Mummichog

• It withstands salinities from fresh water to twice that of the sea, and temperature swings of more than thirty degrees over the year.
• Populations living in heavily polluted industrial estuaries have developed, within a few decades, genetic resistance to toxic compounds that would kill individuals from clean areas — one of the best-documented cases of rapid evolution in a vertebrate.
• It travelled into space on the Skylab 3 mission in 1973 to study how fish orient themselves in the absence of gravity.
• It is one of the most tolerant vertebrates in existence: it withstands extreme changes in salinity, temperature and oxygen, which has made it a classic model in comparative physiology.
• It was the first fish to travel into space: specimens were taken up on the Skylab programme in 1973 to study how they orient themselves without gravity.
• Some populations in heavily polluted estuaries have evolved genetic resistance to PCBs and dioxins within a few decades. It is one of the best-documented cases of rapid evolution in response to pollution.
• That resistance arose independently in several different estuaries, from genetic variants that were already present in the population.
• It is called the mummichog, a name of Algonquian origin that means roughly "they go in crowds".

Skeleton type

Vertebrate - internal bony skeleton (fish)

Habitat and environment

Brackish marshes, creeks and tidal pools of the Atlantic coast of North America

Sources consulted: Wikipedia (es): Fundulus heteroclitus

The pins mark the parks where its presence is documented.