Q&A: Squid Matters

08 Oct, 2026

AUT Professor Kat Bolstad discusses deep-sea squid, their place in ocean ecosystems, the differences between giant and colossal squid and more.

Q: What is the AUT Squid Squad?

The AUT Squid Squad, properly known as the AUT Lab for Cephalopod Ecology and Systematics (ALCES), is a group of researchers who focus particularly on deep-sea squids. We look at their biodiversity, describe new species and work out how they fit into the marine ecosystems they inhabit. What is their role in the food chain? What interactions do they have with other animals? What are they doing down there in the dark?

Q: How and why did you become interested in being a squid researcher?

I have been interested in marine biology since I took a course in high school and did a project on anglerfish. At that time, I discovered how strange some of the biology is in the deep sea and was absolutely hooked on it.

Later, I worked at an aquarium, where I met an octopus for the first time. She was unlike any other animal I had encountered. She had a personality. She knew different human beings and seemed to enjoy interacting with people. From that point on, I knew cephalopods were the direction I needed to go in.

I moved to Aotearoa New Zealand in the early 2000s and met a researcher here who had done a lot of work on New Zealand octopuses. The researcher suggested that the biodiversity of squids in Aotearoa had a lot left to be discovered and put me on that research path. I have never looked back.

Q: Why are squid so important to ocean ecosystems?

It is hard for us to grasp just how many squid there are in the oceans. They form vital components of the food chain, and many marine animals eat or are eaten by cephalopods at some point in their life stages.

It is very difficult to estimate actual squid populations, but, as an example, sperm whales are likely to eat more than 300 million giant squid alone in a single year. That gives a general indication of how many there might be.

As humans overharvest other animals from the food chain, squid seem poised to fill those vacant niches. They are able to adapt rapidly to changing environmental conditions, and their populations can expand quite quickly. If we remove the large fishes from the ecosystem, we take away some of the squid's predators and competitors. As climate change continues, squid may become increasingly important in the world's ecosystems.

Q: How smart are squid?

Assessing animal intelligence is very difficult. We cannot ask them to take an IQ test or do a number of the other things we might use to test human intelligence.

Cephalopods live in all sorts of marine ecosystems, where they interact with different levels of complexity in the life and habitat around them. Squid tend to live in an open-water, three-dimensional environment. It is fairly stable. They have to be aware of their surroundings, but they do not have to deal with the kinds of complex habitats and ecosystems that octopuses do, for example.

We know that octopuses can do things such as learn to solve mazes and open jars, and sometimes even learn from each other. We do not have evidence of squid's ability to do that. If that is our benchmark for intelligence, I would have to say squid are not that high on the scale. They are very good at what they do, and we certainly would not survive well in the habitats where they live. In terms of behavioural complexity and computation, octopuses probably take the prize.

Q: What is the difference between a colossal squid and a giant squid?

They are both very large, and each holds the record for the largest squid in one sense or another. First, they come from completely different families. The family level is where we separate, for example, dogs, wolves, coyotes and foxes from cats, tigers, domestic cats and lions. That is how different giant and colossal squids are.

They also live in very different parts of the world. The colossal squid is found only in Antarctica. It is endemic to the Southern Ocean, whereas the giant squid is found in the deep sea of tropical and temperate oceans throughout the world and, as far as we are aware, not at the poles.

The giant squid is very long and slender. It can reach 13 metres, making it the longest invertebrate in the world. It is not as heavy as the colossal squid, which reaches seven metres and about 500 kilograms. The colossal squid is the heaviest invertebrate in the world.

They also have some very interesting differences. The colossal squid is powerfully built and has many sharp hooks on both its arms and tentacles. Some of those hooks can rotate a full 360 degrees in either direction, which is fascinating. The giant squid has very large suckers on the ends of its tentacles. Both the hooks and the suckers can leave scars on the heads of sperm whales. This is one piece of evidence that sperm whales feed on these very large squid.

A squid is never going to start that fight. It is not going to swim up to a sperm whale and pick that battle, but it certainly does not want to become dinner. There may be a struggle once the sperm whale realises the squid is there and decides to make a meal of it.

Q: You recently identified the first footage of a live colossal squid at home in the deep sea. Why is this discovery so exciting?

We have known about the colossal squid for 100 years. It was first described in 1925 from the stomach contents of a sperm whale. The remains were very large. They had hooks and were clearly not the same as any other type of squid we already knew about. It would then be a full century before we got the chance to see this animal at home, alive in the deep sea.

When we did, it was a baby. The research team happened to be diving down the water column to discover a new species at the seafloor. They came across a very beautiful little glass squid at about 600 metres in the water column. Looking closely at the footage, it was clear that it had the right features to be identified as a colossal squid for the first time.

