A FISHY STORY

Two hundred million years ago, all of the continents of the southern hemisphere were connected as part of a supercontinent called Gondwana. The ancestors of many animals and plants could move from one part of this landmass to another until it began to split into different pieces.

Most freshwater fish cannot survive for an extended period of time in salt water, so it's difficult for them to swim across oceasn and become established on islands. Scientists believe that the ancestors of Madagascar's freshwater fish species were swimming in what are now Madagascar's rivers and lakes before Gondwana separated into different continents.

All the freshwater fish of Madagascar are endemic, unique species found nowhere else on earth. Though no other country has the exact same kinds of fish, some distant places have fishes that are very closely related to those on Madagascar.

In this activity, you'll collect freshwater fish from all the different continents that make up Gondwana and put them into charts called cladograms that show their relationships to one another.