| lutrinae | Yes | | | mammals | subfamily | 169417 | click here |
| lutzomyia | Yes | | | invertebrates | genus | 7199 | click here |
| lycalopex culpaeus | Yes | species | eukaryota | mammals | species | 68736 | click here |
| lycalopex griseus | Yes | species | | | species | 68737 | click here |
| lycalopex gymnocercus | Yes | species | eukaryota | mammals | species | 425201 | click here |
| lycalopex vetulus | Yes | species | eukaryota | mammals | species | 68734 | click here |
| lycaon pictus | Yes | species | eukaryota | mammals | species | 9622 | click here |
| lynx | Yes | | | mammals | genus | 13124 | click here |
| lynx canadensis | Yes | species | eukaryota | mammals | species | 61383 | click here |
| lynx lynx | Yes | species | eukaryota | mammals | species | 13125 | click here |
| lynx pardinus | Yes | species | eukaryota | mammals | species | 191816 | click here |
| lynx rufus | Yes | species | eukaryota | mammals | species | 61384 | click here |
| maackia herderiana | Yes | species | eukaryota | invertebrates | species | 577130 | click here |
| macaca fascicularis | Yes | species | eukaryota | primates | species | 9541 | click here |
| macaca fuscata | Yes | species | eukaryota | primates | species | 9542 | click here |
| macaca mulatta | Yes | species | eukaryota | primates | species | 9544 | click here |
| macaca nemestrina | Yes | species | eukaryota | primates | species | 9545 | click here |
| macaca radiata | Yes | species | eukaryota | primates | species | 9548 | click here |
| macaca sinica | Yes | species | eukaryota | primates | species | 9552 | click here |
| macropus robustus erubescens | Yes | subspecies | | | subspecies | 1496120 | click here |
| macrosiphum euphorbiae | Yes | species | eukaryota | invertebrates | species | 13131 | click here |
| macrotus californicus | Yes | species | eukaryota | mammals | species | 9419 | click here |
| malacomys | Yes | | | rodents | genus | 112225 | click here |
| malus domestica | Yes | subspecies | eukaryota | plants | species | 3750 | click here |
| mammalia | Yes | | | mammals | class | 40674 | click here |
| mandrillus sphinx | Yes | species | eukaryota | primates | species | 9561 | click here |
| manidae | Yes | | | mammals | family | 9972 | click here |
| manis javanica | Yes | species | eukaryota | mammals | species | 9974 | click here |
| mansonia uniformis | Yes | species | eukaryota | invertebrates | species | 308735 | click here |
| mareca | Yes | | | | genus | 1526411 | click here |
| mareca penelope | Yes | species | eukaryota | vertebrates | species | 8838 | click here |
| mareca strepera | Yes | species | eukaryota | vertebrates | species | 75861 | click here |
| marmosets | Yes | no rank | eukaryota | primates | species | 38020 | click here |
| marmota caudata | Yes | species | eukaryota | rodents | species | 71802 | click here |
| marmota monax | Yes | species | eukaryota | rodents | species | 9995 | click here |
| martes | Yes | | | mammals | genus | 9658 | click here |
| martes flavigula | Yes | species | eukaryota | mammals | species | 74864 | click here |
| martes foina | Yes | species | eukaryota | mammals | species | 9659 | click here |
| martes martes | Yes | species | eukaryota | mammals | species | 29065 | click here |
| martes pennanti | Yes | species | eukaryota | mammals | species | 76720 | click here |
| martes zibellina | Yes | species | eukaryota | mammals | species | 36722 | click here |
| mastomys coucha | Yes | species | eukaryota | rodents | species | 35658 | click here |
| mastomys natalensis | Yes | species | eukaryota | rodents | species | 10112 | click here |
| mastomys sp. | Yes | no rank | eukaryota | rodents | species | 70830 | click here |
| maxomys surifer | Yes | species | eukaryota | rodents | species | 69081 | click here |
| mazama gouazoupira | Yes | species | eukaryota | mammals | species | 52407 | click here |
| medicago sativa | Yes | species | eukaryota | plants | species | 3879 | click here |
| megaderma lyra | Yes | species | eukaryota | mammals | species | 9413 | click here |
| megaderma spasma | Yes | species | eukaryota | mammals | species | 9414 | click here |
| megaptera novaeangliae | Yes | species | eukaryota | mammals | species | 9773 | click here |
| megoura viciae | Yes | species | eukaryota | invertebrates | species | 112273 | click here |
| melanogrammus aeglefinus | Yes | species | eukaryota | vertebrates | species | 8056 | click here |
