Posts tagged fish
Top left: Hippocampus sp. internal structure
Top right: Short-snouted seahorse - Hippocampus hippocampus
Center: 1. Syngnathus hippocampus [now Hippocampus hippocampus]
2. Pegasus draconis [now Eurypegasus draconis] - the Little Dragonfish (*unrelated to Syngnathidae family*)
3. Syngnathus pelagicus - the Sargassum pipefish
Bottom: Phyllopteryx taeniolatus -the Weedy Sea Dragon
Despite their remarkable appearance, seahorses are true ray-finned bony fishes (class Actinopterygii, infraclass Teleostei), along with bass, mullets, eels, salmon, and lanternfish.
Many people know of the male seahorse incubating the eggs and giving “birth” to 100-1000 offspring after they hatch, but reproduction is similar throughout the order Syngnathidae (including the seahorses, leafy and weedy sea dragons, and pipefish). There’s a persistent myth that seahorses are monogamous, but that’s not strictly true. The majority of species are serially monogamous, and remain together throughout the mating season (until the male births the babies).
Another remarkable thing about seahorses (Hippocampus spp.) is that they’re the only fish with prehensile tails - even their close relatives, the sea dragons and pipefish, don’t have this adaptation. However, since the seahorses are the only ones that swim upright, and they have the poorest locomotive skills, they need to be able to anchor themselves to the sea flora in order to not be swept away. The Guinness Book of World Records has named Hippocampus zosterae, the dwarf seahorse, the slowest fish in the world, moving less than 5 ft [150 cm] an hour.
Aside from the seahorses, the razorfish (Aeoliscus strigatus) is the only other fish to swim “upright”.
Images:
Bulletin of the United States Fish Commission, Vol 1. 1881.
Arcana; or, The Museum of Natural History. George Perry, 1811.
Top: Bichir and trunkfish [top], Electric Catfish [bottom]
Center: Electric “eel” - Electrophorus electricus
Bottom: Indo-Pacific Moray Eel - Muraena nudivomer (now Gymnothorax nudivomer)
A while ago I saw this Bird and Moon illustration of animals with misleading names, but I kept seeing people asking, “Ok, if they’re not THAT, then what ARE they?” For some reason, I completely forgot that I wanted to cover those questions, but hey, better late than never!
The electric eel isn’t an eel - it’s a knifefish. Knifefish (Gymnotiformes) are actually more closely related to electric catfish (Siluriformes) than they are to true eels (order Anguilliformes), but developed their electroconductive organs through convergent evolution - the first signs of the organ evolution in both the electric eel and the electric catfish appeared after they shared a common ancestor.
In addition to electric eels and electric catfish, electric rays (order Torpediniformes) are the only other “strongly electric” fishes - that is, fish that produce electric shocks over one volt, and use their electrogenerative organs to either stun or kill prey and/or attackers. There are many fish that can produce a small current (“weakly electric”), but it is used for electrolocation and electrocommunication, instead.
Images:
Fishes of Zanzibar: Acanthopterygii. J. Van Voorst, 1866.
The Standard Natural History. John Sterling Kingsley, 1884.
Wild life of the world. Richard Lydekker, 1915.
Modern fishing vessels catch staggering amounts of unwanted fish and other marine life. It’s estimated that anywhere from 8 to 25 percent of the total global catch is discarded, cast overboard either dead or dying. That’s up to 27 million tonnes of fish thrown out each year — the equivalent of 600 fully-laden Titanics. And the victims aren’t just fish. Every year, an estimated 300,000 whales, dolphins and porpoises die entangled in fishing nets, along with thousands of critically-endangered sea turtles.
All modern forms of commercial fishing produce bycatch, but shrimp trawling is by far the most destructive: it is responsible for a third of the world’s bycatch, while producing only 2% of all seafood.
Shrimp (and many deep-sea fish) are caught using a fishing method called bottom trawling, which usually involves dragging a net between two trawl doors weighing several tons each across the ocean bed. This has a destructive impact on seabed communities, particularly on fragile deep water coral – a vital part of the marine ecosystem that scientists are just beginning to understand. The effect of bottom trawling on the seafloor has been compared to forest clear-cutting, and the damage it causes can be seen from space. The UN Secretary General reported in 2006 that 95 percent of damage to seamount ecosystems worldwide is caused by deep sea bottom trawling.
