It ’s a good affair animals do n’t live the names we give them , never more so than penis worms ( Priapulida ) . After all , they might contend , they were here 530 million days before us and our genitalia . Now it turn out penis worms were n’t just hanging around in the ocean looking phallic - like , they do up with a method acting for avoiding piranha since made notable by hermit Cancer .
Like so many other foreign - looking animals , penis worm ( not to be confused withpenis fish ) appeared during the Welsh earned run average , but unlike most , they survived , and have n’t changed all that much since . While related invertebrates such as arthropod have diversified spectacularly , penis worm have just stuck with what works , unbothered by what humans think .
Having had a “ no bones day ” for half a billion years , penis worms do n’t fossilize very well . Nevertheless , they have been so abundant and often live in places so well suited to making fossils that we have a phonograph recording of their existence in position like the Guanshan sedimentation in China . Now , a new paper inCurrent Biologyhas break four specimen from Guanshan and the shell in which they were found , suggest they had adopted thehermit crablifestyle millions of years before hermit crabs .
Dr Martin Smithof Durham University and atomic number 27 - authors report the bearing of four penis worms of the genusEximipriapulusinside hyolith ( bottom - dwelling conical shell builders ) shell . One might have been a concurrence , but four could n’t be explain that elbow room , peculiarly since noEximipriapulushave been found outside shells in the orbit .
“ The worms are always baby-sit snugly within these same types of eggshell , in the same position and orientation ” Smith observe in astatement . “ The only account that made gumption was that these shells were their rest home – something that came as a existent surprise . " .
Hermit crabs proveoccupying shells made by otherscan be a full way to escape predators without induce to go through all the worry of building a dwelling yourself . We know of other exemplar stretching back to the mid - Jurassic , but Smith and co - authors were surprised by the penis worms ' indigence for shelter so betimes .
“ Not long before these organism exist , there was nothing alive more complex than seaweeds or jellyfish , ” Smith said . “ So it ’s mind - boggling that we start to see the complex and dangerous bionomics normally associated with much younger geological periods so soon after the first complex animals get on the tantrum . ”
Penis worms were predators in their own right wing , but at less than an inch long the authors found there were plenty further up the food chain in the Guanshan ecosystem to threaten them . The intense predation pressure shaped the behavior of those under threat . The newspaper notes this is a rarefied grammatical case of fossils continue evidence of Cambrian behavior . Along with the late find ofcommunal thermionic tube - buildingin the Burgess Shale , the finding suggests the Cambrian was more like mod times than previously admit .
