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| Ancient crayfish and worms may die out together | Ancient crayfish and worms may die out together |
| (about 1 hour later) | |
| Research suggests that bizarre, tentacled worms which live attached to crayfish in the rivers of Australia are at risk of extinction - because the crayfish themselves are endangered. | Research suggests that bizarre, tentacled worms which live attached to crayfish in the rivers of Australia are at risk of extinction - because the crayfish themselves are endangered. |
| It would be an example of coextinction, where one organism dies out because it depends on another doomed species. | It would be an example of coextinction, where one organism dies out because it depends on another doomed species. |
| Just a few millimetres long, the worms eat even tinier critters in the water or inside the crayfish gill chamber. | Just a few millimetres long, the worms eat even tinier critters in the water or inside the crayfish gill chamber. |
| Their symbiotic relationship stretches back at least 80 million years. | Their symbiotic relationship stretches back at least 80 million years. |
| The new study maps out that shared history based on genetic analysis of 37 different species of spiny mountain crayfish and 33 varieties of their "temnocephalan" flatworm passengers. | |
| It was a collaboration between Australian and UK scientists, and appears in the Proceedings of the Royal Society B. | |
| "We've now got a picture of how these two species have evolved together through time," said Dr Jennifer Hoyal Cuthill from the University of Cambridge. | "We've now got a picture of how these two species have evolved together through time," said Dr Jennifer Hoyal Cuthill from the University of Cambridge. |
| She and her colleagues conclude that it was some 80-100 million years ago that these two types of animal started to evolve together. | She and her colleagues conclude that it was some 80-100 million years ago that these two types of animal started to evolve together. |
| The Australian continent was about halfway through its gradual northward march to its current position on the globe and as it progressed, the creatures' habitat started to fragment and shrink. | The Australian continent was about halfway through its gradual northward march to its current position on the globe and as it progressed, the creatures' habitat started to fragment and shrink. |
| Today, spiny mountain crayfish - a genus called Euastacus - live in dwindling patches of eastern Australia. In the northern part of their range, they are restricted to high-altitude rainforest streams. | Today, spiny mountain crayfish - a genus called Euastacus - live in dwindling patches of eastern Australia. In the northern part of their range, they are restricted to high-altitude rainforest streams. |
| It is those northern lineages, which also tend to be the most distinctive in their physiology and their DNA, which are most endangered. The worms show a very similar pattern. | It is those northern lineages, which also tend to be the most distinctive in their physiology and their DNA, which are most endangered. The worms show a very similar pattern. |
| "The extinction risk to the crayfish has been measured, but this is the first time we've quantified the risk to the temnocephalans as well - and it looks like this ancient partnership could end with the extinction of both species," Dr Hoyal Cuthill said. | "The extinction risk to the crayfish has been measured, but this is the first time we've quantified the risk to the temnocephalans as well - and it looks like this ancient partnership could end with the extinction of both species," Dr Hoyal Cuthill said. |
| Currently, about 75% of all Euastacus crayfish species are endangered. The scientists found that if all those species were to die out, some 60% of the temnocephalans would also disappear. | Currently, about 75% of all Euastacus crayfish species are endangered. The scientists found that if all those species were to die out, some 60% of the temnocephalans would also disappear. |
| They say this is a genuine threat, particularly as modern-day climate change steepens the warming of Australia that has shaped and shrivelled the creatures' shared habitat over the millennia. | They say this is a genuine threat, particularly as modern-day climate change steepens the warming of Australia that has shaped and shrivelled the creatures' shared habitat over the millennia. |
| "In Australia, freshwater crayfish are large, diverse and active 'managers', recycling all sorts of organic material and working the sediments," said the study's senior author, Prof David Blair of James Cook University in Townsville, Australia. | "In Australia, freshwater crayfish are large, diverse and active 'managers', recycling all sorts of organic material and working the sediments," said the study's senior author, Prof David Blair of James Cook University in Townsville, Australia. |
| "The temnocephalan worms associated only with these crayfish are also diverse, reflecting a long, shared history and offering a unique window on ancient symbioses. We now risk extinction of many of these partnerships, which will lead to degradation of their previous habitats and leave science the poorer." | "The temnocephalan worms associated only with these crayfish are also diverse, reflecting a long, shared history and offering a unique window on ancient symbioses. We now risk extinction of many of these partnerships, which will lead to degradation of their previous habitats and leave science the poorer." |