Thousands of meters below the sea surface lives the cookiecutter shark (Isistius brasiliensis), a shark barely fifty centimeters long that carries out one of the most unusual hunting strategies in the animal kingdom. Its belly is covered with thousands of photophores that emit a bioluminescent green glow, except for a dark, lightless collar around its neck. Seen from the depths, this dark patch mimics the silhouette of a small, harmless fish, luring colossal predators like tuna, dolphins, and even great white sharks.
When the enormous prey approaches, the cookiecutter shark relentlessly turns the tables. It latches onto the giant's skin using fleshy lips that act as a powerful vacuum suction cup. It then anchors its upper teeth, sinks in its lower row of serrated teeth, and rotates its body in a full 360-degree spin, scooping out a perfect spherical plug of flesh and blubber without killing the host.
The mechanical audacity of its bite is so extreme that during the Cold War it triggered military alarms in the United States Navy:
- In the 1970s, several nuclear-powered submarines returned to base with their neoprene sonar domes and transmission cables shredded.
- Pentagon engineers feared sabotage by a new Soviet secret weapon until marine biologists discovered that the identical circular cuts were caused by the voracious appetite of this tiny shark.
Today, marks from its bites have been documented on nearly every whale species on the planet, proving that in the deep ocean, size does not determine who is the hunter.
Source: Smithsonian Ocean / Biology of Sharks and Their Relatives (Carrier et al., 2012)
