COOKIECUTTER SHARKS: BEASTLY LITTLE SUCKERS


Cookiecutter Shark mouth, jaws & teeth (BMMRO Bahamas)

COOKIECUTTER SHARKS

BEASTLY LITTLE SUCKERS

The Cookiecutter shark Isistius brasiliensis (aka the less scary, more genial sounding ‘cigar shark’), might be an ideal candidate for a Room 101 nemesis.** These little beasts – a species of dogfish shark – are found in several mainly island-based areas dotted around the globe, including in Abaco waters.

 

HOW COME THE NAME?
These sharky little b@st@rds (*technical term*) attack marine mammals and fishes, gouging out perfect round plugs of skin and flesh, leaving what are sometimes called ‘crater wounds’. Then they eat them. Imagine getting hold of a really sharp domestic cookie cutter with circular rows of razor-sharp teeth, and grinding it hard into your thigh. There! That! 
The size of an adult shark:16″ max
The term ‘cookiecutter’ is also a pejorative slang term, meaning mass-produced, lacking in originality, or boringly samey, as in cookiecutter cars or TV genres etc. The little critters under consideration here are anything but…
                        

HORRIFYING COOKIECUTTER FACTS

  • Live in the depths, rise vertically in the day & dive back down at dusk
  • Undersides have light-emitting ‘photophores’ which emphasise…
  • …the dark collar which acts as a lure, resembling a small innocent fish
  • Bioluminescence lures prey & confuses predators (more on this below)
  • The glow is so strong it may last for some time after removal from water

  • Their lips are ‘suctorial’ = they attach tightly to their target
  • The jaws then gouge out the victim’s flesh in a remarkably neat circle
  • Omni-vicious: any medium to large ocean creature is vulnerable to attack
  • There are even occasional reports of humans being targeted

Here are two Blainville’s beaked whales that I photographed from the BMMRO research vessel. The top whale has a number of circular healed attack marks and a recent one. You can see how deep the gouged hole is. The other has well-healed scars.

Blainville's Beaked Whale - cookiecutter shark damage (Keith Salvesen)Blainville's Beaked Whale - cookiecutter shark damage (Keith Salvesen)

  • Multi-toothed: top rows of small teeth, rows of larger teeth on the bottom
  • The lower teeth are the cutters, acting like a saw when locked on
  • See header image and below for full details

    

HOW EXACTLY DO THEY DO WHAT DO THEY DO?
I can explain it no better than the renowned authority Prof. W. K. P. Dear:  “the suctorial lips ensure a tight seal. It then bites, using its narrow upper teeth as anchors while its razor sharp lower teeth slices into the prey. Finally, the shark twists and rotates its body to complete a circular cut, quite possibly aided by the initial forward momentum and subsequent struggles of its prey. The action of the lower teeth may also be assisted by back-and-forth vibrations of the jaw, a mechanism akin to that of an electric carving knife”.

                 ARE THESE SHARKS ‘PARASITES’, WOULD YOU SAY?

The behaviour of these sharks is an example of a symbiotic relationship between two species that is parasitic. This means essentially that one gains and the other suffers (e.g. no-see-ums!). This is distinct from commensalistic symbiosis, where one species gains and the other is unaffected (e.g. cattle egrets with cattle); and mutualistic symbiosis, where both gain (e.g. cleaner fish & groupers). So, in a word, yes.

  • An ‘ambush predator’: they ‘hover’ in the water column waiting…
  • They are capable of rapid movement to catch up & latch onto prey
  • They will eat a passing small fish, crustacean or even squid as a snack
  • Sometimes they operate in schools; there is safety in numbers
  • The schools are thought to increase the ‘lure’ effect of the dark collar

A beached whale that’s been heavily targeted

FUN FACT TO COUNTERACT THE BAD STUFF

In the late c20, more than 30 U.S. Navy submarines were forced back to base to repair damage caused by cookiecutter shark bites, either to the neoprene footings of sonar domes or to rubber-sheathed cables. The problems were solved by using fibreglass. Oceanographic equipment and telecommunications cables are also recorded as being damaged by these sharks.

Cookiecutter Shark – the real deal

 

MONSTERS OF THE DEEP

These great cards from the weirdly spelled WIERD ‘N’ WILD CREATURES provide excellent factual info. Their CCS card is no exception. You’ll find more details here about the effect of the bioluminescence and so on, written as clearly as I might hope to. 

Cookiecutter Shark Facts (Monsters of the Deep)Cookiecutter Shark Facts (Monsters of the Deep)

** “The worst thing in the world varies from individual to individual. It may be burial alive or death by fire, or by drowning, or by impalement, or fifty other deaths. There are cases where it is some quite trivial thing, not even fatal.” (George Orwell, 1984)

Alright now…Blainville's Beaked Whale - cookiecutter shark damage (Keith Salvesen)

Credits: BMMRO – header image; beaked whale photos – Keith Salvesen / BMMRO; Te Ara NZ for the main jaw image; all small images with thanks to Wiki and respective photographers who took the time to upload them for all to enjoy & learn from; ‘wierdnwonderful creatures’ for the monster card; range map from Wiki

PS Apologies to anyone who bothered to wade through this, and stayed awake long enough to notice that formatting gremlins struck halfway through

3 thoughts on “COOKIECUTTER SHARKS: BEASTLY LITTLE SUCKERS

  1. Pingback: Small sharks eating great white sharks | Dear Kitty. Some blog

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