I just walked the dock in Kodiak. There were the usual working boats and a couple of sailboats. I noticed that some of the fishing vessels were rather fat-looking, whereas the sailboats were slender. Close to the sunlit water surface I saw a few small fish. Actually, I could only see their outlines, narrow and long and pointed at both ends, kind of like the sailboats. Is it coincidence or design?
On our boat tour today, we lowered a fishing line in the water and pulled out a couple of small, black rockfish and a beautiful female kelp greenling with bright yellow pectoral fins and orange spots. After showing them off all fish were released and swam away to live another day.
Both of these species have the same slender hull as the sailboats. Their anal fins even function like the keel of a boat. However, several times this summer the fish on the hook looked very different, perhaps more like a flatbottom river boat. Those were rock soles, one of over 700 species of flatfish worldwide.
There are 11 families of flatfish. All their 700 species have in common that they are dorso-ventrally flattened, the scientific way of saying they are flat like a pancake. They all live at the bottom of the ocean, where they either lay motionless or travel.
The most striking feature of flatfish is that they are asymmetric. They have one pectoral fin on top and one on the bottom side, their mouth opens sideways instead of up and down, their backside is colored differently than their tummy, and they are cockeyed.
Every one of these fish starts out as an egg and hatches as a tiny larva that rides the currents as part of the plankton community. Slowly using up its eggyolk sac and learning to catch other tiny plankton organisms, the flatfish larva grows bigger. At this time it swims upright with an eye on each side of the head looking much like a tiny version of Dory in “Finding Nemo,” except for the colors.
When our little flatfish gets to the size of a dime it looks for a tidal flat area or river delta with small creeks or puddles to feed and grow. As the larva settles from the lifestyle in the plankton to living on the bottom, it lays down on one side and a most miraculous transformation takes place. The eye that would now be looking down begins to migrate over the fish’s head to the other side.
When evolution puts major changes in the design of an animal, scientists often don’t have any clues about how this change happened. In the case of the flatfish they got lucky when in 2008 a 50 million-year-old fossil of an early flatfish was found with the right eye on top of the head. This is considered a transitional species, one where the migration of the eye had not yet been completed.
The rock soles we caught sometimes ended up as dinner. With a filet to the left and right of the spine and one on the dorsal (back) and another on the ventral (belly) side, there are four small filets, which make just enough for one person. I only add a little lemon juice, salt and pepper and fry them briefly in butter. I leave the skin on for frying but do not eat it.
With a fresh salad this is a healthy and extremely delicious meal, which may be enjoyed with some background rock soul, which is a style of music.