Alligators Regrow Tails After Amputation, New Study Finds

American alligators fight near launch pad 39A at Kennedy Space Center in Cape Canaveral, Florida June 7, 2007. REUTERS/Charles W. Luzier (UNITED STATES) - RTR1QK2L (REUTERS/Charles W. Luzier)
American alligators fight near launch pad 39A at Kennedy Space Center in Cape Canaveral, Florida June 7, 2007. REUTERS/Charles W. Luzier (UNITED STATES) - RTR1QK2L (REUTERS/Charles W. Luzier)
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Alligators Regrow Tails After Amputation, New Study Finds

American alligators fight near launch pad 39A at Kennedy Space Center in Cape Canaveral, Florida June 7, 2007. REUTERS/Charles W. Luzier (UNITED STATES) - RTR1QK2L (REUTERS/Charles W. Luzier)
American alligators fight near launch pad 39A at Kennedy Space Center in Cape Canaveral, Florida June 7, 2007. REUTERS/Charles W. Luzier (UNITED STATES) - RTR1QK2L (REUTERS/Charles W. Luzier)

Cornered by a dangerous predator, a gecko can self-amputate its still twitching tail, creating a fleeting moment of distraction - a chance for the lizard to flee with its life.

Small reptiles such as geckos and skinks are well known for this remarkable ability to sacrifice their tails. Now, scientists discovered that much larger alligators can regrow theirs too, but only while they're young.

Researchers from the University of Arizona found that Juvenile American alligators (Alligator mississippiensis) can regrow up to 18 percent of their total body length back (about 23 cm or 9 inches of length). By imaging and dissecting the tail regrowth, researchers found alligators do this quite differently from the other animals we know that can regenerate their appendages. The study was published in the latest issue of the journal Scientific Reports.

While other animals self-amputate themselves, small geckos often lose their tails due to injuries caused by dangerous predators or hunting attempts by humans. In addition to difference in amputation conditions, the researchers observed differences in the mechanism and timing of regrowth.

"If injured, reptiles can reform a segmented skeleton, complete with muscles, while the regrown alligator tail is supported by an unsegmented cartilage tube rather than bone," ASU cellular biologist and first author of the research Cindy Xu said in a report published Saturday on the Science Alert website.

"It also may take them considerably longer to regrow their missing bits. While skinks can do it in as little as six months, a related crocodilian takes up to 18 months to reform their tails," she explained.

The researchers reached these conclusions by studying the final regrowth results of American alligators. But given that they are a threatened species, further studies on how this process works may be challenging, but could provide some useful information.

"If we understand how different animals are able to repair and regenerate tissues, this knowledge can then be leveraged to develop medical therapies," said ASU anatomist and co-author Rebecca Fisher.



Bull Sharks Linger in Warming Sydney Waters

A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)
A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)
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Bull Sharks Linger in Warming Sydney Waters

A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)
A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)

Bull sharks are lingering off Sydney's beaches for longer periods each year as oceans warm, researchers said Friday, predicting they may one day stay all year.

The predators are migratory, swimming north in winter when Sydney's long-term ocean temperatures dip below 19 degrees Celsius (66 degrees Fahrenheit) to bask in the balmier waters off Queensland.

A team of scientists looked at 15 years of acoustic tracking of 92 tagged migratory sharks in an area including Bondi Beach and Sydney Harbour.

Records show the sharks now spend an average of 15 days longer off Sydney's coast in summer than they did in 2009, said James Cook University researcher Nicolas Lubitz.

"If they're staying longer, it means that people and prey animals have a longer window of overlap with them."

Shark attacks are rare in ocean-loving Australia, and most serious bites are from three species: bull sharks, great whites, and tiger sharks, according to a national database.

There have been more than 1,200 shark incidents around Australia since 1791, of which over 250 resulted in death.

Researchers found an average warming of 0.57C in Bondi for the October-May period between 2006 and 2024, said the study published in the peer-reviewed journal Science of The Total Environment.

Over a longer period, remotely sensed summer sea-surface temperatures in the area rose an average 0.67C between 1982 and 2024, they said.

"If this trend persists, which it likely will, it just means that these animals are going to spend more and more time towards their seasonal distributional limit, which currently is southern and central New South Wales," Lubitz said.

"So it could be that a few decades from now, maybe bull sharks are present year-round in waters off Sydney," he added.

"While the chances of a shark bite, and shark bites in Australia in general, remain low, it just means that people have to be more aware of an increased window of bull shark presence in coastal waters off Sydney."

Climate change could also change breeding patterns, Lubitz said, with early evidence indicating juvenile sharks were appearing in rivers further south.

There was some evidence as well that summer habitats for great whites, which prefer colder waters, were decreasing in northern New South Wales and Queensland, he said.

Tagged sharks trigger an alarm when they swim within range of a network of receivers dotted around parts of the Australian coast, giving people real-time warnings on a mobile app of their presence at key locations.