Relevant to my post on “Chilean Sea Bass”.
Patagonian Toothfish - Dissostichus eleginoides
Have you ever eaten “Chilean sea bass”? Just like sardines, they’re not actually a “real” fish species - they’re what’s been known for over a century as the Patagonian toothfish; in the UK and most other places in the world, they’re still called “toothfish”.
A man named Lee Lantz created the term “Chilean sea bass” in 1977, and the FDA approved it as an “alternative market name” in 1994. Since then, fisheries have been harvesting this predatory Antarctic fish en masse, and selling it like hotcakes to the restaurant and supermarket industries. The mild-but-fishy taste that’s stronger than your standard “whitefish” is easy to mix with other flavors, and the fish themselves can reach up to 20 lbs - big fish which are easy to sell by bulk weight.
Unfortunately, the regulation of fisheries that harvest the Patagonian toothfish is rather lacking. Unlike other fishery operations (such as the Caribbean swordfish industry), the companies that fish the Antarctic waters have largely not changed their practices in decades, despite recent calls to protect the endangered fish and mammals that are known to be killed by the practices used to over-harvest these profitable fish. That’s on top of depleting the natural populations of the fish to a point where they’re unable to repopulate their native seas, leading to a serious imbalance in the ecosystem.
If you have a choice in fish, trust me, “Chilean sea bass” isn’t the best out there. And until the fisheries operating in the Antarctic change their practices, you’re almost certainly helping to save the lives of endangered animals, and preserving what we already know to be an incredibly fragile ecosystem. Just a thought, next time you buy fish.
Black Piranha - Serrasalmus rhombus
The black piranha (also known as the redeye or rhombeus piranha) has recently been discovered to have a bite force as strong as the estimated force of the extinct Megapiranha.
Though the negative stigma towards piranhas is largely undeserved, the mature black piranha is one of the most aggressive fish. This is especially true recently, with the over-fishing of the Amazon and Orinoco rivers, depleting the food sources of the adult fish.
Most species of juvenile piranhas feed on the scales and fins of others fish. Yes, they will swim up to, and rip the fins off of big fish, especially as they near maturity, but are not yet large enough to reliably hunt down other fish.
Despite their huge size (up to 1 m long, four times longer than adult black piranhas) and extremely strong bite force, the Megapiranha of the Pleistocene era (8-10 mya) wasn’t believed to have a solely carnivorous diet. Their saw-shaped teeth bear similarities to the Serrasalmus genus, but also to the teeth of the Pacu, or “vegetarian piranha”.
Expédition dans les parties centrales de l’Amérique du Sud, de Rio de Janeiro à Lima et de Lima au Para. Under direction of Le Comte Francis de Castelnau, 1856.
Look carefully at this fish. It may bring you good fortune!
No, no, coelacanths aren’t the fish of Yeh-Shen, but they were referred to as the “Wish Fish” in many telegrams between JLB Smith and his colleagues in Grahamstown and back in England - though there had been reports of a “foul-tasting, oily, hideous fish” going around for decades, it seemed that since the first specimen was recovered intact, all of the reports evaporated like magic. No one heard of any new “uglyfish” caught by locals, no one caught any in the tedious trawling missions sent out by Rhodes University, nothing.
The first report of a new intact Coelacanth that had been caught by a local who had seen a reward poster happened at a most inopportune time: two days before Christmas Eve! Oh, it may seem like the perfect Christmas gift to Smith, looking back, but at the time it was a disaster. The fish had been caught out on the Cape, the other side of the country! And to make things worse, the next day was a Sunday, followed by Christmas Eve, Christmas, and Boxing Day. There would be no way Smith could get to the fish in time to preserve it for science, because, as one visiting Portuguese friend once noted to him:
You may talk of Russia and the Iron Curtain, but it is nothing to South Africa on a Sunday or a holiday. That is an Iron Curtain. It shuts down, boom, boom, everything like that, and everything is dead!
A Sunday followed by three Bank Holidays was the worst possible outcome, especially since the trawler that the fish had come in on had to ship out again the day after Boxing Day.
