Chionoecetes opilio facts for kids
Quick facts for kids Chionoecetes opilio |
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| Snow crab | |
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Oregoniidae
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C. opilio
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| Chionoecetes opilio (O. Fabricius, 1788)
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The Chionoecetes opilio, also known as the snow crab or opilio crab, is a type of crustacean. It mostly lives on the ocean floor in the northwest Atlantic Ocean and north Pacific Ocean. This crab is a well-known species that people catch for food.
There are seven species in the Chionoecetes group, and they are all called "snow crab." C. opilio is related to other crabs found in cold, northern oceans.
Contents
What Does a Snow Crab Look Like?
Snow crabs have a hard, protective shell called a carapace that covers their bodies. This shell is about as long as it is wide. They have small bumps, or tubercles, on their shells.
At the front of their shell, they have a horizontal extension called a rostrum. It has two flat horns with a gap between them. Snow crabs also have tiny bumps along the edges of their bodies.
Their walking legs are somewhat flat. Their pincers, called chelipeds, are usually smaller than or the same size as their walking legs. Snow crabs can be brown to light red on top. Their undersides are yellow to white, and the sides of their feet are bright white.
Where Do Snow Crabs Live?
Snow crabs live in the Northwest Atlantic and North Pacific oceans. In the Atlantic, you can find them near Greenland, Newfoundland, in the Gulf of Saint Lawrence, and on the Scotian Shelf.
In the Pacific, they live from Alaska to northern Siberia. They are also found through the Bering Strait to the Aleutian Islands, Japan, and Korea.
Snow Crabs in the Barents Sea
In 1996, snow crabs were seen in the Barents Sea for the first time. Scientists believe they are an invasive species there. This means they are not naturally from that area and could harm the local animals. It is not clear how they got there.
Another crab, the red king crab, was brought to the Barents Sea on purpose and has settled there. Snow crabs might also cause problems for the animals that naturally live in the Barents Sea.
Their Ocean Home
Snow crabs live on the ocean's shelf and upper slope. They prefer sandy and muddy bottoms. You can find them at depths from 13 to 2,187 meters (about 43 to 7,175 feet). On average, they live at about 110 meters (360 feet) deep.
In Atlantic waters, most snow crabs are found between 70 and 280 meters (230-920 feet) deep. Male and female crabs might live at different depths. Smaller adult males often stay at middle depths. Larger, stronger adult males are usually found deeper than 80 meters (260 feet).
Adult females like to gather together at depths of 60 to 120 meters (200-390 feet). Snow crabs prefer very cold water, usually between -1 and 5 degrees Celsius (30-41 degrees Fahrenheit). They can live in water up to 10 degrees Celsius (50 degrees Fahrenheit).
What Do Snow Crabs Eat?
C. opilio crabs eat other small ocean animals. These include other crustaceans, bivalves (like clams), brittle stars, and polychaetes (a type of worm). They also eat tiny plants and single-celled organisms.
Snow crabs are also scavengers. This means they eat dead plants and animals found on the ocean floor. They also hunt worms and mollusks.
Male crabs are usually better hunters than mature females. What they eat depends on their size. The smallest crabs mostly eat tiny shrimp-like animals and brittle stars. The largest crabs mainly eat worms, other crabs, and fish. Sometimes, snow crabs even eat each other, especially medium-sized females.
How Big Do Snow Crabs Get?
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Snow crabs grow slowly. Male crabs are usually almost twice the size of female crabs. Males can grow up to 16.5 cm (6.5 inches) wide across their shell. Females can grow up to 9.5 cm (3.7 inches) wide.
The shell of a male crab is usually about 7 cm (2.8 inches) wide and long. A female's shell is usually about 5.5 cm (2.2 inches) wide and long. Males caught for food generally weigh between 0.5 and 1.35 kg (1.1-3 pounds). Females usually weigh about 0.5 kg (1.1 pounds).
Two types of tiny shrimp-like animals, Ischyrocerus commensalis and Gammaropsis inaequistylis, have been found living on the shells of snow crabs off the coast of Newfoundland.
How Do Snow Crabs Reproduce?
Snow crabs can have many babies. Each year, every female carries eggs. Females are fertilized inside their bodies. They can carry up to 150,000 eggs under their bellies after mating.
Females usually lay their eggs in very deep parts of the ocean. These areas often have a lot of dead plant material from the surface. Male crabs can mate when they are both young and fully grown.
Adult snow crabs usually live for 5 to 6 years. Before they die, they usually molt (shed their old shell), mate one last time, and then pass away.
New snow crab babies hatch in late spring, around the time tiny ocean plants called phytoplankton bloom. This means there is plenty of food for them when they are born. When they hatch, they are in a stage called zoeal. This means they are developing into larvae that can swim. Then, they change into the megalopa stage and settle on the ocean floor.
Why Are Snow Crabs Important to People?
Snow crabs are important for fishing. Many were caught in the 1980s, especially in Canada, for commercial use. Fishing for snow crabs in the Barents Sea (where they are an invasive species) started in 2013. It is expected that the number of crabs there will grow to be similar to those in eastern Canada.
Since 2016, there has been a discussion about who has the right to fish for snow crabs in the Barents Sea. Some believe the crab can be caught freely in international waters. Others argue that because the crab lives on the ocean floor and does not move much, it falls under the rules of the country that controls that part of the ocean floor.
How Snow Crabs Got Their Name
The snow crab was first described by a scientist named Otto Fabricius in 1780. He first called it Cancer phalangium, but that name was already used for another crab. So, in 1788, he gave it a new, valid scientific name: Cancer opilio. The first place where this crab was found and studied was Greenland.
Later, in 1838, another scientist, Henrik Nikolai Krøyer, created a new group, or genus, called Chionoecetes. The C. opilio was the first and only species put into this new group, so it became the main example for the Chionoecetes genus.
In 1924, Mary J. Rathbun described a type of snow crab she called C. o. elongatus. Today, scientists usually consider this to be a separate species, called Chionoecetes elongatus.
Gallery
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Steamed snow crab
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Steamed snow crab legs
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Snow crab fried rice on crab shell
See also
In Spanish: Chionoecetes opilio para niños
