The Immortal Jellyfish in issue 3 of our print magazine? It made it onto the front cover!
