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/A Diversity of Aquatic Life

Old Four Legs, Itself!

the Coelacanth, Latimeria chalumnae

 

By Bob Fenner

 

Do you really like fish? I mean really; are you a true a A Fish E Ah Nay Dough? Well, if aquatics are your passion, this, The Story of the Coelacanth (actually the title of a book by Keith S Thomson) is for you. Maybe just a smidgen from it: (p.133)

"Nature always has a few ringers of course- like ducks that next in trees, kangaroos that climb trees, or fishes that walk on land. In fact, fishes alone are so diverse that we can point to the climbing perch, the flying fish, and the walking catfish... We can reconstruct a lot of the behavior and even physiology of an organism from incomplete evidence, such as the skeleton or a fossil, without ever seeing the whole living organism or being absolutely sure we are right. Putting it more scientifically, we can make a number of hypotheses and hope to test them more fully as the direct evidence slowly comes in. Strictly speaking, you can never "prove" hypotheses; what scientists actually do is try to amass more and more data that will turn out either to corroborate or refute their hypotheses. This makes science a lot of fun"... Couldn't agree more

Hey, here's your big chance to get a copy of J.L.B. Smith's coelacanth wanted poster, maybe get pumped up and join S.P.O.O.F. (the society for the protection of old fishes, I'm not joking), and learn such great humor as; "Why did the Eusthenopteron cross the road? To become a Lissamphibian" Ha Ha, Ho Ho, no, stop, I'm slaying myself. Cause just what the heck is that thing? The/A Missing Linko? Well, no, and yes, a little. Well read on!

Classification: Taxonomy, Relation With Other Groups

Oh boy, where to begin? There is but one species of living coelacanth (known), and maybe fifty acknowledged extinct varieties. This is therefore a monotypic genus, family, order... but we're getting ahead of ourselves here! Let us start again and try to put this critter in it's place and time:

For review, our favorite group of vertebrates (fishes) occupy three of the seven living classes of vertebrates, the other four (tetrapods= four feet) being the amphibians (frogs, toads, salamanders, newts, caecilians), reptiles (lizards, snakes, crocodilians, turtles, the tuatara), birds and mammals. According to most popular/generally accepted arrangements there are/were two other extinct classes of vertebrates (fishes, yeah!). The minute placoderms and ostracoderms; but I digress. Ahem:

Perhaps something along the lines of the filter-feeding, jawless ostracoderms "gave rise" to the also jawless fishes (Class Agnatha) represented by their "degenerated descendants", the living hagfishes and lampreys. As the story goes, some stem line of the agnatha led to the Class Placodermata, which went extinct, but also led to the cartilaginous fishes (Class Chondrichthyes), the sharks, rays, skates and the weird chimaeras. Oh, and some of the placoderms went on to become the rest of the bony fishes (Class Osteichthyes). Now, pay close attention here. We're going to skip/gloss over the various sub-divisions of the advanced and not-so advanced bony fish types (teleosts, etc.) to focus and chat about the group at hand and it's affinities. Along the way to changing into extant forms the placoderms also gave rise to the lobe-finned fishes, the Sub-Class Crossopterygii (boy, that's a hard one to say), which in turn is the stem group that gave rise to the (tah-dah!) order including the family Coelacanthidae and the Order Rhipidistia. These rhipidistian fishes are all gone, but they resulted (sorta teleological eh?) in the living lungfishes, amphibians, and the rest of the tetrapods. Whew! Before you start to sing the words to "Say You Will", "You make me want to throw my hands up and shout", let me (and Dick Boyd, artist of FAMA) present a pictograph of these relationships:

Class Ostracodermata: Muck suckers from before the Devonian, giving rise to the

Class Agnatha led to/include the living jawless fishes and the

Class Placodermata which are extinct, but led to the

Class Chondrichthyes and the

Class Osteichthyes including the un & advanced so bony fishes &

Subclasses Coelacanthini (just our one species) and Rhipidistia which all died out, except luckily>

Order Dipnoi, the lungfishes and very happily the Other four living Classes of Vertebrata, including us!

The scientific name is in honor of Marjorie Courtenay-Latimer who brought the original sample specimen to the soon to become ichthyologist J.L.B. Smith's attention; and the river of South Africa, the Chalumna, where that individual was trawled up from in the sea of 1938.

So the fossil coelacanths are pretty well known from 350 to 70 million years ago, and then zip! What Gives? What happened? What; did they go the way of the big dinosaurs? I have my own theory of a large oil seepage that lit on fire and left the iridium ring-around-the-planet, smoked all the large aerial respirators, and, allright, back to the story at hand.

Natural and Introduced Range

Most subsequent coelacanths have been captured with "native" long-line techniques off the Comoro Islands. A few have been collected via fish markets in Indonesia in the later years of the 1990's.  A bi-zillion (eighty million plus) years ago, the group was widespread in tropical to temperate freshwaters.

Selection: General to Specific

Good luck. None available as yet at any price. There have been a number of excursions intended to secure a big-bucks-draw specimen or two for profit/public aquaria. No success yet.

Environmental: Conditions

Habitat

You'll probably need a pressurized, chilled, low-lit system of several thousands of gallons capacity. Latimeria gets to be at least five feet long and couple of hundred pounds. They live and possibly vertically migrate nocturnally up to a depth of a few hundred feet from deeper. The original specimen collected was at seventy (70) fathoms, at six feet a fathom. Others have hailed from one to two hundred meters.

Okay let's see, they naturally live off steep volcanic islands, so keep that in mind when arranging the decor. Footage obtained through the study/dives of Hans Fricke, adventurer, cinematographer, and friendly neighborhood pet-fish ichthyologist, via his submersible, Geo show the coelacanth prefers plenty of cavities, or maybe the prey occupying those nooks and crannies.

