| martes martes | Yes | species | eukaryota | mammals | species | 29065 | click here |
| martes pennanti | Yes | species | eukaryota | mammals | species | 76720 | click here |
| mastomys erythroleucus | Yes | species | eukaryota | rodents | species | 41268 | click here |
| mastomys natalensis | Yes | species | eukaryota | rodents | species | 10112 | click here |
| mastomys sp. | Yes | no rank | eukaryota | rodents | species | 70830 | click here |
| mastotermes darwiniensis | Yes | species | eukaryota | invertebrates | species | 13139 | click here |
| maxomys surifer | Yes | species | eukaryota | rodents | species | 69081 | click here |
| maxomys whiteheadi | Yes | species | eukaryota | rodents | species | 69127 | click here |
| mazama americana | Yes | species | eukaryota | mammals | species | 43334 | click here |
| mazama gouazoupira | Yes | species | eukaryota | mammals | species | 52407 | click here |
| mazama nana | Yes | species | eukaryota | mammals | species | 397613 | click here |
| meleagris gallopavo | Yes | species | eukaryota | vertebrates | species | 9103 | click here |
| meleagris gallopavo intermedia | Yes | subspecies | eukaryota | vertebrates | subspecies | 109972 | click here |
| meleagris gallopavo silvestris | Yes | subspecies | eukaryota | vertebrates | subspecies | 109974 | click here |
| meles meles | Yes | species | eukaryota | mammals | species | 9662 | click here |
| melophagus ovinus | Yes | species | eukaryota | invertebrates | species | 452749 | click here |
| melospiza georgiana | Yes | species | eukaryota | vertebrates | species | 44398 | click here |
| melospiza melodia | Yes | species | eukaryota | vertebrates | species | 44397 | click here |
| mephitidae | Yes | | | mammals | family | 119825 | click here |
| mephitis mephitis | Yes | species | eukaryota | mammals | species | 30548 | click here |
| meriones persicus | Yes | species | | | species | 1395794 | click here |
| meriones unguiculatus | Yes | species | eukaryota | rodents | species | 10047 | click here |
| mesocricetus auratus | Yes | species | eukaryota | rodents | species | 10036 | click here |
| mesomys hispidus | Yes | species | eukaryota | rodents | species | 30627 | click here |
| metachirus nudicaudatus | Yes | species | eukaryota | mammals | species | 42725 | click here |
| methanosarcina mazei | Yes | species | archaea | bacteria | species | 2209 | click here |
| micoureus demerarae | Yes | species | eukaryota | mammals | species | 42719 | click here |
| micoureus regina | Yes | species | eukaryota | mammals | species | 42720 | click here |
| microcerotermes | Yes | | | invertebrates | genus | 139992 | click here |
| microcerotermes parvus | Yes | species | eukaryota | invertebrates | species | 187517 | click here |
| microdon dimorphon | Yes | species | eukaryota | invertebrates | species | 115311 | click here |
| microgale cowani | Yes | species | eukaryota | mammals | species | 329863 | click here |
| microgale dobsoni | Yes | species | | | species | 1206715 | click here |
| microgale drouhardi | Yes | species | | | species | 1833851 | 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 talazaci | Yes | species | eukaryota | mammals | species | 176115 | click here |
| micromys minutus | Yes | species | eukaryota | rodents | species | 13151 | click here |
| microtermes | Yes | | | invertebrates | genus | 201585 | click here |
| microtus | Yes | | | rodents | genus | 10053 | click here |
| microtus agrestis | Yes | species | eukaryota | rodents | species | 29092 | click here |
| microtus arvalis | Yes | species | eukaryota | rodents | species | 47230 | click here |
| microtus californicus | Yes | species | eukaryota | rodents | species | 100895 | click here |
| microtus californicus scirpensis | Yes | subspecies | eukaryota | rodents | subspecies | 717895 | click here |
| microtus fortis | Yes | species | eukaryota | rodents | species | 100897 | click here |
| microtus lusitanicus | Yes | species | eukaryota | rodents | species | 184258 | click here |
| microtus montebelli | Yes | species | eukaryota | rodents | species | 79202 | click here |
| microtus ochrogaster | Yes | species | eukaryota | rodents | species | 79684 | click here |
| microtus oeconomus | Yes | species | eukaryota | rodents | species | 64717 | click here |
| microtus pennsylvanicus | Yes | species | eukaryota | rodents | species | 10058 | click here |
