March- April, 19i5 



CHICAGO NATURAL HISTORY MUSEUM BULLETIN 



Page S 



A FISH STORY— TRUE, AND STRANGER THAN ANY FICTION 



By MARION GREY forebears obviously have done, or can con- 



Assoc,ATE.Dw.s.oN OF FISHES ^.^^^ cvolution to mcct Hew conditioHs. 



Other species, such as some of the flightless 

 birds that have become extinct in recent 

 times, can neither hold their own against an 

 invasion by stronger or more agile competi- 

 tors, nor can they retreat to a restricted and 

 perhaps safer ecological niche, as Latimeria 

 and the lungfishes have been able to do. 



The nearest known relative of Latimeria 

 lived in the Cretaceous period, more than 

 65,000,000 years ago and the group to which 

 it belongs, the Crossopterygia ("fringe- 

 finned ganoids") dates even farther back — 

 to the Devonian period in fact, about 

 350,000,000 years ago. This was before 

 the invasion of the land by the amphibians, 

 and it was forms not unlike the crossoptery- 



There has recently been placed on exhibi- 

 tion in the Hall of Fishes (Hall O) a model 

 of Latimeria chalumnae, a fish with a remark- 

 able history. 



In December, 1938, fishermen in a trawler 

 off the coast of South Africa found, in addi- 

 tion to their usual catch a strange bright 

 blue fi.sh, five feet long, thrashing about in 

 their nets. The trawl-net had been hauled 

 from forty fathoms (240 feet) about three 

 miles offshore, near East London and off 

 the mouth of the Chalumna River. 



The fish was entirely unlike any they had 

 ever seen before. Its body was covered with 

 heavy bony scales. Most of the fins were 

 fleshy and limb-like, and the creature was 



LIVING EXAMPLE OF A 350.MILLION YEAR OLD TYPE 

 Ljtimeria chalumnae, a relic of past ages, discovered in 1938. Unlike anything known in the modern fish world before, it 

 has a double tail corresponding to that of fossil relatives, and large fleshy fins which in the older species foreshadowed the 

 development of limbs for locomotion on land. 



equipped with what seemed like two tails, 

 one large and fleshy, the other a small 

 structure attached to the end of the larger 

 one. Because the ship's captain recognized 

 the creature as something unusual, the 

 mounted skin found its way to Dr. J. L. B. 

 Smith of Rhodes University at Grahams- 

 town, who described it for science as 

 Latimeria chalumnae. 



The discovery of Latimeria gives hope 

 to the scientific world that the ocean deeps 

 may shelter other relicts driven from their 

 former habitats by modern animals that are 

 better fitted to exist under modern living 

 conditions. Most types of animals cannot 

 persist through the ages as Latimeria has 

 done. The more perfectly a species evolves 

 to suit its environment, the less chance it 

 has of surviving a change — either sudden or 

 gradual — in that environment. 



A more generalized species can adapt 

 itself to a new habitat, as this animal's 



gian fishes that began the invasion by the 

 backboned animals. Amphibians, reptiles, 

 mammals, and finally man himself were in 

 turn developed out of those first elementary 

 land vertebrates. 



Latimeria has come down through the 

 ages so little changed that it can unquestion- 

 ably be placed in the system of classification 

 close to the extinct family Coelacanthidae. 

 Reconstructions of fossil coelacanths made 

 by paleontologists bear an amazing likeness 

 to the living specimens, and it is a remark- 

 able circumstance that a remnant of such an 

 old group should have undergone so little 

 evolutionary change through so many 

 millions of years. 



The discovery of living lungfishes in 1871 

 was an important scientific event, as these 

 creatures had also been thought until that 

 time to be extinct. They had long been 

 known from well preserved and abundant 

 fossils. The lungfishes are relatives of the 



LATIMERIA'S ANCIENT RELATIVE 



Prehistoric fish called Undina penicillata by paleontolo- 

 gists. It lived about 150,000,000 years ago, and typifies 

 others going back as far as 350,000,000 years. The simi' 

 larity of its fins and double tail to those of the modern 

 Latimeria is readily apparent. 



fringe-finned ganoids, and the discovery of 

 Latimeria forms a striking parallel to the 

 history of the knowledge of these fishes. 



Relicts (often called "living fossils") of 

 groups of animals formerly abundant and 

 now reduced to a small remnant are by no 

 means uncommon, although usually the 

 modern representatives are far more changed 

 by time than Latimeria has been. Land 

 forms have in many cases retreated to the 

 southern continents, and the marine relicts 

 mostly to the tropical or to the deep seas. 



MUCH SEA LIFE UNKNOWN 



Modern fishing methods are by no means 

 adequate to catch all of the large swift- 

 moving animals that might be found beneath 

 the surface, nor are they efficient enough to 

 secure a fully representative collection of the 

 sea's inhabitants. The fact that trawls and 

 other devices used to explore the ocean have 

 brought up very few large animals does not 

 mean, as has sometimes been supposed, that 

 there are no more to be found. 



William Beebe, who descended as far as 

 half a mile beneath the surface of the sea in 

 the bathysphere, disproved the supposition 

 that the unlighted depths are but scantily 

 populated. He found that the proportion 

 of living things seen was infinitely greater 

 than had been assumed when judging from 

 the results of daily catches. 



MODEL HERE UNIQUE 



The model of Latimeria chalumnae is the 

 work of Mr. Leon L. Pray. His thorough 

 knowledge of fish taxidermy combined with 

 the excellent detailed photographs and 

 descriptions by Mr. J. L. B. Smith have 

 enabled Mr. Pray to produce a model 

 unique among museum exhibits. 



The new model fits very naturally into a 

 panel exhibiting other "living fossils" among 

 fishes. Its nearest relatives, shown with it, 

 are the lungfishes, which have fleshy-lobed 

 fins, and which are likewise relicts from the 

 Paleozoic Age. 



The most astonishing of all such relict 

 forms, perhaps, are the lampreys, whose 

 relations to the earliest fossil fish-like 

 creatures have only recently been estab- 

 lished. More familiar to us in North 

 America are the gars and sturgeons, whose 

 living representatives are likewise relics of 

 the life of past geological ages. 