Chemical/Physical

A good quality of synthetic sea salt, prepared at a "normal" higher specific gravity @ 1.025 should do, as well as natural sea water, of course. Latimeria is probably not too sensitive to ammonia or other metabolite poisoning; one odd biological fact re it's physiology is that it "has the blood of a shark" (G.E. Pickford) the storage of non-protein nitrogen (a combo of ammonia and carbon dioxide, the familiar urea) in it's blood at isotonic (same concentration) as seawater, helping the species keep out salts. They also have a rectal gland like sharks, hmmmmm.

Biology/Other

Man, this is a big category. As you'll note below, living coelacanths display a "stiff" nose to tail body orientation, not throwing their bodies into sigmoid curves or wagging their tails as so many advanced fishes are wont to do. Kinda reminds you of...yep, electrogenic fishes like mormyrids and various groups of knifefishes, eh? Well, guess what. That's-a right, coelacanths are suspected of having a weak electromagnetic sense. They have a peculiar rostral organ... pit organs sort of like sharks Ampullae of Lorenzini... for prey detection, navigation, communication???

& their skulls! Similar to amphibians, the skull possesses a joint allowing the head to move in such a way to enable objects to be sucked into the mouth, to expand and rotate their bite.

Their blood hemoglobin functions best at temperatures between 57 and 60 degrees Fahrenheit, so get the big chiller.

Filtration

Rapid sand or at least power-head driven undergravel. Is wet-dry asking for too much? Definitely use a protein skimmer.

Display

Get the net! I mean a really big one. See above, geez.

Behavior: Territoriality

Maybe Hans Fricke will be enlightening us soon, eh?

Introduction/Acclimation

Float for a good fifteen to twenty minutes without opening the bag... wait a minute! Actually, some novel, pressurized sealed tubes and other gear and procedures have been proposed for surfacing and reducing transplant shock. But don't mix the shipping water; ahem, thank you.

The fat-filled swimming bladder is a plus in preventing embolism on rapid ascent after capture, should your specimen survive respiratory distress.

Predator/Prey Relations

Probably just large sharks and you and I as predators.

Reproduction, Sexual Differentiation:

Seperate sexes. Females have been caught with as many as nineteen eggs, each of them the size and color of an orange. Males have erectile anal fin flaps which probably facilitate internal fertilization. Looks like there is some nourishment of embryos in their mother's oviducts, so looks like we have an ovoviviparous species here. Gestation time estimated to be about thirteen months.

Sound like a real money-maker for the serious fish culturist? Well don't go counting those Breeder Award Points quite so quickly; our friend reaches maturity very late, apparently at about twenty years. That's what you get for having such a slow metabolism.

Locomotion:

Surprisingly, live specimen following and photo-work has shown the coelacanth to be a sort of floater and rower, not moving it's pointed caudal much at all, but instead stroking it's fleshy second dorsal and anal and to a lesser degree, pectoral and pelvic fins, and kind of gliding along slowly.

Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes

Will probably take Tetra Marin and most meaty prepared foods. Of the hundred and fifty or so legitimate specimens taken, tummie contents reveals a totally piscivorous diet.

Disease: Infectious, Parasitic, Nutritional, Genetic, Social

Susceptible to ich. Suggest prophylactic freshwater dips. Okay, only joking. No parasitic or infectious disease noted.

Questions/Close:

The actual details of Miss M. Courtenay-Latimer's involvement, notification of Dr. J.L.B. Smith, his adventures with Latimeria are best retold with a reading of Thomson's account.

If you're super-interested in Latimerias biology and safe-keeping there is a group similar to the genus Cyprinodon's champion, the Desert Fish Council, for the coelacanth. The Coelacanth Conservation Council attempts to keep the public abreast of developments in conserving the species in view of it's apparent habitat/range limitation, low reproductive potential, and tremendous potential for destruction in the face of fishing pressure. Relief from poverty by local fishing effort is important in this very poor country. Rewards range up to three year's salary.

The fish is currently protected by CITES Appendix I classification, but due to entertainment demand I believe in our lifetime we will see more of this species, probably alive in a public aquarium.

Bibliography/Further Reading:

http://www.dinofish.com/

Balon, Eugene K. 1990. The Living Coelacanth Endangered: A Personalized Tale. T.F.H. 2/90.

Maisey, John G. 1987. New Fossil Coelacanth Named After Dr. Herbert R. Axelrod. T.F.H. 11/87.

Fenner, Robert (who?). 1988. Electric Fish. Aquarium Fish Magazine, 12/88.

Frickhinger, K.A. Fish Fossils Continued- but this time, living fossils! (ADI) Aquarium Digest Intl. #36, undated.

Meluso, Arsey. 1959. Scientific Curiosities: Living Fossils. TFH 5/59.

Thomson, Keith S. 1991. The Story of the Coelacanth. W.W. Norton & Co., N.Y.


BBC E-mail: Genome of living fossil; sequenced      3/18/13
> Peter Catterick saw this story on the BBC News website and thought you should see it.
> ** Genome of 'living fossil' sequenced **
> The genome of the coelacanth fish - a "living fossil" - is sequenced by scientists.
> < http://www.bbc.co.uk/go/em/fr/-/news/science-environment-22184556
> ** BBC Daily E-mail **
> Choose the news and sport headlines you want - when you want them, all
> in one daily e-mail
> < http://www.bbc.co.uk/email >
 Very interesting. Thanks. B

Another olde fish: A fabulous Xiphactinus mount at Ripley's Toronto, Canada Aquarium. A fish that "went" extinct about 65 million years ago... Up to... SIX meters long. This one had part of a Mosasaur flipper in its preserved stomach!

 

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