Flying freshwater jellyfish

On March 11, 1950, The Mail, a newspaper published in Adelaide, South Australia, ran the headline “Tiny African jellyfish SA reservoir”. A freshwater? Who would not be interested by that? Admittedly, paper did get some stuff wrong: this creature, Craspedacusta sowerbii (Figure 1), is from “Great Lakes of Tanganyika”, as story implies. And journalist’s scientific source, Mr Ifor Thomas Adelaide University, perhaps misquoted saying it was first found outside Africa London’s Kew Gardens 1880s, having arrived on water lilies destined for collection. That’s quite right either (see below). But let’s forgiving: sighting freshwater jellyfish, an absolute novelty most people! just fascinating, made clear, how could have got to Australian reservoir. Well, couldn’t flown there…could it? T Bamford/B O’Brien, U Waikato In fact, there much more than “Down Under” conundrum here, little animal, usually seen ~25-mm diameter medusa, has popped up all over world. With exception Antarctica, literature now records appeared everywhere China Chile, lakes and ponds, natural man-made, sometimes entirely without connection other bodies water. Indeed, scientifically documented back 1880, after somehow penetrating Victoria amazonica tank at Royal Botanic Society’s facilities Regent’s Park (London, UK). E Ray Lankester, who examined strange new creature (and within four days saw his work June 17th issue Nature, then repeated Science July 17th!), speculated that had its way West Indies. However, he noted provenance very difficult trace since no plants recently been added lily house, drained off every year. It’s thought C originates catchment area Yangtze River China. There, blooms medusae both sexes frequently occur ponds pools, while places these flourishes are nearly always composed males or females. “For example, New Zealand we appear males, but Ireland so far observed females”, explains Ian Duggan (University Waikato; Hamilton, Zealand). “The US Sweden females, locations sex seem separate different times. Where they invaded rare find blooming together.” Perhaps conditions unsuitable bloom simultaneously. unisex clouds may simply reflect gender colony founder, which begins life immobile polyp stuck rock. It reproduces asexually budding polyps. From time polyps also bud free-swimming form: typically notice. form, however, provides clue species might disperse. When environmental tough, can turn into cysts called podocysts. These metabolically dormant, drought-resistant capsules conceivably spread passively hitching rides (thus reaching Society eventually contaminating tank), boats, allowing them invade waterways. does isolated where boat goes? Via introduced fish? angling gear? Maybe. flying – with “Waterfowl Airways”. Many authors suggested such aerial arrivals, waterbirds shown carry propagules certain invertebrate their bodies, direct evidence exists podocysts ever getting ground. “As I am aware, one attached proverbial ‘duck’s feet’, highly plausible being moved waterfowl”, says Duggan. “Our surveys North Island showed stage widespread among around island, including number medusa never found. Not only were widespread, fairly isolated, any kind access, dispersal associated waterfowl seems plausible.” if Duggan’s tiny latter when gets above 20°C maybe (Aquat Invasions 2012; 7: 271–75). small centuries traveling globe, silently conquering pools form resistant podocyst passengers, (or even within?) waterbirds, long noticed medusae. You say actually out thin air. Adrian Burton