About 90 % of all an­i­mal species have still not been iden­ti­fied by hu­mans. Many of the creatures have con­quered small nat­u­ral niches or ex­ist in de­serted re­gions, where they are liv­ing un­der cover – un­til sci­en­tists dis­cover their hid­ing places.

Science Illustrated - - CONTENTS -

Think you know an­i­mals? Not even science knows all the an­i­mals. Hun­dreds - if not mil­lions - of species re­main to be dis­cov­ered.

From the deck of the ship, sci­en­tists lower a cus­tom­ized un­der­wa­ter el­e­va­tor into the wa­ter to­wards the deep­est place on Earth, the Mar­i­ana Trench in the Pa­cific Ocean. The el­e­va­tor can reach a depth of 11 km. On the way down, cam­eras will record life in the un­ex­plored "ter­rain". The sci­en­tists have also placed mack­erel on the el­e­va­tor to at­tract fish and other hun­gry ma­rine an­i­mals, so the el­e­va­tor can func­tion as a kind of fish trap, which can bring spec­i­mens to the sur­face.

The trip to the ocean floor lasts about four hours, dur­ing which the cam­era cap­tures fas­ci­nat­ing footage of large rock gre­nadiers and cusk-eels, and af­ter a cou­ple of hours, the el­e­va­tor fi­nally reaches the up­per Mar­i­ana Trench. Fish have never be­fore been ob­served at such ex­treme depths, and so, sci­en­tists open their eyes wide, when they see an odd lit­tle fish swim­ming about at a depth of 8 km. There is no doubt that they have just dis­cov­ered a new species.

Mil­lions of new species

The fish is one of 15,000-18,000 new species that are added to bi­ol­o­gists’ list of all the world’s an­i­mals an­nu­ally. Not sur­pris­ingly, dis­cov­er­ies of new in­sects make up a large por­tion of the finds, but once in a while, sci­en­tists also some across large, un­known an­i­mal species such as a new orang­utan dis­cov­ered in Su­ma­tra in 2017.

Ac­cord­ing to a study made by sci­en­tists from Canada and Hawaii, bi­ol­o­gists might have many more new ac­quain­tances to look for­ward to. Via sta­tis­ti­cal analy­ses, the sci­en­tists cal­cu­lated that some 86 % of all ter­res­trial species and 91 % of ma­rine species have not yet been iden­ti­fied. The cal­cu­la­tion showed that the world is the home of 8.7 mil­lion an­i­mal species, of which only about 955,000 have been clas­si­fied as we speak. The ma­jor­ity of the

un­known species are an­i­mals that might be dif­fi­cult to find for dif­fer­ent rea­sons. They could be very small or hide in imag­i­na­tive and im­pass­able places. So, sci­en­tists es­ti­mate that 7.7 mil­lion an­i­mals – or about 88 % of all species – re­main un­known.

Al­though at first sight, the num­ber seems very high, his­toric ex­am­ples in­di­cate that the cal­cu­la­tion is cor­rect. In 1980, a team of sci­en­tists ven­tured into Panama’s trop­i­cal for­est to ex­plore the im­mense bio­di­ver­sity. Their stud­ies of 19 trees caused the dis­cov­ery of 1,200 dif­fer­ent bee­tle species, of which 80 % were un­known.

Rare species

The many species can re­main undis­cov­ered, be­cause they of­ten live in ex­tremely small niches and only in one spe­cific place in the world, in one par­tic­u­lar for­est, or in one par­tic­u­lar lake.

When Bri­tish sci­en­tist Charles Darwin went to the Gala­pa­gos Is­lands aboard the HMS Bea­gle, he en­coun­tered lots of new, un­known an­i­mal species that had lived in iso­la­tion in the re­mote ter­ri­to­ries. And Earth in­cludes many sim­i­lar small is­lands, which are the homes of rare an­i­mals and unique ecosys­tems. The world’s small­est chameleon, Brooke­sia micra, has just been found on the small, rocky, des­o­late is­land of Nosy Hara off north­ern Mada­gas­car, where the 30- mm- long chameleon lives in cracks in the rocks.

Earth’s lush rain­forests such as in Bor­neo and Mada­gas­car are also known to be ripe with unique wildlife, and sci­en­tists al­most can­not help be­ing suc­cess­ful, when they go on ex­pe­di­tions to dis­cover new species. It is more dif­fi­cult for sci­en­tists in the huge oceans, which cover 71 % of the world’s area. Only a frac­tion of the ocean floor has been mapped out, and many places are dif­fi­cult to ex­plore due to the depths and the high pres­sure far be­neath the sur-face. So, sci­en­tists an­nu­ally “only” dis­cover 1,500-2,000 new ma­rine an­i­mals, al­though the oceans prob­a­bly in­cludes mil­lions of more of them. How­ever, sci­en­tists need not al­ways go to ex­treme depths to find new species. In 2013, a new her­mit crab was caught by a trawler at a depth of 200-300 m off the west coast of South Africa. The species is spe­cial, be­cause it does not use aban­doned sea shells, etc., as its house like other cray­fish do, rather it car­ries a home made of liv­ing, anemone-like creatures on its back. Dis­cov­ery re­veals spe­cial gifts Ex­am­i­na­tions of the snail­fish from the Mar­i­ana Trench have shown that the fish uses an un­known adap­ta­tion strat­egy to sur­vive un­der the in­tense pres­sure at a depth of 8 km. Sci­en­tists have found spe­cial en­zymes in the fish’s mus­cles, which are adapted to func­tion op­ti­mally un­der the high pres­sure, and they have ob­served high lev­els of the TMAO com­pound in the cells, which pro­tects pro­teins from col­laps­ing. By copy­ing the fish’s bi­ol­ogy, sci­en­tists might be able to help divers ex­plore even larger ocean depths, where they could dis­cover more of the mil­lions of species, which con­tinue to live in hid­ing.

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