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Why did it take so long to obtain photographic and video evidence of live Architeuthis?
Question Date: 2019-10-28
Answer 1:

Giant squids are amazing animals. For a long time, we only knew of the species because of dead ones that would wash up on beaches.

To understand why it took so long to get video of live ones, it's important to understand more about where they live. Giant squids live deep in the ocean. They're usually well below where the light can penetrate. When you consider how enormous the ocean is, and how deep it is, it's almost more amazing that we have footage now.

Consider that there's about 3 times more ocean than land mass. And the ocean is a three-dimensional environment. There are places in the ocean where you could drop Mount Everest in and still have it fall far below the surface. That's a lot of volume to look around in, especially in the dark. Also consider how difficult for humans to ever go very deep in the ocean. Submarines can't really go that deep before the water pressure would crush them. (If you have ever seen a submarine movie, you have probably seen a sequence where the sub is at the limit of its depth and everyone is afraid that it will be destroyed by the pressure.) Special diving vehicles can deeper, but every trip is very expensive and can only cover a tiny area. The use of remote-controlled vehicles allows us to see more.

There probably aren't all that many giant squids to find, either. They eat deep sea fish. Those fish probably eat other animals. But the deep sea is a sort of food desert. The source of almost all energy on earth is the sun. Plants, algae, and other producers use photosynthesis to turn light energy into food energy. The producers in the ocean are called "phytoplankton." They are tiny. Obviously, they can only do photosynthesis up in the zone where the light is. They also need nutrients like nitrogen, phosphorus, and such, which are the building blocks of molecules like proteins, fats, and carbohydrates. Unfortunately for them, nutrients fall down through the water due to gravity. So productivity (the amount of photosynthesis that can happen) is quite low compared to what can happen in a shallow, nutrient-rich lake.

Only a fraction of the energy in the phytoplankton makes it into their predators, the zooplankton. The rest is used by the phytoplankton to power their own work. Zooplankton are tiny shrimp-like animals that live up in or near the light zone where their prey are. The fish and other animals that eat zooplankton only get a fraction of the energy that was in their prey. Each time you go up one layer of the food (or trophic) pyramid, there are fewer individuals and less biomass (mass of living things).

Down at the bottom of the ocean, the food pyramid is mostly based on dead things that sank down from higher up. This means there's not much food to support even the lowest levels of the food pyramid. Giant squid have to travel huge distances to find enough food. Think about how big giant squid are. Females can be 13 meters long, while males can be 10 m long. A squid can be over 600 pounds (275 kg). So it would take an enormous area to support enough fish to feed it. Even if you could magically see them from the surface, you'd have to search a lot of area to find one.

If you're wondering why I said "almost all energy on earth comes from the sun," look at some information on the hydrothermal vents in the deep ocean that supports life based on hydrogen sulfide, here .

Why do you think a blue whale (the largest animal on earth) eats tiny zooplankton?

Thanks for asking,

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