This was our first glimpse of this animal, not shrivelled up in a jar or laid out as a giant corpse on a table in the lab. It was beautiful. It also allowed us to talk about the beauty and wonder of some of these deep-sea animals without having to deal with the Kraken hype or the stuff-of-nightmares monster tropes we get a lot with the deep sea.

Q: Could a squid the size of the mythical Kraken actually exist in the deep sea?

We are pretty sure we have not seen the absolute largest giant and colossal squids that are out there, because beaks found in predator stomachs tell us they do get a little larger than the largest specimens we have examined. So far, we do not have evidence of anything much, much larger than these two large species.

Q: Why are people so obsessed with the Kraken in pop culture?

People are fascinated by cephalopods of all sizes. The really big ones make great fodder for the imagination and great deep-sea movie monsters. You can have the tentacles waving wildly, pulling screaming sailors from ships into the water.

I think the fact that they are so different from us fuels people's imaginations. They do not have bones inside. Their eyes look very similar to ours, but we have no idea what is actually going on inside those heads.

Q: How much do we know about the deep sea?

We actually know quite a lot about it. Humans have been studying the deep sea for about 150 years. Before that, we were not sure if anything lived there at all. A huge amount of it has been explored, although we are still discovering things all the time and there is plenty left to do.

In some areas, we have very good mapping of the seafloor but have not had cameras down there to see exactly what is there. In other places, we have snapshots from imagery, but our maps still lag behind. We are still discovering new habitats, ecosystems and species all the time.

Q: What do you think ancient mariners actually saw when they talked about the Kraken?

Ancient mariners were often in pursuit of whales, such as the sperm whale, which eat these large squids and have been known to play with their food from time to time. It is very possible that mariners saw the remains of these large squids at the surface.

Sperm whales have also often been seen playing with things such as bull kelp at the surface. It is very large and dark and looks a bit like the arms of a large squid. If it gets thrown through the air, there could be a resemblance.

It is worth bearing in mind that ancient mariners, much like modern fishers, love to tell a good tall tale and exaggerate the size of things. Depending on the grog rations that day, those stories could get even wilder.

Q: Could a squid hurt a human?

There are species of squid that interact with humans in the water. The Humboldt squid, or jumbo squid, in the Eastern Pacific is famously said to be aggressive, certainly curious, and is a large predator that travels in groups. Divers who interact with these animals sometimes wear chainmail to avoid being bitten or, if bitten, to reduce the severity of the bite.

Most species of squid would never naturally come across humans, so it is very unlikely. A healthy giant squid is never going to be at the surface of the ocean, and you are unlikely to be swimming in the Antarctic with a colossal squid. Unless you are purposely getting in with Humboldt squid and taking matters into your own hands at your own risk, you are very unlikely to be hurt by a squid.

However, we think all cephalopods have some kind of venom. If you are handling an octopus, a cuttlefish or a broad squid and get bitten, you may experience adverse effects, depending on the species, ranging up to lethal effects, as with the Australian blue-ringed octopus.

Q: How many types of squid are there?

There are probably about 900 species of cephalopods, including octopuses, cuttlefishes, squids and their relatives. The answer to how many squid there are depends on exactly where we draw the line around squid, because a couple of different groups are commonly referred to as squid.

For example, the vampire squid has a great name, but it is wildly inaccurate: it is not a squid at all and is not a vampire. If we are strictly talking about animals we would classify within the main groups as squid, there are somewhere between 300 and 400 species.

Q: Are any species unique to New Zealand or Antarctic waters?

In the Antarctic in particular, most species of cephalopod are endemic, so are found only in that habitat, or at least in the Southern Ocean. We also have a handful of endemic octopus and squid species in Aotearoa New Zealand.

Q: What are your thoughts on octopus farming?

I primarily study deep-sea squid, but I work within a research community of people who are very knowledgeable about cephalopod welfare. Most people who research cephalopod welfare feel that octopus farming cannot be done in an ethical and humane way at this stage.

Q: Would you ever eat squid or octopus?

I would not eat octopus. I used to eat calamari, before I knew more about how these animals tend to be caught and the impact that can have on their populations and ecosystems.

Q: What is your favourite cephalopod in pop culture?

I have to give a couple of different shout-outs. I have children, so of course I love Professor Inkling in the Octonauts series. Hank the octopus from Finding Dory was fantastic. I thought Davy Jones from Pirates of the Caribbean was extremely well done, too.

I probably have to credit some of my life's direction to having watched 20,000 Leagues Under the Sea as a fairly young child. I think I first saw the film at about age seven. Interestingly, the way they did the giant squid, even in the 1950s, holds up pretty well and certainly better than some other representations in film.

I was so fascinated by it that I made myself a paper doll of Captain Nemo, covered in giant squid suckers, and the rest is history.

Useful links:

Professor Kat Bolstad's academic profile

The ALCES AUT 'Squid Squad'