Boreopacific armhook squid facts for kids
Quick facts for kids Boreopacific armhook squid |
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| Gonatopsis borealis museum specimen from National Chung Hsing University, Department of Life Science | |
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The Gonatopsis borealis, also known as the Boreopacific armhook squid, is a fascinating type of squid. You can find it living in the cool waters of the North Pacific Ocean. It belongs to a group of squids called the family Gonatidae. This squid is very common in its habitat.
Even though it's often caught by accident by fishing boats, it's super important for the ocean's food chain. Many other animals, like fish and marine mammals, rely on it as a main food source.
What Does It Look Like?
The Gonatopsis borealis is a medium-sized squid. Scientists have noticed there are three different types based on their body size: large, slender, and small. They are still studying if these are different species or just variations.
This squid has some special features. Its arms are quite short and have blunt tips. Near the tips, the arms have four rows of suckers. Its body, called the mantle, is very muscular. The arms are about 40-45% as long as the mantle. Some arms are longer than others.
Young squids develop hooks on their arms as they grow. This happens when they reach a mantle length of about 35 to 45 millimeters. Unlike some other squids, the male Gonatopsis borealis does not have a special arm called a hectocotylus for mating. Interestingly, these squids lose their tentacles when they are still very young, at the paralarva stage.
They have big eyes and a special ridge on their neck called a nuchal crest. The muscular mantle is shaped like a cylinder and gets narrower towards the back. Their fins are short and wide, shaped like a diamond. This squid does not have a tail. Its skin is usually a dark reddish or purplish-brown color. It also doesn't have any photophores, which are light-producing organs.
Adult males can grow up to 270 millimeters (about 10.6 inches) in mantle length. Females can get even bigger, reaching up to 330 millimeters (about 13 inches).
When they are very young, called paralarvae, you can tell them apart by the pattern of their chromatophores (color-changing cells) on their head. They have three rows of these cells on their back.
Where Do They Live?
The Gonatopsis borealis lives across a huge area of the North Pacific Ocean. Its home stretches from northern Japan, through the Okhotsk Sea and Bering Sea. It also lives all along the Aleutian Islands and into the Gulf of Alaska. From there, its range goes south along the western coast of North America, reaching as far as California and even Baja California.
The very first specimen of this squid that scientists studied was found off the coast of Hokkaido, Japan.
Life in the Ocean
This squid is an oceanic species, meaning it lives in the open ocean. It's one of the most common and widespread squids in its family. You can find it in cold waters, from the surface all the way down to very deep parts of the ocean, sometimes as deep as 1500 meters (about 4,900 feet).
These squids perform a daily journey up and down the water column. At night, they swim closer to the surface. They often gather in huge groups, especially from spring to early autumn. In some areas, like the Okhotsk Sea, they can make up to 68% of all squid catches during summer. This shows just how many of them there are!
While they can be found at various depths, they are most common in the middle layers of the ocean, usually between 300 to 500 meters deep. During the day, smaller squids tend to stay deeper to avoid larger, cannibalistic adults. At night, they move up to shallower waters to feed.
Gonatopsis borealis squids eat a variety of things. Their diet includes small ocean creatures like euphausiids (krill), hyperiid amphipods, and copepods. They also eat fish and even other squids. These squids typically live for at least one year.
Many animals prey on Gonatopsis borealis. These include different types of fish like salmonids, walleye Pollock, and albacore. Larger squids, like Berryteuthis magister, also hunt them. Even other Gonatopsis borealis squids can be cannibals! Other predators include seabirds, seals, sea lions, dolphins, and large toothed whales like sperm whales and pilot whales.
Squid Fishing
The Gonatopsis borealis is a very abundant species. In the Sea of Okhotsk, for example, there could be as much as 278,000 to 500,000 tonnes of this squid during the summer. Huge numbers are also found in the Bering Sea and near the Kuril Islands.
Most of the squids caught are the larger body type. They are often caught by accident (as bycatch) when fishing boats are trying to catch other fish or squids, like salmon or the neon flying squid. They are caught using jigs or in large drift gillnets.
People say that the meat of this squid tastes very good. Because there are so many of them, some think it could be a good target for future fisheries. However, this squid plays a very important role in the ocean's food web. It's a key food source for many valuable fish species. Because of this, its ecological role might be more important than developing a specific fishery just for this squid.
About Its Name
The Gonatopsis borealis is a bit different from other squids in the Gonatopsis group. It has seven rows of teeth on its radula (a ribbon-like tongue with teeth), while others usually have five. Because of this, one scientist, Kir Nesis, suggested it should be in its own special group called a subgenus, named Boreoteuthis. Some experts even think it should be a completely separate genus. Scientists are still working to figure out the exact classification of this squid and its different size types.
In the Asian part of its range, there are two distinct groups of Gonatopsis borealis. A northern group matures at a smaller size (less than 180mm mantle length). A southern group, found further south, matures at a larger size (over 220mm mantle length). These two groups can sometimes be found living in the same areas, like off the Kuril Islands.
