Fun facts about basking sharks

March 29, 2024

Second only to the whale shark, this huge but placid creature is the world’s second largest fish. It got its name from the fact that it looks like it's basking in the sun when it cruises near the surface (it's actually feeding on plankton in these shallow waters). We now know they routinely dive to 3,000 feet and researchers have even tracked basking sharks almost a mile deep. Its scientific name, Cetorhinus maximus, means something like ‘great-nosed sea monster’ in Greek, which is quite a good description of the bulbous face. Here are a few of my favourite facts about these less-than-monstrous sea monsters.

Fun facts

  • We recently discovered that basking sharks are regional endotherms (aka warm blooded). I wrote about the paper for New Scientist - so fun to learn about.
  • Since breaching uses much more energy than swimming, there must be a good reason why basking sharks are the biggest sharks that can breach. They can jump entirely out of the water, often several times. But we haven’t much clue why they do it. It could be a technique to dislodge parasites or they're showing off to potential mates.
  • We used to think that basking sharks hibernated but that’s not true. They are rarely seen in UK waters in winter because they head for deeper waters of the continental shelf and more distant waters around Spain, Morocco and the Faroe Islands. This may be to mate or to feed – we don’t really know (yet).
  • At a lazy speed of just two miles an hour, basking sharks can filter around 2,000 tons of seawater an hour.
  • The basking shark’s mouth is three feet wide and has six rows of teeth in its upper jaw, and nine rows on the bottom jaw, giving a total of 1,500 tiny, hooked teeth. However, these filter-feeders use their teeth on their friends rather than their enemies – as we can deduce from scars on the backs of female sharks! 
  • The UK’s only fatal shark encounter was recorded in 1937 when a breaching basking shark unintentionally capsized a boat. The three people on board perished.
  • A basking shark female is pregnant for up to three and a half years. We don’t know a lot about the process but in 1943 in the seas off Norway, a female gave birth to five live pups and one stillborn. All the pups measured between 4.5 and 6.5 feet.

Scary facts

Basking sharks are under threat. They were put on the endangered list in the 1990s in response to collapsing population numbers. This was because of overfishing not just for their meat and skins but also for their liver oil. This oil was widely used in lamps, cosmetics, perfumes and lubricants. Their small number of young also contributes to their vulnerability. Thankfully, basking sharks are one of the most highly protected sharks in European waters. Hopefully conservation measures can help their populations recover.

How you can help

  • Ingesting harmful microplastics is a risk factor for all zooplankton-eating species. That's why supporting any efforts to drastically reduce plastic waste will be a benefit to these wonderful fish.
  • Climate change can have a detrimental effect on the food basking sharks eat (and so threaten the sharks themselves). So, taking steps to become more sustainable is a good way to help basking sharks and the wider marine ecosystem

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