Fishes do much more than swim! Some fishes cling to rocks so they don’t get pushed around by waves and currents. Others fly through the air so get away from predators. But the #BestFish (in my unbiased professional opinion) climb waterfalls! My name is Kelly Diamond, and currently I am a PhD candidate in Rick Blob’s lab. I study how waterfall-climbing fish called gobies migrate from the ocean to freshwater habitats.
Goby fishes are one of the largest groups of fishes in the world (currently 1842 species!). Most of these species live their whole lives in the ocean. But some species migrate from the ocean to freshwater streams, where they live as adults. This type of life cycle is called amphidromy. The Hawaiian name for these fish is o’opu (pronounced oh-oh-poo). There are five species of o’opu found only in Hawaii (lucky fish I know!) In early spring the baby o’opu, or hinana (hin-na-nah), migrate from the ocean upstream to freshwater habitats.
There are 2 measures of performance we collect from these hinana. The first is escape performance because hinana must avoid other fish trying to eat them! To measure escape performance we simulate a predator attack. These fish use their lateral line system (a series of pores along the body) to detect differences in water flow caused by the predators. The lateral line system in the water is analogous to the hair on our bodies. We can tell which direction a breeze is blowing because the wind hits the hairs on one side of the body slightly before the hairs on the other side of the body. The pores on the body of a fish work the same way as our hairs! We simulate an escape response by squirting a jet of water at the fish, which they think is a predator. We record their responses with high speed video! From these videos we can measure a bunch of things, including how fast the fish escapes and at what angle.
— Kelly Diamond (@DiamondKMG) December 14, 2017
The other measure of performance we collect is climbing performance. These fishes climb waterfalls as part of their life cycle! To measure climbing performance we have made artificial waterfalls! One waterfall is Plexiglas (to record the belly side of the fish), the other is a rain gutter (to record the back side of the fish). We record the fish climb and measure how fast the o’opu climb.
SERIOUSLY LOOK AT THIS WATERFALLS (OK PLEXIGLASS) CLIMBING GOBY FISH! pic.twitter.com/XWtYs8EQhc
— Kelly Diamond (@DiamondKMG) March 26, 2019
This year we had three major projects we were working on. The first looks at how performance may differ among the Hawaiian islands. The second examines how water temperatures may influence performance. For the third, we measured how performance may change of the course of the migration period. For updates on all these projects stay tuned, and check out my website or follow me on twitter (@DiamondKMG)!
Outside of data collection, working in Hawaii has some major perks! The weather is wet but warm! The field sites are beautiful! There are some great hikes to explore in the evenings! And as a #HERper (a lady that likes to search for reptiles and amphibians) there is always something fun to do in our free time!
Thanks for the read! I love talking with people about fishes (especially gobies) and science in general. Please fell free to reach out if you have any questions or just want to chat about some cool fish!