Cross Breeds

How do animals in the deep ocean find their way around?

I've noticed that alot of the species down there in the blackness (mostly predatory animals) have eyes. I was wondering: why would they all have these massive eyes if no light gets down there? What other senses do animals down there use to find prey?

Public Comments

1. Sonar..
2. some make their own light, but not really sure
3. Yes you're right: most animals in the deep ocean have eyes. Although there is not natural light, many species of fish and marine invertebrates can produce light in their bodies. I saw it in a lot of documentaries. Take in mind that many animals are in the deep ocean only for a short time. So they need eyes for see in the surface. Some species like the sperm whale use their sonar for locating food.
4. "Bioluminescence is a form of luminescence, or "cold light" emission; less than 20% of the light generates thermal radiation. It should not be confused with fluorescence, phosphorescence or refraction of light. Ninety percent of deep-sea marine life is estimated to produce bioluminescence in one form or another." If that is the case, then having eyes is definitely an advantage in the deep sea.
5. Deep sea fish tend to move very slowly to conserve energy since there is a general lack of food. From what I understand they use their eyes mainly for reproductive purposes. I am sure you have seen the glowing (bioluminescent) probes and stuff on some of them. This is used in conjunction with chemical pheromones to attract mates. However this can also be used for hunting and tricking prey to approach and thus get eaten. Almost all fish have a sensory system called the lateral line system which detects pressure changes, turbulence, etc. Sharks tend to have electrical sensory cells that detect the faint electrical field generated by prey. Mainly though most animals down there probably rely on their sense of smell to find food.
6. I'm not sure.But they can see somehow.Just like at night sometimes domesticated cat's eyes glow,that's how they see.