31 October 2013
Decades ago, the film, Jaws, was credited with terrifying movie goers to the point that they avoided beaches for fear of being attacked by a real version of the film’s animatronic great white shark. [image]  Then, there was a sequel with promotional trailers warning: “Just when you thought it was safe to go back in the water.” [image] But at least you were safe on dry land. Right?
Saturday Night Live’s writers decided to take away that last refuge of safety by presenting a predator that could strike on land or sea. In 1975, the first in a series of SNL sketches featured a hapless urban dweller who hears a knock on their front door. When the caller is asked to identify themselves, a voice on the other side of door says “repair man” or “door-to-door salesman.” Then, when the door is opened, in plunges the “Land Shark” (or a giant foam rubber version of the “Land Shark”), which completely consumes the victim.  [image] [video]
Well, the Land Shark was just a joke. Wasn’t it?
It was. But, like more than a few fictional, on-screen characters, the Land Shark seems to have an imitator.
Just when you thought it was safe to go near the water?
Catfish in France have learned to hunt pigeons.   Fishermen on the France’s River Tarn were more than shocked to witness catfish “loitering in shallow water near sandbars populated by pigeons.” When one of the birds wandered too near the water line, it was a “Land Shark” experience for the bird and a meal for the catfish. [video]
When Julien Cucherousset of Paul Sabatier University heard the story from the bewildered fisherman, he captured footage of the “event.” The on-line video went viral. The first time I saw the video, my reaction was almost that of an academic naturalist. “How fascinating,” I thought.
At least, I thought it was fascinating until I learned that these catfish were three to four feet long. So, I am only about 2 feet longer that the largest of these “Land Catfish.” My next thought? Would I . . . ? Yes, I assured myself. I’d win — if caught in a shoreline struggle with an overly aggressive four-foot catfish. Then, I reflected. Suppose I was sick and weak that day? I didn’t try to answer that question. I just . . . thought of something else. 
At first, I was comforted by the fact that this particular species of catfish wasn’t native to France, but had been introduced to the Tarn River about 30 years ago. I imagined some weird, predacious species of catfish from the depths of the Amazonian jungle had been imported and accidentally released into the river. But, when the full story unfolded, it turned out that these were just plain old catfish. And they had been intentionally released into the river. 
Over the last three decades, the waters of the Tarn became less populated with crayfish and other smaller fish. So, the catfish began feeding on land prey — a behavior no member of its species is known to have engaged in before. These fish hover under the water near the shore watching their prospective, terrestrial prey. Then, when an opportune moment presents itself, they leap out of the water onto the dry land, grab their prey, and leap back into the water taking there land-dwelling victim with them. Then, the “Land Catfish” enjoys a leisurely meal in its underwater home. 
Autopsies of the catfish in the area revealed that not all of the fish were eating pigeons. However, those that were tended to abandon their old diet of crayfish and other small fish focusing more exclusively on land prey. 
Somehow, I found the casual way in which these animals extended their hunting range disconcerting. But more disturbing was the autopsy’s suggestion that some fish had developed a taste for land animals — ignoring their old fare of crayfish and other small fish to focus almost entirely on pigeons. As a land-based mammal who enjoys strolling along the shores of natural bodies of water, I’m still not entirely comfortable with these developments.
One writer, attempting to minimize the strangeness of it all, noted that African crocodiles jump out of the water and grab zebras. And whales beach themselves on the ice to nab penguins for dinner. But these are hardly apt comparisons. Crocks and alligators are air-breathing lizards. They just hang-out in the water. Whales are also air-breathing mammals who have adopted a fish-like lifestyle. 
Neither of these examples could compare to a plain old fish intentionally jumping out of the water to grab some terrestrial creature, drag it into the water, and eat it. I’ve watched scenes like this in old horror movies. I’ve always loved to stroll along the shore of almost any waterway, but is it safe? Where I live, my favorite body of water is the Mississippi River. After seeing this video, I checked. The Mississippi is teaming with catfish – those same enterprising, opportunistic, and hungry sea-beasts that are scarfing down pigeons in France!
