On October 6, 1941, just a few months before the United States entered World War II, the SS Thistlegorm was bombed by two German aircraft while moored at Safe Anchorage F in the Gulf of Suez. An armed British merchant ship staffed with both sailors and Royal Navy gunmen, the vessel had been en route to deliver Wellington boots, armored vehicles, and other supplies to Allied troops in Egypt when the bombers struck. The aircraft hit their target twice, killing nine men and sending the Thistlegorm to rest 30 meters (100 feet) below the ocean’s surface. There, over time, the ship’s anti-aircraft guns became encrusted with soft corals, its Bedford trucks became hideouts for moray eels and squirrelfish, and its top deck became a prime platform from which expertly camouflaged crocodilefish and scorpionfish could launch ambush attacks. Additionally, as photographer Alex Tattersall beautifully documented during a 2013 dive, common lionfish (Pterois miles) began haunting the wreck to hunt the vast schools of silversides and cardinalfish that sought refuge in the ship’s holds.

The fate of the Thistlegorm may have been different had its planned passage through the Suez Canal and expected September arrival in Alexandria not been foiled by a collision that clogged the canal’s shipping lanes. Common lionfish, on the other hand, have had no trouble navigating the manmade channels of the Suez to reach the Mediterranean Sea. Scientists first documented the species in the Mediterranean in 2012, and they have since watched the fish proliferate quickly—an unsurprising development given the highly successful invasion of lionfish in the Atlantic.

A 2017 study led by scientists at the American University of Beirut confirmed through genetic testing that the lionfish now resident in the Mediterranean arrived via the Suez Canal. Their invasion is yet another example of what scientists call a Lessepian migration—passage of marine species through the Suez Canal, usually from the Red Sea into the Mediterranean (named in dubious honor of Ferdinand de Lesseps, the French diplomat in charge of canal construction). Although these invasions have occurred for nearly 150 years, Lessepian migrations are now becoming more common because of global climate change. “A hundred years ago, it used to be too cold for most reef fishes in the Mediterranean,” says California Academy of Sciences ichthyologist Luiz Rocha. “But not anymore.”

While the lionfish are an unwelcome sight in the Mediterranean, here on the Thistlegorm, where they patrol their native territory, divers like Tattersall can watch these skilled predators work with nothing but awe and appreciation.