5 weird & wonderful sharks (and fast facts about them)

The strange (and sharp!) teeth of a cookie cutter shark. Perfect for cutting cookie-shaped chunks of flesh from dolphins, just like Grandma used to make. Photo: Flickr/JSUBiology

#1 Cookie Cutter Sharks (Genus: Isistius)
Distribution: Unclear due to lack of data.
Status: Least Concern

Using sharp teeth and a spinning motion, cookie cutters are able to rip out perfectly circular chunks of flesh from prey before retreating back into the deep sea.

They may be small (max. length 54cm), but cookie cutters are able to prey on cetaceans – 49 species have been recorded with circular scars from their attacks.

It’s believed cookie cutters may mimic squid to lure cetaceans close, a strategy so successful, one study found almost 100% of spinner dolphins in Hawaii sported circular scars from cookie cutter attacks.

Finally, not ones to be wasteful, cookie cutter sharks will swallow their old teeth for extra calcium!

Analysis of Greenland shark eye lenses has revealed they’re the longest living vertebrate on the planet! Photo: Flickr/NOAA Photo Library

#2 The Greenland Shark (Somniosus microcephalus)
Distribution: North Atlantic
Status: Near Threatened

The largest fish in arctic waters, the Greenland shark lurks in cold depths and grows up to 5m. What’s most mysterious about this shark species however, is how long it lives for.

The Greenland shark may just be the longest lived vertebrate on the planet, with one study ageing a specimen at just under 400 years old! 

As sharks are largely made of cartilage and therefore lack calcified tissues (like bone), radiocarbon dating was conducted on Greenland shark eye lenses to test their age.

A wriggly, wonder shark! Epaulette sharks can walk out of the water and across coral when the tide rolls out. Photo: Used with permission from Jodie Rummer

#3 The Epaulette Shark (Hemiscyllium ocellatum)
Distribution: Australasia
Status: Least Concern

Epaulette sharks don’t just swim, they can walk! When the tide rolls out, stranding them on the coral flats they frequent, they use their fins instead to walk around.

Walking out of the water means epaulette sharks are also extremely tolerant to a lack of oxygen. Experiments show they can go for 3.5hrs in these low O2 conditions!

Go on, count ’em. The broadnose sevengill shark has seven gills. They’ll also hunt in packs to take down large prey. Photo: Flickr/Derek Keats

#4 Broadnose sevengill shark (Notorynchus cepedianus)
Distribution: Most temperate waters
Status: Data deficient

While most sharks have five gill slits, sevengill sharks appropriately have seven. It’s the greatest number of gill slits of any shark (equalled only by the sharpnose sevengill shark)!

Despite a smallish size (around 3m) some specialised hunting tactics mean sevengill sharks are also capable of catching large, fast-swimming prey – such as dolphins and fur seals.

They achieve this by working in packs! Together they’ll create a loose circle around their target and rush in with attacking blows.

What a mug. The incredibly strange goblin shark has a jaw that shoots out of its face at prey. Photo: Dianne Bray/Museum Victoria

#5 The Goblin Shark (Mitsukurina owstoni)
Distribution: Atlantic, Indian and Pacific Oceans
Status: Least Concern

Now THAT’s a face. You’ll instantly spot a goblin shark in a line up, thanks to their distinctively flat, blade-like snout and soft, flabby bod.

Perhaps most surprising about these deep water weirdos however – is their jaw. It physically shoots out of their face at prey, just like a slingshot. Definitely check it out in action here.

And that’s a wrap! Let me know your favourite weird shark species in the comments below and share this post to spread some shark love.

References

Dwyer, S. L., & Visser, I. N. (2011). Cookie cutter shark (Isistius sp.) bites on cetaceans, with particular reference to killer whales (orca)(Orcinus orca). Aquatic Mammals, 37(2), 111.

Heithaus, M. R. (2001). Predator–prey and competitive interactions between sharks (order Selachii) and dolphins (suborder Odontoceti): a review. Journal of Zoology, 253(01), 53-68.

Hickey, A. J., Renshaw, G. M., Speers-Roesch, B., Richards, J. G., Wang, Y., Farrell, A. P., & Brauner, C. J. (2012). A radical approach to beating hypoxia: depressed free radical release from heart fibres of the hypoxia-tolerant epaulette shark (Hemiscyllum ocellatum). Journal of Comparative Physiology B, 182(1), 91-100.

Nielsen, J., Hedeholm, R. B., Heinemeier, J., Bushnell, P. G., Christiansen, J. S., Olsen, J., … & Steffensen, J. F. (2016). Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science, 353(6300), 702-704.

Yano, K., Miya, M., Aizawa, M., & Noichi, T. (2007). Some aspects of the biology of the goblin shark, Mitsukurina owstoni, collected from the Tokyo Submarine Canyon and adjacent waters, Japan. Ichthyological Research, 54(4), 388-398.