| microtus socialis | Yes | species | eukaryota | rodents | species | 269658 | click here |
| microtus subterraneus | Yes | species | eukaryota | rodents | species | 137712 | click here |
| mimon crenulatum | Yes | species | eukaryota | mammals | species | 148071 | click here |
| miniopterus | Yes | | | mammals | genus | 9432 | click here |
| miniopterus gleni | Yes | species | eukaryota | mammals | species | 409372 | click here |
| miniopterus griffithsi | Yes | species | eukaryota | mammals | species | 666442 | click here |
| miniopterus griveaudi | Yes | species | eukaryota | mammals | species | 568717 | click here |
| miniopterus majori | Yes | species | eukaryota | mammals | species | 409373 | click here |
| miniopterus natalensis | Yes | species | eukaryota | mammals | species | 291302 | click here |
| miniopterus schreibersii | Yes | species | eukaryota | mammals | species | 9433 | click here |
| miniopterus sororculus | Yes | species | | | species | 947061 | click here |
| miniopterus sp. 1 bra-2013 | Yes | no rank | | | species | 1434095 | click here |
| miniopterus sp. bbra-2009d | Yes | no rank | eukaryota | mammals | species | 647620 | click here |
| mirounga angustirostris | Yes | species | eukaryota | mammals | species | 9716 | click here |
| mirounga leonina | Yes | species | eukaryota | mammals | species | 9715 | click here |
| molossus currentium | Yes | species | | | species | 1269259 | click here |
| molossus molossus | Yes | species | eukaryota | mammals | species | 27622 | click here |
| molossus rufus | Yes | species | eukaryota | mammals | species | 124751 | click here |
| monodelphis glirina | Yes | species | eukaryota | mammals | species | 943244 | click here |
| monodelphis peruviana | Yes | species | eukaryota | mammals | species | 372564 | click here |
| montastraea annularis | Yes | species | eukaryota | invertebrates | species | 48500 | click here |
| montastraea faveolata | Yes | species | eukaryota | invertebrates | species | 48498 | click here |
| mormopterus acetabulosus | Yes | species | eukaryota | mammals | species | 525717 | click here |
| mormopterus jugularis | Yes | species | | | species | 999964 | click here |
| mormopterus sp. bbvv-2008 | Yes | no rank | eukaryota | mammals | species | 524134 | click here |
| mungos mungo | Yes | species | eukaryota | mammals | species | 210652 | click here |
| muntiacus reevesi | Yes | species | eukaryota | mammals | species | 9886 | click here |
| mus | Yes | | | rodents | genus | 10088 | click here |
| mus caroli | Yes | species | eukaryota | rodents | species | 10089 | click here |
| mus cervicolor | Yes | species | eukaryota | rodents | species | 10097 | click here |
| mus cookii | Yes | species | eukaryota | rodents | species | 10098 | click here |
| mus musculus | Yes | species | eukaryota | rodents | species | 10090 | click here |
| mus musculus domesticus | Yes | subspecies | eukaryota | rodents | subspecies | 10092 | click here |
| mus pahari | Yes | species | eukaryota | rodents | species | 10093 | click here |
| mus sp. | Yes | no rank | eukaryota | rodents | species | 10095 | click here |
| mussismilia | Yes | | | invertebrates | genus | 242720 | click here |
| mustela | Yes | | | mammals | genus | 9665 | click here |
| mustela lutreola | Yes | species | eukaryota | mammals | species | 9666 | click here |
| mustela putorius | Yes | species | eukaryota | mammals | species | 9668 | click here |
| mustelidae | Yes | | | mammals | family | 9655 | click here |
| myocastor coypus | Yes | species | eukaryota | rodents | species | 10157 | click here |
| myodes gapperi | Yes | species | eukaryota | rodents | species | 473866 | click here |
| myodes glareolus | Yes | species | eukaryota | rodents | species | 447135 | click here |
| myodes rufocanus | Yes | species | eukaryota | rodents | species | 527686 | click here |
| myodes rufocanus bedfordiae | Yes | subspecies | eukaryota | rodents | subspecies | 36236 | click here |
| myodes rutilus | Yes | species | eukaryota | rodents | species | 537920 | click here |
| myotis | Yes | | | mammals | genus | 9434 | click here |
| myotis adversus | Yes | species | eukaryota | mammals | species | 59461 | click here |
| myotis adversus taiwanensis | Yes | subspecies | eukaryota | mammals | subspecies | 867861 | click here |