NEWS - Tardigrades are indestructible, a superpower that helped them survive the deadliest mass extinction in Earth’s history. The microscopic creature, also called water bears and moss piglets, can withstand extreme heat, cold, pressure and radiation.
They survived for 252 million years in a hostile environment through a process called cryptobiosis, in which most of the body’s water is lost and reabsorbed as metabolism slows down.
Cryptobiosis occurred 359 million to 299 million years ago, before a deadly event known as the Permian extinction event that occurred about 252 million years ago and wiped out 96 percent of marine life and 70 percent of terrestrial life. Cryptobiosis may have helped tardigrades survive the event.
Marc Mapalo, Joanna Wolfe and Javier Ortega-Hernández of the Museum of Comparative Zoology and the Department of Organismic and Evolutionary Biology at Harvard University analyzed tardigrade fossils in amber and are the first to estimate when this ability evolved.
Four fossils preserved in amber date from 84 million to 71 million years ago, and one species, Beorn leggi, was described in 1963. The researchers used high-contrast microscopy to reveal distinct claw details, but the body shape has changed little over millions of years.
Aerobius dactylus was named a new species, and B. leggi was given a new classification based on the joints in its claws. Both species were placed in the superfamily Hypsibioidea, and B. leggi was moved to the family Hypsibiidae. Recalibrating the family tree allowed the researchers to calculate when the two ancestral lines diverged.
The discovery of additional fossils could help shed light on the emergence of this unique survival strategy. The results of this study should alert other researchers to the fact that there are still many tardigrade fossils that have not been discovered today.
Original research
Mapalo, M.A., Wolfe, J.M. & Ortega-Hernández, J. Cretaceous amber inclusions illuminate the evolutionary origin of tardigrades. Nature communications 7, 953 (2024). DOI:10.1038/s42003-024-06643-2
They survived for 252 million years in a hostile environment through a process called cryptobiosis, in which most of the body’s water is lost and reabsorbed as metabolism slows down.
Cryptobiosis occurred 359 million to 299 million years ago, before a deadly event known as the Permian extinction event that occurred about 252 million years ago and wiped out 96 percent of marine life and 70 percent of terrestrial life. Cryptobiosis may have helped tardigrades survive the event.
Marc Mapalo, Joanna Wolfe and Javier Ortega-Hernández of the Museum of Comparative Zoology and the Department of Organismic and Evolutionary Biology at Harvard University analyzed tardigrade fossils in amber and are the first to estimate when this ability evolved.
Four fossils preserved in amber date from 84 million to 71 million years ago, and one species, Beorn leggi, was described in 1963. The researchers used high-contrast microscopy to reveal distinct claw details, but the body shape has changed little over millions of years.
Aerobius dactylus was named a new species, and B. leggi was given a new classification based on the joints in its claws. Both species were placed in the superfamily Hypsibioidea, and B. leggi was moved to the family Hypsibiidae. Recalibrating the family tree allowed the researchers to calculate when the two ancestral lines diverged.
The discovery of additional fossils could help shed light on the emergence of this unique survival strategy. The results of this study should alert other researchers to the fact that there are still many tardigrade fossils that have not been discovered today.
Original research
Mapalo, M.A., Wolfe, J.M. & Ortega-Hernández, J. Cretaceous amber inclusions illuminate the evolutionary origin of tardigrades. Nature communications 7, 953 (2024). DOI:10.1038/s42003-024-06643-2