He is one of the oldest sharks in the world – and at the same time one of the most peaceful: The nurse shark (Ginglymostoma cirratum) is a living fossil whose ancestors populated the seas more than 100 million years ago. Today, it is considered a prime example of an animal group that has barely changed – because it didn't have to.
What is a nurse shark?
Nurse sharks are bottom-dwelling sharks that live in shallow tropical and subtropical coastal waters – especially in the Atlantic and Eastern Pacific. They grow up to 4.3 meters long, are nocturnal, and feed on crustaceans, squid, and small fish. Their name is probably derived from an Old English word for "suck" – because nurse sharks literally suck their prey out of rock crevices.
A Living Fossil
The nurse shark family (Ginglymostomatidae) is ancient. Fossil teeth of similar sharks have been found in layers from the Eocene (approx. 56–34 million years ago) – and the basic form has barely changed since then. This makes nurse shark teeth particularly interesting fossils: they connect the living animal world with a distant past.
Nurse Shark Teeth as Fossils
As with all sharks, teeth are the most commonly preserved remains. Nurse shark teeth are characteristically broad and flat with fine striations – ideal for crushing hard-shelled prey. Fossil specimens from the Eocene show how stable this tooth design has remained over millions of years.
Why Nurse Shark Fossils Are So Special
Nurse shark teeth are rarer than Megalodon or Cretaceous shark teeth – and precisely for this reason, they are coveted by collectors. They represent a lineage of animals that still exists today, offering a direct comparison between fossil and living creatures. A nurse shark tooth is therefore not just a collector's item, but a window into the evolutionary history of sharks.
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