Editing Atlantic Ocean (section)

=== Sargasso Sea ===
{{Main|Sargasso Sea}}
{{Multiple image
 | image1 = Sargasso.png | caption1 = Approximate extent of the Sargasso Sea
 | image2 = HanaOZ.jpg | caption2 = Sargassum fish (''Histrio histrio'')
}}
The Sargasso Sea in the western North Atlantic can be defined as the area where two species of ''[[Sargassum]]'' (''S. fluitans'' and ''natans'') float, an area {{cvt|4000|km}} wide and encircled by the [[Gulf Stream]], [[North Atlantic Drift]], and [[North Equatorial Current]]. This population of seaweed probably originated from Tertiary ancestors on the European shores of the former [[Tethys Ocean]] and has, if so, maintained itself by [[Vegetative reproduction|vegetative growth]], floating in the ocean for millions of years.<ref name="Lün-p223">{{Harvnb|Lüning|1990|pp=223–225}}</ref>

Other species endemic to the Sargasso Sea include the [[sargassum fish]], a predator with algae-like appendages which hovers motionless among the ''Sargassum''. Fossils of similar fishes have been found in fossil bays of the former Tethys Ocean, in what is now the [[Carpathian Mountains|Carpathian]] region, that were similar to the Sargasso Sea. It is possible that the population in the Sargasso Sea migrated to the Atlantic as the Tethys closed at the end of the Miocene around 17&nbsp;Ma.<ref name="Lün-p223" /> The origin of the Sargasso fauna and flora remained enigmatic for centuries. The fossils found in the Carpathians in the mid-20th century often called the "quasi-Sargasso assemblage", finally showed that this assemblage originated in the [[Carpathian Basin]] from where it migrated over [[Sicily]] to the central Atlantic where it evolved into modern species of the Sargasso Sea.<ref>{{Harvnb|Jerzmańska|Kotlarczyk|1976|loc=Abstract; Biogeographic Significance of the "Quasi-Sargasso" Assemblage, pp. 303–304}}</ref>

The location of the spawning ground for [[European eel]]s [[Eel life history#Search for the spawning grounds|remained unknown for decades]]. In the early 19th century it was discovered that the southern Sargasso Sea is the spawning ground for both the [[European eel|European]] and [[American eel]] and that the former migrate more than {{cvt|5000|km}} and the latter {{cvt|2000|km}}. Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and northern Africa.<ref>{{Harvnb|Als|Hansen|Maes|Castonguay|2011|p=1334}}</ref> Recent but disputed research suggests that eels possibly use [[Earth's magnetic field]] to navigate through the ocean both as larvae and as adults.<ref>{{Cite web|url=https://www.scientificamerican.com/article/do-baby-eels-use-magnetic-maps-to-hitch-a-ride-on-the-gulf-stream/|first1=Andrea|last1=Marks|title=Do Baby Eels Use Magnetic Maps to Hitch a Ride on the Gulf Stream?|date=17 April 2017|website=Scientific American|url-status=live|archive-url=https://web.archive.org/web/20170419192009/https://www.scientificamerican.com/article/do-baby-eels-use-magnetic-maps-to-hitch-a-ride-on-the-gulf-stream/?WT.mc_id=SA_EVO_20170417|archive-date=19 April 2017|access-date=18 April 2017}}</ref>