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.
To western palates, and more specifically American palates, this seafood bonanza highlights how limited our diets really are in terms of amount of oceanic phyla consumed. And one group that I want to focus on today which is in no short supply in these Asian markets are cephalopods- the "head-footed" clan of mollusks that includes octopi, squid, nautilus, and cuttlefish. You western readers might be thinking: squid are not so exotic I enjoy a bit of calamari now and again. Yeah, you eat breaded, fried calamari rings- wowee. Go check your cabinet right now- how many cans of squid with ink do you have? How many cans of tuna do you have? Probably a lot more chicken of the sea, no? Us westerners have a very fish biased diet in terms of seafood choice. And it is this fish bias- a certain penchant for backbones - that I want to speak of today. And ultimately discuss how this tendency to look towards all things fishy may actually imbue our interpretation of certain long ago extinct beasties and how they lived.
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
and realizes that these creepy little things ain't anchovies and sucker on to my skin, block my throat, and some even have little switch-blade suckers that draw blood- it is a mistake not soon to be forgotten. And now go back and look at that gif of the unfortunate cat with a face-full of octopus. I was not trying to be cute there but actually trying to illustrate what works and what does not work to be a teuthophage- especially an air breathing one. Just because you can catch and eat fish well does not mean you can catch and eat cephalopods as well. Or you can put it this way: piscivores are not always teuthophages, but teuthophages can always be piscivores. If you are a teuthophage you can tackle tentacled prey in a couple of ways; beaked whales are very much larger than their squid prey and simply inhale their prey whole; sharks, 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.
Mesozoic Calamari
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
doomed ammonite from it's shelly home....
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.
Pterosaur Ptroubles
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.
Rhamphorynchus. wiki |
Snail Kite. Cornell Education |
Anhanguera blittersdorfi. wiki. Ghedoghedo |
Pteranodon. Smokeybjb. wiki |
Matt Martyniuk. wiki |
Belemnite shells |
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.
Duane Nash |
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.
Cheers!!
*thanks to Lloyd Lustina for letting me borrow his phone to capture photos of the ammonites/belemnites at WFVZ collection
Squid Fishing Boats Japan. |
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The alleged Solnhofen squid with tentacles clearly is a fake. At least the tentacles are carved. Also the stone does not look like Solnhofen limestone at all.
ReplyDeleteInteresting, I guess somebody got ripped off because it was sold according to the page I got it from.
ReplyDeleteYeah I see what you mean now when looking at the limestone. And the other fossils sold by this co. look a little suspicious... Oh well serves me right for stealing images haha gonna delete it.
ReplyDeleteAny thoughts on where I can find information on modern teuthophages? I'm trying to figure out what a post global-warming ocean will look like, and if squid, jellyfish, and seagrass are the winners, I'm trying to figure out what will live around them.
ReplyDeleteFor starters there is a nice overview chapter in Richard Ellis' book on giant squid concerning all manner of squidy things. Some of the data on the annual consumption of squid by sperm whales mentioned there is stunning. Beaked whales, pilot whales, bluefin tuna, billfish, penguins, albatross, elephant seals, deep sea sharks are known to eat a lot of squid. I don't know if sound blasts by sperm whales to stun squid is still in favor or controversial... Google southern sleeper shark and colossal squid and you will find some info on that recently revealed teuthophage. Concerning warn/cool waters... squid are important in the Antarctic food web as well which complicates matters a bit as far as cold=fish, warm=squid. And I remember reading red devil squid actually can overheat when foraging in shallow waters so must return to deeper waters...so as so often happens things get more complex the more you look into them.
ReplyDeleteThanks Duane. I'll look into it.
ReplyDeleteHmmm. I checked Ellis' Search for the Giant Squid, and I didn't see much about squid consumption. Did you mean one of his other books, by any chance? Thanks for your help regardless.
ReplyDeleteYeah I seem to remember a chapter on squid- sort of like an overview- with some mention of sperm whale consumption. If you wan to get more technical there are number of books on sperm whales that go into greater depth. I can't think of the names right now but I am sure Amazon list them.
ReplyDeleteThe book Whales, Whaling, and Ocean Ecosystems might have some neat stuff and the late Jurassic Svalbard arctic ecosystems is suggesting a cephalopod dominated system.
Sorry I have never really seen a good single source for teuthophagy/squids- would be a cool book.