Scientists Find World's Tiniest Vertebrate
日前，科学家在印度尼西亚的沼泽地里发现了世界上最小的脊椎动物——一种仅为7.9毫米长的鱼。
据《泰晤士报》1月25日报道，这种鱼名为P.
progenetica（Paedocypris progenetica），其成年的雌鱼只有7.9毫米长，它们以0.1毫米的优势击败了此前被认为是世界上最小的脊椎动物——8毫米长的印度洋－太平洋的虾虎鱼。P.
progenetica鱼的身体呈透明状，生活在深茶色的高酸性沼泽环境中。沼泽中pH值为3，是一般酸雨酸性的100多倍。研究人员说，雄性的P.
progenetica可以长到8.6毫米长，且鱼鳍很大，这种体形有利于它们在求偶期吸引雌鱼。
英国伦敦自然历史博物馆的动物学家布利兹领导的科考队在印度尼西亚的苏门答腊岛的一片高酸性泥煤沼泽地中发现了这种微小的鱼类。布利兹博士说：“这是我整个职业生涯见过的最奇怪的鱼。它太小了，又生活在高酸性环境里，而且还有相对于身体巨大的奇怪的鳍。我希望能在这种鱼的生存环境彻底消失之前更多地发现它们。”
1997年，P. progenetica生活的这种泥煤沼泽地被森林大火所破坏，如今这种沼泽地也面临着人类伐木、城市化进程和开荒种田等行为的威胁。科学家认为，其中许多P.
progenetica已经灭绝。布利兹指出：“这种曾经遍及东南亚的泥煤沼泽地如今已经消失了许多，而生活在其中的动物也在濒临灭绝。”
布利兹等人的最新发现被刊登在了最新一期的英国《伦敦皇家学会会报，B辑》上。
报道说，目前，世界上最小的哺乳动物为生活在泰国的一种名为Craseonycteris
thonglongyai的蝙蝠，它的长度2.9厘米至3.3厘米。
The smallest animal with a backbone known to science, a fish from the
carp family, has been discovered in the peat swamps of Indonesia.
Mature females of the fish species Paedocypris progenetica
reach just 7.9mm (3/10 in) in length, making them the smallest vertebrates yet
identified by a tenth of a millimetre.
The previous size record for a vertebrate was held by the
Indo-Pacific goby, another fish, at 8mm. Britain's smallest fish, and
vertebrate, is the marine Guillet's goby, Lebetus guilleti, which measures 24mm.
The species was discovered in the highly acidic peat
swamps of the Indonesian island of Sumatra by a team led by Ralf Britz, a
zoologist at the Natural History Museum in London.
"This is one of the strangest fish that I've seen in
my whole career," Dr Britz said.
"It's tiny, it lives in acid and it has these bizarre
grasping fins. I hope that we'll have time to find out more about them before
their habitat disappears completely."
The species is transparent and lives in dark tea-coloured
swamp waters, which at pH3 are 100 times more acidic than rainwater. Although
these swamps were once thought to harbour very few animals, recent research has
shown that they are home to a highly diverse range of species that occur nowhere
else.
The peat swamps were damaged by forest fires in 1997, and
are also threatened by logging, urbanisation and agriculture. The scientists
behind the discovery said that several populations of P. progenetica had already
been lost.
"Many of the peat swamps we surveyed throughout
South-East Asia no longer exist and their fauna is eradicated," Dr Britz
said. "Populations of all the highly endemic miniature fishes of peat
swamps have decreased or collapsed."
Details of the discovery are published today in the
journal Proceedings of the Royal Society of London, Series B. The male fish grow
to 8.6mm, and boast enlarged pelvic fins with exceptionally large muscles
relative to the size of the rest of their bodies. The researchers believe that
these may be used for grasping females during sex. The females are smaller
still, reaching 7.9mm.
The smallest known mammal is Kitti's hog-nosed bat,
Craseonycteris thonglongyai, from western Thailand, which measures between 2.9cm
and 3.3cm long.
（ 蒋黎黎）
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