Through an agonizing maze of run-arounds and unreachable telegraph lines, Smith and his team did eventually manage to stall the trawler one day, and alert the Prime Minister on Boxing Day that they (the Grahamstown team) had secured a coelacanth. Though by many he was considered an antagonist to the sciences, and doubly so to an extremely English center such as existed in Grahamstown, he saw the magnitude of this news, and saw what a boon it would be to South Africa to be able to announce it as soon as possible. With direct orders from the Prime Minister, the Minister of Defense procured a light airplane that could take Smith where he needed to go to retrieve the fish, and Smith’s team made preparations to announce everything on 27 December.
The Search Beneath the Sea: The Story of the Coelacanth. J. L. B. Smith, 1956.
The first well-preserved coelacanth, shortly after catch
Though the coelacanth was confirmed as not extinct by Marjorie Courtenay-Latimer in 1938, the first specimen suitable for complete study and display was not caught until 1952.
There were even more troubles getting to and preserving this fish than Latimer had with hers, but this time around, the resources and transportation to get to it in time were available. Well, sort of. The Prime Minister of South Africa himself had to get involved in order to have this newly-extant species preserved!The Search Beneath the Sea: The Story of the Coelacanth. J.L.B. Smith, 1952.
Latimeria chalumnae - Coelacanth
The coelacanth was assumed extinct until 1938, since fossils of it had been found long before, yet hadn’t ever been caught by anyone who recognized it (it was known as the “gombessa” by the Comoro Islands fishermen, and was considered a worthless fish to be disgarded, as it tasted awful). It’s thought to have evolved over 400 million years ago, and were originally assumed to have gone extinct in the Late Cretaceous period.
The Search Beneath the Sea: The Story of the Coelacanth. J.L.B. Smith, 1956.
Diaphanous Hatchetfish - Sternoptyx diaphana
There are approximately 40 species of marine hatchetfish, all with similar shapes, but varying in size from less than a silver dollar to almost six inches long. The upward-facing (but non-telescopic) eyes and downward-slanting mouth are characteristic of the Sternoptychinae family.
Like many deep-sea creatures, the hatchetfish have bioluminescent photophores on their body - unlike most other deep-sea creatures, though, the hatchetfish directly utilizes their bioluminescence in how they disguise themselves.
The low levels of light that they give off on the bottom half of their body reflect against their silvery scales, giving predators below them the impression that the only thing above is the sky (even if the sky might be thousands of meters above). Complimentary to that camouflage, the upper half of the hatchetfish is more darkly colored, giving predators above the impression that there’s nothing but open ocean below them. This type of camouflage is called “counterillumination”.
Résultats des campagnes scientifiques accomplies sur son yacht par Albert Ier, prince souverain de Monaco. Albert I, Prince of Monaco, 1911.
n562_w1150 by BioDivLibrary on Flickr.
![biomedicalephemera:
Marjorie Courtenay-Latimer
Curator of the Natural History museum in East London, South Africa, Marjorie Courtenay-Latimer was the first person to discover (in a meaningful way) that the coelacanth wasn’t extinct, but was simply the vile-tasting “gombessa” that had been thrown away for decades.
While collecting specimens and samples for the East London museum, Ms. Latimer let it be known to the local fishermen that she was highly interested in any “unusual” or rare fish that they might haul aboard. In 1938, Capt. Henrik Goosen phoned her to come down to the dock, where she encountered a five-foot long oddity, which she describes:
“I picked away at the layers of slime to reveal the most beautiful fish I had ever seen. It was five foot[feet] long, a pale mauvy blue with faint flecks of whitish spots; it had an iridescent silver-blue-green sheen all over. It was covered in hard scales, and it had four limb-like fins and a strange puppy dog tail.”
She hauled it back to the museum in a taxi (which she notes the cabbie was none too happy about, even when she gave a generous tip - I can’t imagine any taxi driver wanting fish slime on their seats!), and discovered that she could not find the fish in any of the books available to her. She was eager to preserve the specimen, and since the museum had no preservation facilities, she (in another taxi) took it down to the morgue, which wouldn’t have it. She then attempted to contact James [JLB] Smith at Rhodes, but he was out on holiday.
In the end, knowing that it could possibly end up being of dubious scientific value, she reluctantly ended up having the fish skinned and taxidermied. Luckily, the external anatomy of the coelacanth is so different from anything else in the sea, JLB Smith was able to positively identify the specimen:
“There was not a shadow of a doubt,” he said. “It could have been one of those creatures of 200 million years ago come alive again.”
