Tiny opaque ninjas spreading in the warm oceans of the world

There is a massive silent invasion of stinging invertebrates spreading through the warming oceans of the world. At first unnoticed, these silent pinkish opaque floating bells with dangling tentacles can transform from an adult back into its juvenile stage, over and over again as an emergency survival measure.
Those may look like tentacles on this ninja of the ocean ( see image below), but in reality they are the weapons of rapid expansion of a stealthy marine invasion. They silently tag a ride in a ship’s ballast water and travel to new homes around the world.

The life history of Turritopsis dohrnii takes such twists and turns that only a new genetic analysis has revealed that the creature is invading waters worldwide, says Maria Pia Miglietta of Pennsylvania State University in University Park.

The first peculiarity of the seven species of Turritopsis had inspired biologists to describe these hydrozoans as “potentially immortal.” The adults form filmy bells resembling their jellyfish relatives. When times get tough, faced with scarce food or other catastrophe, Turritopsis often don’t die. They just get young again or go back to the medusa or earlier stage of its development.

Normally the organisms reproduce like grown-ups with sperm and eggs. In case of emergency, though, a bedeviled bell sinks down and the blob of tissue sticks to a surface below. There Turritopsis’ cells seem to reverse their life stage. When the blob grows again, it becomes thelifecycle-of-turritopsis stalklike polyp of its youth and matures into a free-floating bell all over again. “This is equivalent to a butterfly that goes back to a caterpillar,” Miglietta says.

That’s a fine trick for surviving the strains of being swallowed in a huge gulp of water for a ship’s ballast and being hauled around the world, Miglietta says. The creatures can restart their life cycles right in the bottom of the ballast tank. Ballast water has become the major route for moving alien species from one ocean to another, and that’s probably what’s happening to T. dohrnii, Miglietta said June 21 in Minneapolis during the Evolution 2008 meeting.

DNA analysis of these reversible hydrozoans shows signs of recent travel, she said. She and colleague Harilaos Lessios of the Smithsonian Tropical Research Institute compared mitochondrial DNA from T. dohrnii collected off Florida and Panama with DNA sequences from around the world. The DNA sequences of all those sampled whether they were from from Panama, Japan, Spain, Italy, or the Atlantic side of Panama were similar. To get that pattern, there’s been some fast travel going on.

Miglietta said that the DNA revealed a new peculiarity of the hydrozoan lifestyle, around Panama, the 259 adults she examined had eight tentacles however in temperate waters, have found higher, more variable numbers of tentacles, such as 14 to 24 off Japan and 12 to 24 in the Mediterranean. Through research these jelly fish ninjas all belong to the same species.

These hydrozoans do not seem to disrupt the ecosystems they’re invading.

That statement drew heartfelt agreement from John Darling of the U.S. Environmental Protection Agency’s National Exposure Research Laboratory in Cincinnati. Genetics has also revealed hidden twists in a marine invasion he described at the Evolution meeting.


Excerpts courtesy of Sciencenews.org


Image courtesy of Developmental Biology OnLine




  1. February 3, 2009 at 5:30 am

    […] Tiny opaque ninjas spreading in the warm oceans of the world b…/b […]

  2. donmitchel said,

    February 3, 2009 at 5:32 pm

    To whom it may concern Once again we have the start of new ballast legislation in both the house and senate h.r.500 and s237. It is again time for those who care to begin looking for the loop holes and to make sure that we try to enact meaningful legislation that will set our country on a course to protect ourselves from both the accidental devastation caused by invasive s and the possibility of foreign sea captains and terrorist being in charge of what is being dumped in our waters, trying to do us harm. Being that h.r.2830 was left to die in the senate because senator Boxer of California wanted tougher regulations we should make sure and accommodate this so all Americans will receive equal protection of their water by the Federal Government. Please let your politicians know what is needed in future laws and regulations. Sincerely Don Mitchel

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