Turritopsis nutricula
Encyclopedia
Turritopsis nutricula, the immortal jellyfish, is a hydrozoa
n whose medusa, or jellyfish
, form can revert 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. It does this through the cell development process of transdifferentiation
. Cell transdifferentiation is when the jellyfish "alters the differentiated state of the cell and transforms it into a new cell". In this process the medusa of the immortal jellyfish is transformed into the polyps of a new polyp colony. First, the umbrella reverts itself and then the tentacles and mesoglea get resorbed. The reverted medusa then attaches itself to the substrate by the end that had been at the opposite end of the umbrella and starts giving rise to new polyps to form the new colony. Theoretically, this process can go on indefinitely, effectively rendering the jellyfish biologically immortal
, although in nature, most Turritopsis, like other medusae, are likely to succumb to predation or disease in the plankton
stage, without reverting to the polyp form. No single specimen has been observed for any extended period, so it is not currently possible to estimate the age of an individual, and so even if this species has the potential for immortality, there is no laboratory evidence of many generations surviving from any individual.
Turritopsis nutricula also has a bottom-living polyp form, or hydroid, which consists of stolons that run along the substrate, and upright branches with feeding polyps that can produce medusa buds. These polyps develop over a few days into tiny 100 mm medusae, which are liberated and swim free from the parent hydroid colony.
Images of both the medusa and polyp of the closely related species Turritopsis rubra from New Zealand
can be found online. Until a recent genetic study, it was thought that Turritopsis rubra and Turritopsis nutricula were the same. It is not known whether or not T. rubra medusae can also transform back into polyps.
scientist Dr. Maria Pia Miglietta.
larvae, which settle onto the sea floor (or even the rich marine communities that live on floating docks), and develop into polyp colonies (hydroids). The hydroids bud new jellyfishes, which are released at about 1 mm in size and then grow and feed in the plankton, becoming 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 (71.6 °F) it is 18 to 22 days).
s, and finally feeding polyps. Polyps further multiply by growing additional stolons, branches and then polyps, to form colonial hydroids. This ability to reverse the life cycle (in response to adverse conditions) is probably unique in the animal kingdom, and allows the jellyfish to bypass death, rendering Turritopsis nutricula potentially biologically immortal
. Studies in the laboratory showed that 100% of specimens could revert to the polyp stage, but so far the process has not been observed in nature, in part because the process is quite rapid and field observations at the right moment in time are unlikely. In spite of this remarkable ability, most Turritopsis medusae are likely to fall victim to the general hazards of life as plankton
, including being eaten by other animals, or succumbing to disease.
Hydrozoa
Hydrozoa are a taxonomic class of very small, predatory animals which can be solitary or colonial and which mostly live in saltwater. A few genera within this class live in freshwater...
n whose medusa, or jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
, form can revert to the polyp
Polyp
A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are approximately cylindrical in shape and elongated at the axis of the body...
stage after becoming sexually mature
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
. It is the only known case of a metazoan
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary stage. It does this through the cell development process of transdifferentiation
Transdifferentiation
Transdifferentiation in biology takes place when a non-stem cell transforms into a different type of cell, or when an already differentiated stem cell creates cells outside its already established differentiation path...
. Cell transdifferentiation is when the jellyfish "alters the differentiated state of the cell and transforms it into a new cell". In this process the medusa of the immortal jellyfish is transformed into the polyps of a new polyp colony. First, the umbrella reverts itself and then the tentacles and mesoglea get resorbed. The reverted medusa then attaches itself to the substrate by the end that had been at the opposite end of the umbrella and starts giving rise to new polyps to form the new colony. Theoretically, this process can go on indefinitely, effectively rendering the jellyfish biologically immortal
Biological immortality
Biological immortality refers to a stable rate of mortality as a function of chronological age. Some individual cells and entire organisms in some species achieve this state either throughout their existence or after living long enough. This requires that death occur from injury or disease rather...
, although in nature, most Turritopsis, like other medusae, are likely to succumb to predation or disease in the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
stage, without reverting to the polyp form. No single specimen has been observed for any extended period, so it is not currently possible to estimate the age of an individual, and so even if this species has the potential for immortality, there is no laboratory evidence of many generations surviving from any individual.
Description
The medusa of Turritopsis nutricula is bell-shaped, with a maximum diameter of about 4.5 millimetre (0.177165354330709 in) and is about as tall as it is wide. The jelly in the walls of the bell is uniformly thin, except for some thickening at the apex. The relatively large stomach is bright red and has a cruciform shape in cross section. Young specimens 1 mm in diameter have only eight tentacles evenly spaced out along the edge, while adult specimens have 80-90 tentacles. The medusa (jellyfish) is free-living in the plankton.Turritopsis nutricula also has a bottom-living polyp form, or hydroid, which consists of stolons that run along the substrate, and upright branches with feeding polyps that can produce medusa buds. These polyps develop over a few days into tiny 100 mm medusae, which are liberated and swim free from the parent hydroid colony.
