Turritopsis nutricula
Conservation status
NE
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Hydrozoa
Order:	Anthomedusae
Family:	Clavidae
Genus:	Turritopsis
Species:	T. nutricula
Binomial name
Turritopsis nutricula McCrady, 1857[1]
Synonyms
T. Domhi

Turritopsis nutricula is a hydrozoan which reverts to the polyp stage after becoming sexually mature. It is the only known case of a metazoan capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary stage.^[2] It does this through the cell development process of transdifferentiation.^[3] Theoretically, this cycle can repeat indefinitely, rendering it biologically immortal until its nerve center is removed from the rest of the body.^[3]

Contents 1 Description 2 Distribution and range 3 Life cycle 3.1 Biological immortality 4 See also 5 Further Reading 6 References 7 External links

[edit] Description

Turritopsis nutricula has a diameter of about 4.5 millimetres (0.18 in).^[4] It has an equally high and bell-shaped figure. The walls are uniformly thin. The bright red, big stomach has a cruciform shape in its cross section. Young specimens have only eight tentacles along the edge, while adult specimens have 80-90 tentacles.

[edit] Distribution and range

The species is originally from the Caribbean but has spread all over the world.^[5] T. nutricula are found in temperate to tropical regions in all of the world's oceans.^[4] Turritopsis is believed to be spreading across the world as ships are discharging ballast water in ports.^[4] Since the species is immortal, the number of individuals is spiking. "We are looking at a worldwide silent invasion" said Smithsonian Tropical Marine Institute scientist Dr. Maria Miglietta.^[6]

[edit] Life cycle

The fertilized eggs develop in the stomach and in the screen formed by the cave in the jellyfish planula. The eggs are then planted on the seabed in polyp colonies. The jellyfish hatches after two days. The jellyfish becomes sexually mature after a few weeks (the exact duration depends on the ocean temperature; at 20 °C (68 °F) it is 25 to 30 days and at 22 °C (72 °F) it is 18 to 22 days).

[edit] Biological immortality

Jellyfish usually die after propagating; however, the Turritopsis nutricula has developed the ability to return to a polyp state. This is done through a cell change in the external screen (exumbrella). The cells revert to a different state. The medusa is transformed into a stolon and the polyps into a hydroid colony.^[3] The umbrella turns inside out; middle section and tentacles are reabsorbed before the polyp spawns. Stolons form two days before the polyps differentiate.^[3] The ability to reverse the life cycle is probably unique in the animal kingdom, and allows the jellyfish to bypass death, rendering the Turritopsis nutricula biologically immortal. Laboratory tests showed that 100% of specimens reverted to the polyp stage.^[3]

[edit] See also

• Hydra – another kind of cnidarian that is claimed to be immortal

[edit] Further Reading

• Piraino, S.; Boero, F.; Aeschbach, B.; Schmid, V. (1996), "Reversing the Life Cycle: Medusae Transforming into Polyps and Cell Transdifferentiation in Turritopsis nutricula (Cnidaria, Hydrozoa)", The Biological Bulletin 190 (3): 302, doi:10.2307/1543022, http://www.biolbull.org/cgi/reprint/190/3/302 

[edit] References

[edit] External links

• Cheating Death: The Immortal Life Cycle of Turritopsis
• Telomerase activity is not related to life history stage in the jellyfish Cassiopea sp.
• Turritopsis nutricula at the Encyclopedia of Life

Wikispecies has information related to: Clavidae