This week’s Featured Species is a small shark that packs a nasty punch. The cookiecutter shark (Isistius brasiliensis), or as it was once known as the cigar shark for its small, cigar shaped body. The cookiecutter shark only reaches a maximum length of 1.6 feet (.48 m), it is far from the smallest shark in the world. That title belongs to the Dwarf Lantern Shark (Etmopterus perryi) at a mere 0.55 feet, or 6.6 inches or 17.02cm (Fricke, & Koch, 1990)!
Despite it’s relatively small size, the cookiecutter shark packs an incredible bite. The upper and lower jaws featured a very different set of teeth! The upper jaw (pictured below on the bottom) are small, narrow, and tapper to a single point. The lower jaw (pictured below on the top) are larger, more broad and knife-life (Compagno, 2001). These sharks also shed their teeth in an unusual way. The top teeth are shed individually, like traditional shark teeth; however the bottom teeth are not. These teeth are actually shed an entire row at a time (Strasburg, 1963)! The cookiecutter shark actually swallows this entire row of teeth, recycling the calcium content, possibly to help balance the significant resource investment made by replacing an entire row of teeth at the same time (Starsburg, 1963).
Aside from a unique set of jaws, the cookiecutter shark also has a unique way of feeding. Cookiecutters are parasitic. They uses their rubber-like lips to suction themselves to their prey, often marine mammals or other large oceanic fishes. Then it sinks its sharp upper jaw into its prey to secure a hold. The cookiecutter shark then rotates its body around in a circle while the lower jaw slices down into its prey’s flesh. Finally the shark detaches with an entire plug of flesh (Skomal, 2016).
But how do these large marine mammals and oceanic fishes not see the cookiecutter shark approaching? Couldn’t they just swim away? After all they are several times larger than the cookiecutter, surely they are capable of escaping such a nasty wound. The cookiecutter has a really cool trick: photophores (Parker, 2008). Photophores are light producing organs that are scattered all across the underside of the cookiecutter shark’s body. These bioluminescent organs allow for the cookiecutter to blend into the bright light coming from the surface above when viewed from below, making the shark nearly invisible (Parker, 2008). That’s a pretty neat trick in my book! In fact they are one of the “brightest” sharks known to science (Parker, 2008).
BBCWorldWide. (2008, August 12). BBC: Perfect Shark- Cookie Cutter Shark [Video Clip]. Retrieved from https://www.youtube.com/
I’m delighted to announce a partnership with the wonderfully talented Julius Csotonyi! Julius creates stunning shark coloring sheets that are fun and educational for all ages. From time to time you’ll see Julius’ work featured right here and on my other social media platforms! You can find more coloring sheets in the store! You are welcomed to download these beautiful sheets and enjoy them with family and friends.
Authority: Quoy & Gaimard, 1824
Family: Dalatiidae (kitefin sharks)
Length: 1.6 ft (0.48 m) maximum
Habitat: Oceanic deepsea
Depth: Over 11,000 feet (3350 m)
Litter Range: 6 – 12 pups
Home Range: Patchy worldwide distribution in tropical waters
Diet: Deepwater fishes and squid; parasitic on other fishes and marine mammals
IUCN Status: Least Concern; rarely encountered by fisheries
(Skomal, 2016; Stevens, 2003)
Thanks for checking out one of the weirdest, and some what creepy, sharks in this week’s Featured Species series. If you missed last week, be sure to check out the Basking Shark. Let me know what you’d be interested in seeing in future posts! I’d love to know what species or subjects you want to know more about. Comments welcome!
The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!
Remember you can make a difference for marine ecosystems by calling your Congress man or woman and tell them that you care about the quality of our waters! Sharks, rays, and other marine organisms cannot speak or be represented in Congress. They need your voice. Get involved and stand up for sharks. Until next time finatics.
Featured Image Source
Zugaro, R. (Photographer). (2017 June). A Smalltooth Cookiecutter Shark, Isistius brasiliensis, from off southern Queensland [Digital Image]. Retrieved from http://fishesofaustralia.net.au/
Compagno, L. J. (2001). Sharks of the world: an annotated and illustrated catalogue of shark species known to date (Vol. 1). Food & Agriculture Org..
Fricke, R., & Koch, I. (1990). A new species of the lantern shark genus Etmopterus from Southern Africa (Elasmobranchii: Squalidae). Stuttgarter Beitr. zur Naturkunde. Ser. A, Biologie.
Parker, S. (2008). The encyclopedia of sharks (2nd ed.). Buffalo, NY: Firefly Books Ltd.
Skomal, G. (2016). The Shark Handbook: The Essential Guide for Understanding the Sharks of the World. (2nd ed.). Kennebunkport, ME: Cider Mill Press.
Stevens, J. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Isistius brasiliensis. The IUCN Red List of Threatened Species 2003: e.T41830A10575586.
Strasburg, D. W. (1963). The diet and dentition of Isistius brasiliensis, with remarks on tooth replacement in other sharks. Copeia, 33-40.
Tricas, T. C., Deacon, K., Last, P., McCosker, J. E., Walker, T. I., & Taylor, L. (1997). The Nature Company Guides: Sharks and Rays. (L. Taylor, Ed.). Hong Kong: The Nature Company, Time Life Books.