coelacanth are giant Pisces with large , fleshy fins , and they were conceive to have go extinct millions of eld ago until they were discover swimming in abstruse amnionic fluid off the coast of South Africa in the Indian Ocean in1938 . These so - call “ populate fossils ” breathe using gill , but fit in to a newNature Communicationsstudy , today ’s coelacanths also have a well - develop lung . While this lung is likely not functional , it suggest at how ancient lobe - finned fish lived 410 million years ago .
With fleshier Phoebe than , say , Salmon River or trout , coelacanth resemble the fish that made the changeover onto land around360 - 390 million years ago , which became the root of all tetrapods ( four - limbed vertebrates like us ) . Nowadays , you could find these rarefied , two - meter - long giant star living in jumpy habitats between 110 and 400 metre deep in the coastal waters of the Mozambique Channel and Sulawesi , Indonesia . Unlike fossil coelacanths , bread and butter coinage lack a lung that ’s calcified , or sheathe in bony plate – these were thought to be an version to shallow water . As coelacanths recede their lung over clip there was a parallel development of a unique adjustment to deep water surroundings : a fatty pipe organ use as a buoyancy control .
Researchers did n’t know if any remnants of the lung had been keep back in advanced coelacanth anatomy . So to investigate , a team leave by Paulo Brito from theUniversidade do Estado do Rio de Janeiroused x - shaft of light imaging to make 3D reconstructions of five developmental stages ( from fertilized egg to adult ) of a living coelacanth specie calledLatimeria chalumnae(pictured below ) .
The researchers found a potentially functional , well - developed lung in the early embryo microscope stage . However , lung development is dramatically slow up during subsequently embryonic , juvenile , and adult stage – eventually becoming functionless , or rudimentary . “ The lung now has no function at all , ” Brito told theLos Angeles Times , “ just like our appendix . ”
Furthermore , with dissections , 3D reconstructions , and tissue studies , the researchers also happen pocket-sized , flexible plates scattered around the vestigial lung in adults . These structures might be similar to the calcified lung of nonextant Latimeria chalumnae , helping them regulate lung intensity . They were finally lost as the fish became adapt to deep - water environments . This adaptation may have helped some Latimeria chalumnae make it when the ( non - avian ) dinosaur and shallow - urine Latimeria chalumnae did n’t . They were safer from the post - star-shaped environmental crisis .
Three - dimensional reconstructions of the pulmonary complex of L. chalumnae at different ontogenetic stages . lily-livered , esophagus and stomach ; green , roly-poly electronic organ ; red , lung . Brito et al . Nature Communications
