Animals hitch rides together all the time. Sometimes the relationship is mutually beneficial, while in other instances it’s parasitic. Every so often, however, researchers document a previously unknown team-up that is just baffling. That was the case when a team from the University of Auckland in New Zealand noticed a 10-foot-long shortfin mako shark adorned with an unexpected passenger. “What was that orange patch on its head? A buoy? An injury?” marine ecologist Rochelle Constantine recalled in  a university feature. Constantine and colleagues were aboard a nearby ship in the Hauraki Gulf near Kawau Island searching for shark feeding frenzies. Also known as workups, these events are as violent as they are actually uncommon in sharks. Frenzies begin due to a number of factors, but researchers believe a “supernormal stimulus” such as a high amount of stress is what often triggers them. While the arrival of a large mako didn’t necessarily surprise them, they were taken aback by this shark’s mystery “hat.” The team quickly launched a drone from the vessel and lowered a GoPro camera into the water to get a closer look. What they discovered, Constantine said, was “unforgettable.” “We could see these tentacles moving,” she added in a March 20 interview with The New York Times. The shark’s accessory wasn’t inanimate: it was a Maori octopus. Capable of growing up to 6.5 feet wide and weighing around 26 pounds, the Maori octopus is the largest species of its kind in the Southern Hemisphere. The cephalopods range in coloration from an orange-brown to a dark purple-gray, and with a diet that primarily consists of crustaceans and eggs. They are also known for their aggression, particularly when females are protecting their broods of as many as 7,000 eggs. The team-up was made even stranger given what we know about the two animals’ respective habitats. While Maori octopus typically lives along the seabed, shortfin makos only swim to a maximum depth of around 1,000 feet deep. “It makes no sense that these two animals should be at the same place and time to encounter each other,” Constantine said. “We have no idea how they found each other.” The researchers believe that even if the shortfin mako didn’t see the octopus approach it, the shark  almost certainly was aware of its arrival thanks to sensory organs known as lateral lines that cover its body. Alas, the pair’s ultimate fate—or final destination—will remain an unsolved mystery. Constantine and their team allowed the dynamic duo to continue their travels uninterrupted while the group returned to their fieldwork. Given that shortfin makos can reach a top speed of about 46 miles per hour, it’s unlikely the Maori octopus remained on top of it for too long. The team believes that one of two outcomes are likely. Either the octopus drifted 100 to 130 feet down to the ocean floor, or it became a midtrip meal for the mako. Regardless, Constantine explained that their “sharktopus” sighting serves as an excellent “reminder of the wonders of the ocean.” But these and other surprising finds will only continue happening with the proper support of ongoing conservation efforts. The post Shark’s ‘mystery hat’ turns out to be a giant octopus appeared first on Popular Science. ...read more read less