Much of this post was inspired by a discussion I had in the comments over at Jaime Headen's heady blog the bite stuff about Rhamphorynchus muensteri.
When I lived in the Bay Area one of my favorite past times was exploring Asian food markets. Not so much to shop for food (though they often had killer deals on beer) but just to get a kick out of the seafood selection. Seriously, the amount and sheer variety of oceanic critters on display at these places is astounding- kind of like going to an aquarium without feeling guilty over the imprisoned killer whales. All sorts of fish, cute little dried sea horses on sticks, crustaceans, molluscs- hell even dried jellyfish snacks (or jellies if you want to be PC)- were there either canned, dried, salted, butchered or even alive.
|Humboldt Squid. Bill Erhardt (c). Baja CA 2008|
Never the less if we paint with very broad strokes cephalopods seem to be winning in warm, oxygen deprived waters. I am looking at you Mesozoic oceans. Indeed in Mesozoic oceans we have not only squid, including big ones, but ammonites and belemnites. A very tentacle ridden, cult of Ctulhu styled scuba dive you might have if you explored the Western Interior Sea. Not only were cephalopods abundant and diverse but the work of the Jurassic Spitsbergen Research Group shows that fish were ecologically insignificant in some Mesozoic oceans. If you don't know now you know, calamari in form or another was a common food for aquatic predators during the Mesozoic.
Do Brown Pelicans Avoid Squid... and if so Why?
Whenever I get a chance I love to talk to fishermen to glean any kind of info I can from them. Now we all know what they say about fisherman's tales but sometimes they will give you some info that perks your interest. And one of the more interesting bits I have heard on several occasions is that brown pelicans, Pelecanus occidentalis, assiduously avoids squids. And where I live on the coast of California this struck me as a bit odd because we are having record hauls of market squid, which form huge shoals, and pelicans are ubiquitous here. Maybe these admittedly anecdotal accounts speak to a larger truth -why avoid such a tasty nutritious treat? As the you tube video above suggests maybe pelicans are not so dissimilar to humans when it comes to food. If you have a bad experience with a certain food type you are not apt to repeat that same mistake. And when a plunge diving pelican gets a beakfull of squid in it's gular pouch
pinnipeds, and predatory fish have the dental equipment/bills to dismember squidy prey on the spot negating the tentacled counterattack; sea birds that eat squid have longer bills, sometimes have ridged tongues for killing. Something like Pelagornis comes to mind when imagining the penultimate avian teuthophage. Ultimately when the cephalopod and the teuthophage are more equally matched in size- the would be predator wants to have a long, sharp mandible to keep Mr. Squiggly at arms length. And this is double important when the teuthophage in question is an air-breathing tetrapod.
Now with the perils and pitfalls of teuthophagy in mind let us revisit the Mesozoic and remind ourselves that not only were there often abundant squid, but also shelled ammonites/belemnites. And given that many ammonites may have indeed been plankton consumers and were so common that their fossils constitute index fossils I want to pay special attention to them. Predation scores left on the shells of ammonites are well known, mosasaurs usually indicted as the culprit. And it is not too hard to imagine the heavy maw of a mosasaur, pliosaur, robust snouted icthyosaur or sea-going croc having a go at these shelled delicacies.
Does this imply the more daintier snouted icthyosaurs, plesiosaurs, elasmosaurs, and other more slender snouted/toothed marine predators simply left ammonites alone? I would argue no- they simply had other ways to retrieve the flesh and leave the shell alone. A quick snap at an exposed tentacle by any one of these critters at an ammonite. Establish a good grip. And then the predator can either shake off a piece, or... ready for this... go into a death roll pulling off a tentacle or maybe even yanking out the whole squishy body. And I know you love death rolls, now just imagine a 14 meter Elasmosaurus, grabbing onto the fleshy part of a large ammonite, and spinning on it's own axis with a two tonne body creating tremendous torque funnelled down that long neck yanking the
I once saw a documentary on Moray eels and a similar death spin tactic was used by the eel to rip off a tentacle from a much larger octopus.
Now keep in mind that I am not suggesting fish and other critters were not routinely consumed by marine reptiles. The fossil evidence of stomach contents, coprolites tells us specifically that fish, turtles, pterosaurs and even benthic invertebrates were common dinner fare for some of these guys. In fact for the record, all things being equal, I automatically assume a generalist diet for just about any predator- especially marine reptiles. For me proving an obligate specialist diet requires more of a burden of proof than a more opportunistic/generalist strategy. What I am suggesting is that where we have an abundant prey base of shelled cephalopods- we should expect predators on hand to consume them and start looking for ways that they accessed such prey.
But it is also worth mentioning that fish remains have a better preservational potential in coprolites/gut remains than cephalopods because, you know, skeletons. And this bias would be even more pronounced if predators were just ripping off chunks and isolated tentacles from cephalopods.
As many have learned to their peril, putting forth thoughts on pterosaurs on the interwebz is a touchy subject. But since it was a discussion of Rhamphorynchus that started this whole train of thought here we go.
|Snail Kite. Cornell Education|
|Anhanguera blittersdorfi. wiki. Ghedoghedo|
|Pteranodon. Smokeybjb. wiki|
|Matt Martyniuk. wiki|
And with the commencement of this strange and scary nightwatch an aerial division also ramped up it's activities as well. An old Pteranodon sternbergi had reached a size and level of experience that distinguished it from younger and smaller pteranodons. He no longer squabbled with flocks of ocean birds and smaller pteranodons over small bait-fish balls and cephalopods but sought bigger fare- the largest cephalopods the ocean had to offer in fact. And he secured great big calamari steaks not by killing them himself (although he did sometimes dispatch disabled and wounded cephalopods he found on the surface) but by following pods of mosasaurs. And in a manner foreshadowing fellow long distance ocean travelers such oceanic white tips following pilot whales and albatross following killer whales the old Pteranodon hooked up with a pod of Tylosaurus kansasensis which the big pterosaur would follow for weeks at time for food.
|Albatross Encounter. NZ. Sperm whale leftovers.|
|Sakamoto, Takahashi, Trathan. wiki. Albatross & killer Whales|
Sometimes scraps and chunks of ammonite would float up to the surface or sometimes the mosasaurs would drive to the surface a big boil of ammonites- but what the Pteranodon really relished was when a mosasaur would surface after a deep dive with a big ammonite. The ammonite, either dead or nearly dead, would float to the surface because of the gas filled chambers in it's shell.
At this point, with the mosasaur replenishing it's oxygen after the long dive, the Pteranodon had unmitigated access to the carcass. Perhaps grab a tentacle and flap vigorously to dismember it, or if the mantle is open start probing into it with the long, sharp beak for choice bits of reproductive organelles, eggs, and other viscera.
Above I have depicted such an event. A wounded, slowly dying large ammonite has been pulled up from the depths by a mosasaur. The mosasaur, recuperating from the dive and struggle, is in the background to the right. Seizing the opportunity a Pteranodon has swooped in to pull off a tentacle.
*thanks to Lloyd Lustina for letting me borrow his phone to capture photos of the ammonites/belemnites at WFVZ collection
|Squid Fishing Boats Japan.|