{"id":22267,"date":"2023-01-03T19:00:09","date_gmt":"2023-01-03T18:00:09","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=130800"},"modified":"2023-01-03T20:35:16","modified_gmt":"2023-01-03T19:35:16","slug":"what-is-hallucigenia","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/what-is-hallucigenia\/","title":{"rendered":"What is hallucigenia?"},"content":{"rendered":"

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By Helen Pilcher\n \t\t<\/p>

Published: Tuesday, 03 January 2023 at 12:00 am<\/p>

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Named for its \u2018bizarre and dream-like\u2019 appearance, hallucigenia was a finger-sized ocean-dweller that lived during the Cambrian Period around 508 million years ago. It belonged to a group called the panarthropods, which later gave rise to velvet worms<\/a>, water bears<\/a> and arthropods.<\/p>\n

In 1977, British palaeontologist Simon Conway Morris<\/a> determined that it had seven pairs of stilt-like legs sticking down, and seven pairs of mouth-tipped tentacles pointing up. Then more specimens were analysed, and this interpretation was turned upside down\u2026 literally. Scientists realised that the \u2018tentacles\u2019 were, in fact, claw-tipped legs that pointed down, and the \u2018legs\u2019 were actually pointy spines that protruded upwards.<\/p>\n

Hallucigenia was now the right way up, but no one knew which end was the head. Then in the mid-2000s, modern microscopy methods were applied, and hey presto, the longer of the two \u2018sticky-out bits\u2019 was found to contain, not just eyes, but a mouth too. Behind the head, three hitherto unknown pairs of appendages were discovered, and the legs were shown to be jointless.<\/p>\n

Hallucigenia, it\u2019s thought, may have walked by altering the pressure of the fluid inside its legs, much like a modern-day starfish.<\/p>\n