Still, the taxidermy work had removed both the gill plates and the ossicles, which were needed for absolute confirmation that this was the fish of fossils. Now known as Latimeria chalumnae after his friend and the river it was discovered in, the discovery was announced to much excitement in the scientific community and local population. The fact that there was no complete positive proof that this fish was the fish of fossils still made many icthyologists doubtful about the specimen, but JLB Smith was absolutely determined to find proof of its identity.
And thus began the search for the Lazarus fish…
The Search Beneath the Sea: The Story of the Coelacanth. J. L. B. Smith, 1956.](http://25.media.tumblr.com/tumblr_luxeol7P0e1qk931ho1_400.jpg)
Marjorie Courtenay-Latimer
Curator of the Natural History museum in East London, South Africa, Marjorie Courtenay-Latimer was the first person to discover (in a meaningful way) that the coelacanth wasn’t extinct, but was simply the vile-tasting “gombessa” that had been thrown away for decades.
While collecting specimens and samples for the East London museum, Ms. Latimer let it be known to the local fishermen that she was highly interested in any “unusual” or rare fish that they might haul aboard. In 1938, Capt. Henrik Goosen phoned her to come down to the dock, where she encountered a five-foot long oddity, which she describes:
“I picked away at the layers of slime to reveal the most beautiful fish I had ever seen. It was five foot[feet] long, a pale mauvy blue with faint flecks of whitish spots; it had an iridescent silver-blue-green sheen all over. It was covered in hard scales, and it had four limb-like fins and a strange puppy dog tail.”
She hauled it back to the museum in a taxi (which she notes the cabbie was none too happy about, even when she gave a generous tip - I can’t imagine any taxi driver wanting fish slime on their seats!), and discovered that she could not find the fish in any of the books available to her. She was eager to preserve the specimen, and since the museum had no preservation facilities, she (in another taxi) took it down to the morgue, which wouldn’t have it. She then attempted to contact James [JLB] Smith at Rhodes, but he was out on holiday.
In the end, knowing that it could possibly end up being of dubious scientific value, she reluctantly ended up having the fish skinned and taxidermied. Luckily, the external anatomy of the coelacanth is so different from anything else in the sea, JLB Smith was able to positively identify the specimen:
“There was not a shadow of a doubt,” he said. “It could have been one of those creatures of 200 million years ago come alive again.”
Still, the taxidermy work had removed both the gill plates and the ossicles, which were needed for absolute confirmation that this was the fish of fossils. Now known as Latimeria chalumnae after his friend and the river it was discovered in, the discovery was announced to much excitement in the scientific community and local population. The fact that there was no complete positive proof that this fish was the fish of fossils still made many icthyologists doubtful about the specimen, but JLB Smith was absolutely determined to find proof of its identity.
And thus began the search for the Lazarus fish…
The Search Beneath the Sea: The Story of the Coelacanth. J. L. B. Smith, 1956.
Ocean sunfish - Mola mola
The Mola mola is the largest bony fish living today, and only the three largest sharks (the blue shark, basking shark, and great white shark) regularly outweigh this behemoth of the open ocean.
Like many of the giants of the animal kingdom, the sunfish has a diet that’s almost paradoxically nutrient-poor. All of the calories taken in by adult sunfish are provided by jellyfish and small fry and eggs of other fish, so they spend a large amount of their time eating. Their presence in an area can indicate nutrient-rich waters where endangered species can often be found.
The status of sunfish in the wild is not currently known, though they’re caught often enough that they’re assumed to not be threatened at this point. A multi-year survey of the worldwide sunfish populations is currently underway.
Image: Giant ocean sunfish caught by W.N. McMillan of E. Africa, at Santa Catalina Isl., Cal. April 1st, 1910. Its weight was estimated at 3,500 pounds.
Thornback ray (Raja clavata) and thornback ray skeleton
Like sharks, rays and skates have fully cartilaginous skeletons, which provide a stable structure but more flexibility than bone. You can see that, much like fish, rays have defined, er, rays, in their fins. The difference is that while fish tend to have a few unconnected rays and a taught taut tissue between them, the Rajiforms (skates and rays) have many, many rays, which are all connected perpendicularly by collagen. The body is then formed around these rays, which propel the Rajiforms forward in an undulating (wave-like) motion.
