Cool fish!
- Flounders: “Baby flounders look like any other normal fish, swimming upright with one eye on each side. Then, in preparation for adult life, they undergo a bizarre transformation: one eye migrates to the other side of the face. It’s like facial reconstructive surgery, only in slow motion, and without scalpels and sutures. It isn’t even always slow. The entire migration takes just five days if you’re a starry flounder, and less than one day in some species.“
- Four-eyed fish: “…these relatives of the guppy sport a discrete demarcation between the upper and lower portion of their retina. The fish swims so that the demarcation aligns exactly with the plane of the water surface, the airborne portion of the eyes providing ideal air vision while the submerged portion accommodates the aquatic medium. Flexible genetic coding makes the upper eyes sensitive to green-light wavelengths that predominate in air, and the lower eyes more sensitive to the yellow wavelengths found in muddy waters.”
- ”Swordfishes can heat up their eyes twenty to thirty degrees Fahrenheit above the water temperature. The heat is generated by a countercurrent exchange between the incoming and outgoing blood vessels surrounding the eye muscles. Arteries bringing cold blood from the heart and veins are warmed by a special heat-generating organ in one of the eye muscles. These arteries form a tight, latticed network, enhancing the exchange of heat between them.”
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Frillfin goby: Memorizes locations of where tide pools will be at low tide while swimming over them at high tide; then, when in one pool at low tide, can leap into another one over dry land to escape predators! Example of cognitive mapping.
- Color vision likely first evolved underwater — also, most modern bony fishes are tetrachromatic!!
- Fish have very sensitive senses of hearing, smell, taste
- Navigation via sensing magnetic field, with single cells containing magnetic particles that may cause the cell itself to rotate, activating stress-sensitive transducers; also via smell— ex. salmon “record” the water chemistry along migratory routes and follow this path back
- Pressure sensing (to coordinate schooling!) by neuromast cells in lateral line, have hairlike projections encased in gel -> sense changes in water turbulence, pressure
- Electroreception— almost unique sense to fish (besides platypuses, bees, echidnas); sensed by jelly-filled pores called ampullae of Lorenzini
- Consciousness, too, likely evolved first in fish