| meleagris gallopavo | Yes | species | eukaryota | vertebrates | species | 9103 | click here |
| meleagris gallopavo intermedia | Yes | subspecies | eukaryota | vertebrates | subspecies | 109972 | click here |
| meles leucurus | Yes | species | | | species | 702266 | click here |
| meles meles | Yes | species | eukaryota | mammals | species | 9662 | click here |
| mellivora capensis | Yes | species | eukaryota | mammals | species | 9664 | click here |
| melogale | Yes | | | mammals | genus | 204266 | click here |
| melogale moschata | Yes | species | eukaryota | mammals | species | 204267 | click here |
| melogale moschata subaurantiaca | Yes | subspecies | | | subspecies | 1642406 | click here |
| melopsittacus undulatus | Yes | species | eukaryota | vertebrates | species | 13146 | click here |
| melursus ursinus | Yes | species | eukaryota | mammals | species | 9636 | click here |
| mephitidae | Yes | | | mammals | family | 119825 | click here |
| mephitis macroura | Yes | species | eukaryota | mammals | species | 30547 | click here |
| mephitis mephitis | Yes | species | eukaryota | mammals | species | 30548 | click here |
| mergus merganser | Yes | species | eukaryota | vertebrates | species | 8880 | click here |
| meriones unguiculatus | Yes | species | eukaryota | rodents | species | 10047 | click here |
| merlangius merlangus | Yes | species | eukaryota | vertebrates | species | 8058 | click here |
| merluccius productus | Yes | species | eukaryota | vertebrates | species | 89952 | click here |
| mesocricetus auratus | Yes | species | eukaryota | rodents | species | 10036 | click here |
| mesoplodon densirostris | Yes | species | eukaryota | mammals | species | 48708 | click here |
| metachirus nudicaudatus | Yes | species | eukaryota | mammals | species | 42725 | click here |
| microchiroptera | Yes | | | mammals | suborder | 30560 | click here |
| microgale cowani | Yes | species | eukaryota | mammals | species | 329863 | click here |
| microgale dobsoni | Yes | species | | | species | 1206715 | click here |
| microgale gymnorhyncha | Yes | species | | | species | 1497433 | click here |
| microgale jobihely | Yes | species | eukaryota | mammals | species | 364245 | click here |
| microgale longicaudata | Yes | species | eukaryota | mammals | species | 229052 | click here |
| microgale majori | Yes | species | eukaryota | mammals | species | 469768 | click here |
| microgale principula | Yes | species | eukaryota | mammals | species | 229053 | click here |
| microgale taiva | Yes | species | eukaryota | mammals | species | 364246 | click here |
| micromesistius poutassou | Yes | species | eukaryota | vertebrates | species | 81636 | click here |
| micronycteris megalotis | Yes | species | eukaryota | mammals | species | 148066 | click here |
| micropteropus pusillus | Yes | species | eukaryota | mammals | species | 77235 | click here |
| micropterus dolomieu | Yes | species | eukaryota | vertebrates | species | 147949 | click here |
| micropterus salmoides | Yes | species | eukaryota | vertebrates | species | 27706 | click here |
| microtus agrestis | Yes | species | eukaryota | rodents | species | 29092 | click here |
| microtus arvalis | Yes | species | eukaryota | rodents | species | 47230 | click here |
| microtus montanus | Yes | species | eukaryota | rodents | species | 88450 | click here |
| microtus oeconomus | Yes | species | eukaryota | rodents | species | 64717 | click here |
| microtus pennsylvanicus | Yes | species | eukaryota | rodents | species | 10058 | click here |
| microtus richardsoni | Yes | species | eukaryota | rodents | species | 111840 | click here |
| milvus migrans | Yes | species | eukaryota | vertebrates | species | 52810 | click here |
| miniopterus | Yes | | | mammals | genus | 9432 | click here |
| miniopterus fuliginosus | Yes | species | eukaryota | mammals | species | 187007 | click here |
| miniopterus gleni | Yes | species | eukaryota | mammals | species | 409372 | click here |
| miniopterus griveaudi | Yes | species | eukaryota | mammals | species | 568717 | click here |
| miniopterus inflatus | Yes | species | eukaryota | mammals | species | 221087 | click here |
| miniopterus magnater | Yes | species | eukaryota | mammals | species | 438766 | click here |
| miniopterus minor | Yes | species | eukaryota | mammals | species | 221086 | click here |