What’s inside the Squid Cube?

What’s inside the Squid Cube?

In a containment lab in Wellington, New Zealand, Kat Bolstad examined the squid cube. It was the size of a barrel and had been frozen since January, when it was brought up during a research trawl in fishing grounds in the east of the country. The squid cube was not a squid cube but rather a single cube-shaped squid, the flaccid body of which had been folded into a rectangular fish pan and then stored in a freezer. It chilled there until June, when Bolstad, a deep-sea squid biologist at Auckland University of Technology, was ready to unbox it.

“This isn’t the first squid cube,” said Bolstad, who has seen many cubes of different sizes and species in his work. But it was definitely a very special squid cube, comprising the carefully pleated body of a whole giant squid, that is, a species of deep-sea squid in the family Architeuthidae. When giant giant squids are caught in research trawls, their bodies are too large to be cubed, i.e. stored whole in a standard 50 liter fish tank. These true giants are often frozen in pieces or “whole, in a kind of gigantic, very big, sausage-shaped package that has to be moved by a forklift,” Bolstad said. But this giant squid, a young female, was just small enough to fit in the fish tank and become a full-fledged cube. As Bolstad described the squid’s body arrangement: “It was like a cat curled up for a nap inside the fish tank.”

About twice a year Bolstad’s lab visits Wellington to thaw cubes of squid and other squid (frozen squid that look a little less like regular geometric shapes). The city is home to the marine collection facilities of the National Institute for Water 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 regains heat. And the quality of the carcasses can vary a lot depending on the course of the squid from the bottom to the surface. “Sometimes you get a really nice one,” Bolstad said. “Sometimes it looks like someone sneezed into a tray.”

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

Successfully unpacking frozen squid can be a race against time: Bolstad’s lab and NIWA staff members must finish their job before the flesh begins to rot. Although a single finger-sized squid can thaw in half an hour, larger squids can take an entire day. And a squid packed into a cube also doesn’t thaw evenly, which risks rotting the outside of the cube while the inside is still frozen. A few years ago, Bolstad had to thaw a squid cube from a colossal squid – a completely different species and the largest invertebrate on the planet – weighing over a thousand pounds. Colossal squid tissue is more delicate than giant squid tissue, so Bolstad’s team thawed this colossal cube in a bath of sea ice to keep the dead squid in a relatively pristine state.

June’s squid cube was less difficult, thawing in the air overnight until researchers returned to unfold the half-thawed cube and run water over its body to help. “We had visions of it, like unfolding and then sliding across the floor and just having a horrible disaster in the morning,” Bolstad said. But the squid cube cooperated and the next day it was able to be fully unrolled and restored to its sprawling 21-foot-long glory.

The once cube-shaped giant squid, fully unpacked.

Scientists don’t often get the chance to examine giant squids. The animals are very large and live in waters thousands of feet deep, making it quite unpredictable when one might show up. For a long time, scientists could only study Architeuthis of squid that have been discovered dead on shore, dead in the water, or that have been digested or regurgitated by sperm whales, according to a 2013 article in the American Malacological Bulletin. Recent advances in deep-sea trawling and underwater camera systems have given scientists a bit more access to the elusive giants.

Still, it’s rare to come across a giant squid that hasn’t reached its full size yet, Bolstad said. Scientists are still studying the life cycle of giant squid, a cephalopod whose early childhood is somewhat like a black box. “There is a size below which specimens are basically unknown,” Bolstad said, adding that there are records of “fairly small” mature males. But female giant squids get much bigger: while a mature male can reach around 32 feet, a mature female can reach 42 feet. Mature male jumbo squids produce sperm packets called spermatophores and implant them into the skin of a female jumbo squid. But the researchers found only tiny evidence of eggs in this particular cubed squid, meaning it was an immature female that hadn’t mated.

Curious to know what it ate, Bolstad’s team gently slid the innards out of the gallon-sized squid. This week, the researchers plan to thaw the squid’s guts — which unfortunately aren’t cube-shaped but roughly oblong — and examine what half-digested creatures and undigested microplastics might be hiding inside. With any luck, they’ll find some parasites. Many parasites in the ocean have to move through different unique hosts throughout their life cycle: after being expelled by a fish, they may have to enter a snail, then perhaps a clam 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 weird little life.

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

Bolstad also wanted to retrieve a tiny calcium carbonate bone called a statolith from the squid’s head that may 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 in there informs the squid of its movement, momentum, and position.” Squid Statoliths work like 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 don’t yet know how often they accumulate, Bolstad said.

But a giant squid statolith is about a third the size of a grain of rice, which makes removing a larger squid rather tricky. “It’s very difficult to cut off a frozen giant squid head,” Bolstad said. “You need it to be like that partially thawed but not too thawed sweet spot.” The crystals always occur in a fluid-filled chamber in the same general region of the squid’s head, so scientists must 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 managed to remove one of the two statoliths from the squid.

Although the squid cube may be the largest squid in the frozen group, Bolstad’s lab thawed another squid of significant size which turned out to be the head and arms of a very large giant squid. Although the partial specimen was missing 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 tiny specimen that had been collected separately. The squid, which looked like a tiny little burrito, was the elusive and iconic rams horn squidspirula spirula. The species gets its common name from a delicately whorled shell inside its body, which could be seen sticking out of the mantle.

Credit: Kat Bolstad
rams horn squid, spirula spirula, looking quite majestic in death.

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

The Bolstad laboratory has preserved about 20 specimens which will be kept in the collections of the Museum of New Zealand Te Papa Tongarewa. His lab will return to Wellington next year or even sooner to do it all over again, unboxing bags and unboxing cubes of small giant squids, giant giant squids and many other squids of all sizes, observing everything they can before that rot does not set in.

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