Silvery bryum moss (Bryum argenteum) and redshank (Ceratodon purpureus) are two plants: https://link.springer.com/article/10.1007/s00300-014-1537-3
Tardigrades. Even in Antarctica. Tough little buggers.
Galerina marginata (Funeral Bell Mushroom) I think. Fairly cosmopolitan and was somewhat recently found in antarctica too
If correctly ID’d, than Elegant Sunburst Lichen in found in every continent
When it comes to fungi then I think care is needed in interpreting the evidence. Current phylogenetic data indicate at least 3 distinct taxa under the name Galerina marginata. One appears to be distributed across Europe and the (eastern?) USA, another across Asia and (western?) USA and a third in Australasia. This is the usual picture for fungi, where traditional morphological specie concepts often don’t uniquely match phylogenetic concepts. So the potential global distribution of a ‘species’ depends highly on what you define as a species.
I think it would be even more interesting to break it down to those that have breeding populations on every continent.
Tardigrades cheat though…they’re a phylum. Like vertebrates.
Polytrichum juniperinum, or Juniper Haircap Moss.
They do not naturally occur there.
There are over a thousand different species of tardigrade, though. They would only count if there was a single species of Tardigrade that is found everywhere, which I think is very doubtful.
There is at least one arachnid species found on every continent: Ixodes uriae. They are generalist ticks that parasitize a wide variety of seabirds that nest in colder regions, including penguins, auks, albatrosses, petrels, gulls, and more. They are found in the northern regions of the US, Canada, Europe, Russia, and Japan, and the southern regions of Chile, Argentina, South Africa, Australia, and New Zealand, as well as coastal parts of Antarctica and subantarctic islands.
LOTS of foraminifera species have completely global distributions. Trochammina inflata, for example, is known from Antarctica ( https://www.sciencedirect.com/science/article/pii/S235248551830166X), Australasia (https://www.bing.com/search?q=new+zealand+shallow+water+benthic+foraminifera&cvid=0fb0d6666f89426fbc802a4e303a6499&aqs=edge.0.69i59j0l8.11602j0j4&FORM=ANAB01&PC=LCTS), Europe, Asia, and the Americas (https://www.researchgate.net/publication/322661225_The_salt_marsh_foraminifer_Trochammina_inflata_with_a_distinct_morphotype_in_the_White_Sea_a_local_variety_or_new_subspecies), and from Africa (https://oceanrep.geomar.de/id/eprint/32867/)
I’m not sure about a single species, but the fly family Chironomidae are the only flies found on every continent, including Antarctica.
Well, there is only one higher plant species that can be found on all continents as far as I know: Poa annua
This species is very interesting, it is an allotetraploid species resulting from the crossing of Poa infirma x Poa supina and can now be found all over the world, including Antarctica.
Some other species such as Poa pratensis, Trifolium repens, Veronica serpyllifolia, Achillea millefolium, Prunella vulgaris, Plantago lanceolata, Plantago major, Ranunculus repens or Taraxacum officinale are not far from global distribution. Due to climate change and increasing Antarctic tourism, they could also become part of the Antarctic flora in the longer term, to the detriment of the ancient lichen and moss communities native there.
Cetaceans are probably your best bet for this - Orca has already been mentioned, but Humpback Whale, Blue Whale and Sperm Whale (and perhaps others) also can be found on every continent
@mrdanieljking Welcome to the forums :-)
Unfortunately this is increasingly the response to many issues or concerns , and we still don’t know enough about so many places to begin to even have local strategies.
Rhizocarpon geographicum (I just checked on iNat) and probably other lichens
Several springtail species are highly cosmopolitan, and have been recorded regularly on every continent including Antartica. Isotoma viridis is one that comes to mind (though note that iNat distribution data is extremely incomplete, owing to the small number of springtail observers and even smaller number of people who are able to ID them to species on iNat). I think many hypogasturids (or snow fleas) also have been recorded globally. There’s almost certainly many more that are truly, globally cosmopolitan that have simply not been officially recorded to species.