A history of the fishes of the British Islands. Jonathan Couch, 1863.
![Chironectes bifurcatus [now Rhycherus filamentosus] - The Two-pronged Toad-fish [now the Tasseled Anglerfish]
Despite its accepted current name as the “tasseled anglerfish”, this species is a true frogfish, from the family Antennariidae. While frogfish are members of the same order as all anglerfish (Lophiiformes), they are fairly specialized dwellers on the continental shelf, relying on camouflage to capture their prey, while the deep-sea (benthic) anglerfish rely much more upon stealth and the allure of their, er, lure.
In figure 1a, you can see the structure of the teeth of the tasseled anglerfish. While it doesn’t have the big, stabbing, pointy teeth of some of its cousins, the small, sharp, closely-linked teeth function like tiny hooks in its prey, preventing them from escaping while they’re being eaten. This gives us the additional fun fact that most frogfish (including this one) end up eating their prey while it’s still fully alive and conscious (or at least as conscious as a fish can be) - without any gnashing or tearing of the body, the only thing that kills the prey is suffocation and acid within the stomach.
Natural History of Victoria: Prodromus of the Zoology of Victoria. Decade VI. Frederick McCoy, 1881.](http://25.media.tumblr.com/tumblr_mca1ghMSHc1qk931ho1_400.jpg)
Chironectes bifurcatus [now Rhycherus filamentosus] - The Two-pronged Toad-fish [now the Tasseled Anglerfish]
Despite its accepted current name as the “tasseled anglerfish”, this species is a true frogfish, from the family Antennariidae. While frogfish are members of the same order as all anglerfish (Lophiiformes), they are fairly specialized dwellers on the continental shelf, relying on camouflage to capture their prey, while the deep-sea (benthic) anglerfish rely much more upon stealth and the allure of their, er, lure.
In figure 1a, you can see the structure of the teeth of the tasseled anglerfish. While it doesn’t have the big, stabbing, pointy teeth of some of its cousins, the small, sharp, closely-linked teeth function like tiny hooks in its prey, preventing them from escaping while they’re being eaten. This gives us the additional fun fact that most frogfish (including this one) end up eating their prey while it’s still fully alive and conscious (or at least as conscious as a fish can be) - without any gnashing or tearing of the body, the only thing that kills the prey is suffocation and acid within the stomach.
Natural History of Victoria: Prodromus of the Zoology of Victoria. Decade VI. Frederick McCoy, 1881.
![Pleuronectes rhumbus [now Scophthalmus rhombus] - The Brill
Like most flatfish, the brill has both eyes on the same side of its head, and it lives on the sea floor, with those eyes being the only exposed part of its body, allowing for effective ambush hunting, and hiding from predators.
Did you know that flatfish (the brill, flounder, sole, and their relatives) are actually born looking pretty normal? They have gas bladders for buoyancy, eyes on either side of the head, and are very non-flat. It’s only as they mature that they become the odd-eyed, floor-dwelling, pancakes of fish that we know.
Which makes me wonder…what the hell was “Flounder” in The Little Mermaid? Even as larval specimens, flatfish aren’t nearly that, er, rotund…
La Pèche et les Poissons; nouveau dictionnaire général des pêches. Henri de la Blanchère, 1868.](http://25.media.tumblr.com/tumblr_mbnsuumJVA1qk931ho1_400.jpg)
Pleuronectes rhumbus [now Scophthalmus rhombus] - The Brill
Like most flatfish, the brill has both eyes on the same side of its head, and it lives on the sea floor, with those eyes being the only exposed part of its body, allowing for effective ambush hunting, and hiding from predators.
Did you know that flatfish (the brill, flounder, sole, and their relatives) are actually born looking pretty normal? They have gas bladders for buoyancy, eyes on either side of the head, and are very non-flat. It’s only as they mature that they become the odd-eyed, floor-dwelling, pancakes of fish that we know.
Which makes me wonder…what the hell was “Flounder” in The Little Mermaid? Even as larval specimens, flatfish aren’t nearly that, er, rotund…
La Pèche et les Poissons; nouveau dictionnaire général des pêches. Henri de la Blanchère, 1868.
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A blog for all biological and medical ephemera, from the age of Abraham through the era of medical quackery and cure-all nostrums. Featuring illustrations, history, and totally useless trivia from the diverse realms of nature and medicine.
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