Invasive ctenophores Mnemiopsis leidyi in the North of its range larvae feed on his own kind, when their normal food is not enough, it is reported in the Communications Biology. Towards the end of the warm season, when zooplankton are already getting low, they still actively proliferate, thereby creating a reserve of food from their own starving descendants. This unusual strategy allows Mnemiopsis to gain a foothold in the cold seas where the cold period of starvation lasts too long.
The types of the intruders (invasive species) is actively expanding its range and significantly changing ecosystem that get. Often mention that their success is associated with the absence of predators and competitors, however, none of the body won’t be able to live where he himself did not have enough food. Therefore, we can explain how the ctenophore Mnemiopsis who originally lived in the West Atlantic ocean, were multiplied in large quantities in the warm Black sea (now its population there keep using another ctenophore), but harder to understand how he manages to survive in colder and winter poor zooplankton in the Baltic sea.
Off the coast of North America , Mnemiopsis leidyi was not found above 42 degrees North latitude, and in European waters it can be found on the 58th parallel. It is more interesting that the Mnemiopsis has no specialized life stages winter rest, and when propagated, often explosively, accompanied by a almost all of the available food. Off the coast of Germany it continues to release into the water sperm and eggs and at the end of August, although larvae that emerge from fertilized during this time, eggs do not survive until spring. They exist for two to three weeks, and after this period, lose weight because starve and die. It is unclear why the Baltic Mnemiopsis need this kind of wasteful later reproduction.
Researchers from Australia and several European countries, led by Thomas Larsen (Thomas Larsen) from the Institute of world history, max Planck Society from 12 August to 21 October 2008 considered the number of adult individuals and larvae Mnemiopsis leidyi from Keeler-Forde, and each week has estimated the mass of zooplankton in the Gulf. They noticed that on 1 September, the number of ctenophores was the maximum, and at this time of zooplankton was enough. A week later she was falling. Especially rapidly decreased the number of larvae of ctenophores, and zooplankton also have been of little. There was an assumption that adults eating the young.
It was confirmed later, in September 2016, laboratory experiments. Adults 36 hours were kept together with larvae, which were injected with the isotope nitrogen-15. Then measured the concentration of this isotope in adult ctenophores and compared it with that of adult animals from the control group, which the same time had no larvae. In the first case it was significantly higher (P = 0.008). Elemental analysis showed that adult ctenophores for a day and a half received from larvae 4.1 percent of all carbon atoms of his body and 2.5 percent of the nitrogen atoms. This is the first direct evidence that Mnemiopsis leidyi in for cannibalism in the Northern parts of their current advanced area.
Eating members of their same species is fairly widespread in nature, often the victims are that small, young individuals, and usually the animals are moving to cannibalism if no other food sources become inaccessible. Mnemiopsis in a sense, are ahead of the curve: at a time when the amount of their usual food yet not too little, they produce live food for the future — late larvae, which are doomed in the fall to be eaten by larger individuals. Probably, this knowledge will help to regulate the number of Mnemiopsis leidyi and thus stop its spread in new areas.
The study was not reported, whether ctenophores eaten those maggots that they have parents. And as some fishes and amphibians it is known that they sometimes eat their species, but do not touch her babies and even actively protect them from cannibalism by other individuals.