Images of both the medusa and polyp of the closely related species Turritopsis rubra from New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
can be found online. Until a recent genetic study, it was thought that Turritopsis rubra and Turritopsis nutricula were the same. It is not known whether or not T. rubra medusae can also transform back into polyps.
Distribution and range
Turritopsis is believed to have originated in the Pacific but has spread all over the world, and has speciated into several populations that are easy to distinguish morphologically, but whose species distinctions have recently been verified by a study and comparison of mitochondrial ribosomal gene sequences. Turritopsis are found in temperate to tropical regions in all of the world's oceans. Turritopsis is believed to be spreading across the world as ships are discharging ballast water in ports. Since the species is immortal, the number of individuals could be rising fast. "We are looking at a worldwide silent invasion" said Smithsonian Tropical Marine InstituteSmithsonian Tropical Research Institute
The Smithsonian Tropical Research Institute in Panama, the only bureau of the Smithsonian Institution based outside of the United States, is dedicated to understanding biological diversity. What began in 1923 as small field station on Barro Colorado Island in the Panama Canal Zone has developed...
scientist Dr. Maria Pia Miglietta.
Life cycle
The eggs develop in gonads of female medusae, which are located in the walls of the manubrium (stomach). Mature eggs are presumably spawned and fertilized in the sea by sperm produced and released by male medusae, as is the case for most hydromedusae, although the related species Turritopsis rubra seems to retain fertilized eggs until the planula stage. Fertilized eggs develop into planulaPlanula
A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species. The planula forms from the fertilized egg of a medusa, as the case in scyphozoans and some hydrozoans, or from a polyp, as in the case of anthozoans...
larvae, which settle onto the sea floor (or even the rich marine communities that live on floating docks), and develop into polyp colonies (hydroids). The hydroids bud new jellyfishes, which are released at about 1 mm in size and then grow and feed in the plankton, becoming 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 (71.6 °F) it is 18 to 22 days).
Biological immortality
Most jellyfish species have a relatively fixed life span, which varies by species from hours to many months (long-lived mature jellyfish spawn every day or night; the time is also fairly fixed and species-specific). The medusa of Turritopsis nutricula is the only form known to have developed the ability to return to a polyp state, by a specific transformation process that requires the presence of certain cell types (tissue from both the jellyfish bell surface and the circulatory canal system). Careful laboratory experiments have revealed that all stages of the medusae, from newly released to fully mature individuals, can transform back into polyps. The transforming medusa is characterized first by deterioration of the bell and tentacles, with subsequent growth of a perisarc sheet and stolonStolon
In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...
s, and finally feeding polyps. Polyps further multiply by growing additional stolons, branches and then polyps, to form colonial hydroids. This ability to reverse the life cycle (in response to adverse conditions) is probably unique in the animal kingdom, and allows the jellyfish to bypass death, rendering Turritopsis nutricula potentially biologically immortal
Biological immortality
Biological immortality refers to a stable rate of mortality as a function of chronological age. Some individual cells and entire organisms in some species achieve this state either throughout their existence or after living long enough. This requires that death occur from injury or disease rather...
. Studies in the laboratory showed that 100% of specimens could revert to the polyp stage, but so far the process has not been observed in nature, in part because the process is quite rapid and field observations at the right moment in time are unlikely. In spite of this remarkable ability, most Turritopsis medusae are likely to fall victim to the general hazards of life as plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
, including being eaten by other animals, or succumbing to disease.
Benefits for Humans
The turriptosis nutricula's cell development method of transdifferentiation has inspired scientists to find a way to make stem cells use this process for renewing damaged or dead tissue in humans. Also, it is believed that the immortal jellyfish may hold the answer to cure cancer and create anti-aging medication.See also
- List of long-living organisms
- Biological immortalityBiological immortalityBiological immortality refers to a stable rate of mortality as a function of chronological age. Some individual cells and entire organisms in some species achieve this state either throughout their existence or after living long enough. This requires that death occur from injury or disease rather...
- HydraHydra (genus)Hydra is a genus of simple fresh-water animal possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa. They can be found in most unpolluted fresh-water ponds, lakes, and streams in the temperate and tropical regions and can be found by...
– another kind of cnidarian that is claimed to be immortal