On calmer reflection, I realized that the Land Catfish is actually engaged in the mirror image of human sea diving. Somehow, I’d always thought that land creatures dived into the water to feed on unsuspecting sea creatures. Not the other way around. And human beings had the distinction of being the only creature that could learn to dive into the water for food (and maybe a few pearls). Now, the Land Catfish has turned the tables on us.
But the Land Catfish isn’t the only sea creature that feels free to promenade out onto the dry land to pick up a meal.
A few decades ago, I remember strolling along a Sarasota beach at midnight — my feet kicking through the white sand. In those distant days, you could still find yourself quite alone on the beach at night. Absolutely taken with the beauty of the Gulf, I remember thinking how nice it would be to just stretch out on the sand and sleep in the cool breeze off the water until sunrise.
All those years ago, I would still have been quite safe from human interference, but I would never have thought of the possibility of something coming up out of the sea. I can imagine the psychological trauma I would have experienced if, in the middle of that peaceful night’s sleep, I had stirred awake and opened my eyes to see an eye looking back at me: the “dominant eye” of a local octopus. The creature wouldn’t have been interested in me. It would have just been “passing by.” But, after an experience like that, I would have moved to the top of a mountain — as far away from the water’s edge as I could get.
Not long after I saw the “Land Catfish” video, a story broke about a “Land Octopus.” The terrestrial excursions of the octopuses have stayed pretty much out of the public eye until recently when one of these strange creatures was caught in the act – on video. [video] An octopus was seen grabbing lunch, not while roaming where it belongs – underwater — but, instead, crawling around on the beach casually grabbing a few snacks. The witnesses got a video camera and the rest is internet history. 
How long has this sort of thing been going on, I wondered? Well, octopuses have been doing this since . . . forever.
The Land Octopus starring in the San Mateo County, California video was not engaged in any particularly unusual behavior. Marine biologist James Wood explained that several species of octopuses make brief forays onto land for a meal.  Most discomforting was his explanation of why the public is so ignorant of this particular octopus behavior. Octopuses leave the water all the time. They just do it when they won’t be seen. Wood explained that most octopuses are nocturnal, sneaking out of the water at night to enjoy their meals unobserved.  Well, with this factoid, my nocturnal seashore walks are over.
The octopus caught on video was probably engaged in the octopus version of grocery shopping. Julian Finn, a senior curator of marine invertebrates at the Museum Victoria in Australia explained that octopuses frequently emerge and hunt in tidal pools when the tidal waters recede. The octopus examines these “grocery shelves” either with its eyes, (octopuses have rather good vision), or feel for food with its outstretched arms (tentacles?). 
However, not so typically, the cephalopod shopper in this video is seen discarding an empty crab shell during its shopping spree — after eating the occupant. Either this octopus was particularly hungry and couldn’t wait to get home, with the crab serving as a kind of fast food snack or, even with eight arms, carrying all those groceries got to be too taxing. If the “groceries” get too heavy, octopuses often stop and eat their way to a lighter load. 
However, shopping isn’t the only thing that brings octopuses out of the water and onto dry land. Finn explained that octopuses also “lurch” out of the water onto land to escape danger. Wood recalled an incident in which he was chasing and photographing a common octopus “when it crawled out of the water, across eight feet of rocks and went back into the water” apparently hoping this maneuver would confuse the pursuing photographer. 
Mercifully, octopuses aren’t interested in eating people. Hostile interactions between octopuses and people happen when the octopus perceives a person as a threat rather than as a potential meal.
Still, even if I’m not on the menu, I wouldn’t like to encounter an octopus as I was strolling or resting on dry land. Imagine if I’d paused to catch my breath on that eight foot expanse of rocks when the Land Octopus jumped out of the water in its attempt to shake the pursuing James Wood. After literally running into an octopus on dry land, you can bet that it would be a long time before I thought it was safe to go anywhere near the water.
Mark Grossmann of Hazelwood, Missouri & Belleville, Illinois
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