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Longtime readers of this blog probably think that my favorite order of fish are the catfish (siluriformes), a vast order of fascinating freshwater fish which have based their success on mastering sensory perception, or possibly the flatfish (pleuronectiformes) whose predator/prey dichotomy and tragicomic frowns are featured heavily in my elegiac artwork about the decline of the oceans. Readers who have really read closely might suspect the lungfish or the ghost knife fish. Yet, actually, I haven’t written a great deal about my personal favorite order of fishes because they are so eclectic and eccentric that they are hard to write about. The Tetraodontiformes are an ancient order of teleosts (rayfin fish) which apparently originated on the reefs of the mid to late Cretaceous (during the age of dinosaurs). There are currently 10 extant families in the order, but the Tetradontiformes are not closely related to other bony fish.
So what are these ten families of exciting weirdo fish? Wikipedia lists them alphabetically for us!
- Aracanidae — deepwater boxfishes
- Balistidae — triggerfishes
- Diodontidae — porcupinefishes
- Molidae — ocean sunfishes
- Monacanthidae — filefishes
- Ostraciidae — boxfishes
- Tetraodontidae — pufferfishes
- Triacanthidae — triplespines
- Triacanthodidae — spikefishes
- Triodontidae — Threetooth puffer
Triggerfish, pufferfish, boxfish, filefish, cowfish, enormous weird sunfish…there is such a realm of wonder, beauty, and ichthyological fascination among these groups that it is hard to know where to start (although the Mola mola, which I have written about, is a pretty good headliner). The intelligent, colorful, and truculent triggerfish (Balistidae), in particular, are the source of endless delight.
I will write more about all of these in turn, but, before we get into that, it is worth highlighting some shared features of the Tetraodontiformes. These fish tend to have extremely rigid bodies which means they move differently from the quicksilver darting which other fish employ. They rely on fluttering their pectoral, dorsal, anal, and caudal fins to move (comparatively) slowly, albeit with extreme precision. Most Tetraodontiformes are masters of armor or other defensive mechanisms (toxins, spines, pop-up bone locks, and, um, self-inflation). Because of their tropical reef lifestyle and the nature of their defenses these fish often tend to be extraordinarily colorful.
Now is not the time to get into the details of all of these fish. Today’s post is mostly a teaser of things to come…but believe me, it will be worth it. The Tetraodontiformes are truly astonishing. Their colors and patterns do not just put most artists to shame, they put most 1980s artists to shame. And their vivid beauty and astonishing appearance isn’t even the most amazing thing about them. Stay tuned!
Let’s look back through the mists of time to peak at one of the most mysterious and perplexing of mammals, the desmostylians, the only extinct order of marine mammals (although in dark moments I worry that more are soon to follow). Desmostylians were large quadrupeds adapted to life in the water. They had short tails and mighty limbs. Because of this morphology, taxonomists initially thought that they were cousins of proboscideans and sirenians (elephants and manatees), but the fact that their remains have only been found far from Africa (the origin point of elephants, mammoths, mastodons, and manatees & sea cows) along with perplexingly alien traits has caused a rethink of that hypothesis.
(Art by Ray Troll fror SMU)
Extant between the late Oligocene and late Miocene, the desmostylians had powerful tusklike cylindrical teeth and dense heavy bones. The smallest (and oldest) were peccary sized creatures whereas the largest grew to the size of medium whales. It seems like desmostylians lived in littoral parts of the ocean—near coasts and shores where they used their pillar like teeth to graze great kelp forests. They scraped or rasped up the kelp and sucked it down their voracious vacuum maws like spaghetti! It must have been an astonishing sight! My favorite marine paleoartist, Ray Troll has made exquisite pictures of these majestic creatures which help us to visualize them. I really hope they looked this funny and friendly (if they were anything like herbivorous manatees, they probably did!).
(Art by Ray Troll, courtesy SMU)
Speaking of manatees, the gentle sirenians had a hand (or flipper?) in the demise of the poor desmostylians. The dugongs and manatees would never fight anyone or even protect themselves with force—they simply outcompeted the less nimble desmostylians for resources, although one wonders if climate-change and the continuing evolution of different coastal sea plants might also have helped do in the great desmostylians.
The Giant Armadillo (Priodontes maximus)
We boldly continue armor week with an overview of the magnificent armadillo family. This order of armored mammals (Cingulata) is more diverse than any other sort of armored mammals–outshining even the scaled pangolins. Today the only living members of the Cingulata order are the armadillo family (a successful group consisting of more than 20 living species) but the armadillos’ extinct cousins were once far more widespread and bizarre. These relatives included the pampatheres–long plantigrade browsing creatures covered in banded armor who roamed the continent from one end to the other. Even more impressive were the glyptodonts, massive tank-like creatures bigger than a compact car.
A fossil glyptodon, fossil pamphathere, and armadillo skeleton (in the far right corner)
The Cingulata order is part of the superorder Xenarthra. Separated from all other placental mammals for over 100 million years (due to South America’s unique isolation after the breakup of the southern supercontinent Gondwana), xenarthrans evolved in different directions from other mammals. The unique challenges and opportunities of their island continent resulted in bony domed giants like the pampatheres and glyptodonts, both of which are characterized by tortoise-like body armor composed of bone segments (osteoderms). The glyptodonts were unlike tortoises in that they could not draw their head beneath their shells: instead their heads were protected by bony caps atop their skulls. The largest glyptodonts could grow to 4 metres long, 1.5 metres high and have a mass of 3 tons (Ferrebeekeeper has already written about the smallest known Cingulata species—the pink fairy armadillo, which can still be found living in the central dry lands of Argentina).
Glyptodon
Thanks to convergent evolution the herbivorous glyptodonts resembled other armored giants like cryptodire turtles and ankylosaurs. One species of glyptodont, Doedicurus clavicaudatus, even had a heavy spiked tail (although it is unclear whether this was used against predators or to compete for territory and mates).
Doedicurus clavicaudatus
When the first members of the Cingulata order emerged in the Myocene, the top predators of South America were giant running predatory birds–the Phorusrhacidae, which resembled giant dashing eagles up to 3.2 metres (10 ft) high. The glyptodonts, pampatheres, and armadillos outlasted these terror birds and they then outlasted the carnivorous metatherian mammals (with terrible saber teeth) which followed. When the Isthmus of Panama connected South America with North America (and therefore with an entirely new universe of ultra-competitive mammals), the armored cingulatans competed just fine with the newcomers. Some glyptodonts and pamphatheres wandered up through Central America and found new homes in North America. The armadillos are still there. However at the end of the last ice-age, a new African species arrived and brought a devastating and final end to the glyptodonts, the pampatheres, and most of the armadillos. But even this newly arrived predator seemed impressed by the greatest of armored mammals. An Argentine anthropologist even reports discovering a site twenty leagues from Buenos Aires where early human hunters had used glyptodont shells as dwelling places.
Human Hunters Stalk a Glyptodon (Heinrich Harder)
ferrebeekeeper 