Great white sharks have long been hailed the silent stalkers of the expansive sea, their reputation that of vicious and successful predators.
However, what if I were to tell you that their food of choice has decided to fight back? In a twist on the phrase 'monsters vs. aliens,' it has been observed that alien-like squid take on monstrous white sharks. And not only do they survive, but they leave calling cards of their victory on the shark's bodies.
Picture taken from the research paper, the triangles indicate the scars left from interaction with the squid.
The Battle Between Predator and Prey
Sharks are common predators of squid, making up to 98 percent of the diet in blue and hammerhead sharks. In particular, white sharks are natural predators of squids and other members of the cephalopod family, including cuttlefish. Their low levels of fat and high protein levels make them an ideal snack, easily digestible, and provide essential nutrients for the shark's reproduction. Predator-prey interactions between sharks and squids have long been documented across the world's ocean and are considered fundamental to preserving marine food webs and the success of marine habitats.
Great white sharks are seasonal migrators. Between February to July, these iconic species travel to an area known as the Shared Offshore Foraging Area (SOFA) in and around the waters of Guadalupe Island. Guadalupe Island is home to an array of marine life, including many seabirds, seals and sharks. Here, they take advantage of the plentiful abundance of food from tuna, bass, and, you guessed it, squid.
It is important to remember the sheer size differences between these sea dwellers. Female great white sharks can grow up to a colossal 20ft, and males, being smaller, residing between 11 to 13ft. On the other hand, the jumbo squid (also known as the Humboldt squid) only grows to around 4ft.
Historically, large quantities of jumbo squid have been found in the stomachs of white sharks. But now, it is clear that the squid are fighting back.
Visible Scars and Signs of Interactions
In a study led by Dr. Becerril-García at the Interdisciplinary Center of Marine Sciences of the National Polytechnic Institute (Mexico), researchers studied interactions between the white sharks and squid. The team tagged and monitored white sharks around Guadalupe Island using underwater photographs to identify sharks and measure the scars on their bodies. The scars on the shark's bodies were attributed to interactions (fights) with jumbo squid.
Researchers saw distinct sucker marks left by the squid on the shark's head and trunks. The suckers were thought to be that of the jumbo squid and evidence of fights between them.
These squids had been somewhat successful at evading becoming lunch as some sharks had multiple scars over the top of one another, indicating regular fights. Quite literally, the squid's defenses are so ferocious that their suction power deforms the shark's skin and can even cause open wounds - not bad for an animal that doesn't have any bones.
The ferocity of squids extends to other predators and has been observed to fight their corner with another, even larger predator, sperm whales.
This study also speculated on the wider implications of their findings. Squid and sharks are members of ancient lineages that have existed for over 450 million years, preceding humans by over 400 million years. This means that research in this area may reveal important aspects of their evolution and the process whereby matter (food) is exchanged as energy throughout marine ecosystems around the world.
If there ever were a metaphor for not taking something lying down, it would be that of the jumbo squid rejecting its place in the food web as prey. Its ferocious and heroic act of taking on much larger predators and living to tell the tale is almost mythical and comparable to the folklore of sailors fighting off sea monsters of the deep.
By Kaya Taylor
This article was based on the following research paper: Becerril-García, E.E., Bernot-Simon, D., Arellano-Martínez, M. et al. Evidence of interactions between white sharks and large squids in Guadalupe Island, Mexico. Sci Rep 10, 17158 (2020). https://doi.org/10.1038/s41598-020-74294-4
