What’s inside the Squid Cube?

In a containment lab in Wellington, New Zealand, Kat Bolstad considered the squid cube. It was the size of a barrel and had been frozen over since January, when it was carried during a trawl survey of fishing grounds in the east of the country. The squid cube was not a squid cube, but rather a single cube-shaped squid whose flabby body had been folded into a rectangular fish box and later stored in a freezer. It chilled there until June, when Bolstad, a deep-sea squid biologist at the Auckland University of Technology, was ready to unpack it.

“It’s not the first squid cube,” said Bolstad, who has seen many cubes of varying sizes and species in his line of work. But it was certainly a very special squid cube, comprising the carefully pleated body of an entire giant squid, signifying a species of deep-sea squid in the family. Architeuthidae. When giant Giant squid are caught in research trawl nets, their bodies are too big to be diced, i.e. stored whole in a standard 50 liter crate. These true giants are usually frozen in pieces or “whole, in a gigantic kind of very large sausage-shaped package that needs to be moved by a forklift,” Bolstad said. But this giant squid, a young female, was small enough to fit inside the fish box and become a cube of its own. As Bolstad described the arrangement of the squid’s body: “It was like a cat curled up to take a nap inside the fish box.”

About twice a year, Bolstad’s lab goes to Wellington to thaw cubes of squid and other squid (frozen squid that bear less resemblance to regular geometric shapes). The city is home to the marine collection facilities of the National Institute for Aquatic and Atmospheric Research, or NIWA, which slowly accumulates and freezes creatures collected on the institute’s research cruises. Some of the squid are frozen for months before their dead flesh experiences the heat again. And the quality of the carcasses can vary greatly depending on the squid’s journey from the bottom to the surface. “Sometimes you get a really nice one,” Bolstad said. “Sometimes it feels like someone sneezed on a tray.”

Credit: Kat Bolstad
This big chiroteuthiswhich has exceptionally long arms, is what would be considered a “beautiful” specimen.

Successfully unpacking frozen squid can be a race against time: the Bolstad lab and NIWA employees must complete their work before the meat starts to rot. While a single finger-sized squid can thaw in half an hour, larger squid can take a full day. And a squid packed into a cube also doesn’t thaw evenly, running the risk that the outside of the cube could rot while the inside is still frozen. A few years ago, Bolstad had to thaw a cube of colossal squid – a completely different species, and the largest invertebrate on the planet – weighing over 450 kilograms. Colossal squid tissue is more delicate than giant squid tissue, so Bolstad’s team thawed that colossal cube in a bath of sea ice to keep the dead squid in relatively pristine conditions.

The June squid cube was less demanding, thawing in mid-air overnight until researchers came back to unfold the half-thawed cube and run water over its body to help it. “We had visions of it, like, unfolding and then sliding to the ground and having a horrible disaster in the morning,” Bolstad said. But the squid cube cooperated and the next day it could be fully unrolled and restored to its 20-foot-long tentacled glory.

The formerly cube-shaped giant squid, totally boxless.

Scientists don’t usually get a chance to examine giant squid. The animals are very large and live in waters thousands of meters deep, making it quite unpredictable when one might appear. For a long time, scientists could only study Architeuthis of squid that were found dead on the beach, dead in the water, or were digested or regurgitated by sperm whales, according to a 2013 article in the journal American Malacological Bulletin. Recent advances in deep-sea trawling systems and underwater cameras have given scientists a little more access to the elusive giants.

Still, it’s rare to find a giant squid that hasn’t reached full size, Bolstad said. Scientists are still investigating the life cycle of the giant squid, a cephalopod whose childhood is something of a black box. “There’s a size below which specimens are basically unknown,” Bolstad said, adding that there are records of “pretty small” mature males. But female giant squids get much larger: while a mature male can reach around 32 feet, a mature female can grow to 42 feet. Mature male giant squid produce sperm packets called spermatophores and implant them in the skin of a female giant squid. But the researchers found only tiny hints of eggs in this particular cube squid, meaning it was an immature female that hadn’t mated.

Curious as to what she ate, the team at Bolstad gently slid the squid’s innards out. This week, the researchers plan to thaw the squid’s innards — which unfortunately are not cube-shaped, but roughly oblong — and examine what semi-digested creatures and undigested microplastics might hide inside. With any luck, they will find some parasites. Many parasites in the ocean have to pass through different unique hosts throughout their life cycle: after being expelled by a fish, they may have to penetrate a snail and perhaps a mollusk before being eaten by another fish. Finding a parasitic worm in a giant squid could help scientists better understand where the worm travels in its strange life.

Credit: Kat Bolstad
Another mystery squid thawed on the head and tentacles of a giant squid.

Bolstad also wanted to retrieve a tiny calcium carbonate bone called a statolith from inside the squid’s head that could hold a clue to the giant squid’s lifespan – one of the creature’s many mysteries. “The squid has this little crystal floating inside a fluid-filled chamber,” Bolstad said. “The movement of the crystals inside tells the squid about its movement, timing and position.” Squid statoliths function as our ear canals, helping the squid balance in the water. They also have growth rings, which could theoretically help estimate the squid’s age. But even if scientists can count growth rings, they still don’t know how often they accumulate, Bolstad said.

But a giant squid statolith is about a third the size of a grain of rice, making removing a larger squid quite complicated. “It’s very difficult to cut a frozen giant squid head off,” Bolstad said. “You need it to be like this sweet spot of partially thawed, but not too thawed.” The crystals always occur in a fluid-filled chamber in the same general region as the squid’s head, so scientists need to bring a scalpel to the area without crushing or breaking the fragile crystals. “It’s a bit of a lottery,” she said, adding that she had successfully caught one of the squid’s two statoliths.

Although the squid cube was perhaps the largest squid of the frozen group, Bolstad’s lab thawed another squid of significant size that turned out to be the head and arms of a really large giant squid. Although the partial specimen lacked most of its body, the head and arms alone weighed more than the small giant squid.

While Bolstad was in the lab, NIWA asked if she could identify a small specimen collected separately. The squid, which resembled a tiny burrito, was the elusive and iconic ram’s horn squidspirula spirula. The species gets its common name from a delicately coiled shell inside its body, which could be seen protruding from the mantle.

Credit: Kat Bolstad
Sheep Horn Squid, spirula spirula, looking quite real in death.

This year’s squid unboxing has unearthed at least 30 species that have yet to be described and named, Bolstad said. “It’s a chance to potentially open a box and really make a discovery,” she said. “Try taking something out of a box that one or two people have seen before,” she added.

Bolstad’s laboratory has preserved around 20 specimens to be kept in the collections of the Museum of New Zealand Te Papa Tongarewa. Your lab will return to Wellington next year or sooner to do it all over again, unwrapping bags and unpacking cubes of tiny giant squid, giant giant squid and many other squid of all sizes, watching as much as they can before they rot. settle down.

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