Albacore Flies


Active Member
Right, but I don’t think fish pupils contract like ours can? In which case you’d think a denizen of the deep would have a larger pupil? I’m out of my depth here.
Out of your depth? Pfft! You're a professional fish nerd, I just play one on the internet.. which is where I just stole another pic showing a larger pupil.



Sculpin Enterprises
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That is a great picture of a lanternfish. Those silvery dots below the lateral line, especially along the ventral edge of the body, are photophores - light-producing organs. The photophores along the ventral side of the body produce a diffuse light that acts as counter-illumination; it matches the intensity of downwelling light and removes the dark underside of the fish when viewed by a predator that is below the lanternfish. The number and location of lateral photophores differ between males and females of the same species and between species and may play a role in mate attraction and species recognition.
Lanternfishes form a major part of the vertically-migrating fauna that spends the middle of the day at deeper depths and then migrates to the surface to feed at night. Lanternfish do appear in the diet of albacore tuna but I wonder if that pattern varies on a lunar schedule. During a new moon, there may not be enough light for albacore to attack lanternfish successfully when they are at the surface at night. But during a full moon, there may be enough light for albacore to feed extensively on lanternfish and other vertically-migrating prey.
P.S., While elasmobranchs can change their pupil size by dilating / constricting the iris, most bony fish cannot.
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