Belonging to the crustacean family, crabs appeared on the planet over 200 million years ago during the Jurassic period.
From the giant Japanese Spider Crab to the small European Green Crab, this article takes a closer look at the most popular types of crab and their physical characteristics, making it easier to spot them in real life.
Keep reading about the different kinds of species you may encounter in the ocean or along the shoreline!
The Snow Crab, also known as the Queen Crab because of its long legs, has a spider-like shape and a hard and round shell. The exoskeleton of a Snow Crab is a dark shade of brown with a lighter shade underneath.
Male and female Snow Crabs have slightly different abdominal flaps, with the male crab having a triangular abdominal flap and the females having a rounded abdominal flap.
Snow Crabs are fond of cold weather temperatures and live in the North Atlantic and North Pacific oceans. Experts believe temperatures above 7°C can be detrimental to a Snow Crab’s survival.
King Crabs rank among the largest crab species to have existed, weighing about 11 lbs with long legs 6 ft in length. They have a fan-shaped abdomen, which visually looks like a tail.
King Crabs can’t swim and are found in the shallow coastal waters or walking near the ocean shoreline.
They are native to the Bering Sea between Alaska and Russia, with a short harvesting span of the winter season. Male King Crabs are larger than female King Crabs.
The Dungeness Crab lives in colder environments on the sandy, muddy bottom areas of the seafloor.
It is mainly found on the West Coast, anywhere between the Alaskan Aleutian Islands to Southern California.
Dungeness Crabs have a yellowish-brown to a purplish toned exoskeleton, with an oval-shaped carapace. Unlike the Snow Crab and the King Crab, these types of crab have only four walking legs.
They also have light-colored claws from the bottom and sharp teeth, and their shells grow to almost 9 inches wide.
Blue Crabs are native to the Atlantic and Gulf coasts, from Nova Scotia to the Gulf of Mexico. Blue Crabs have long shells about 9 inches across, five pairs of legs, and a set of sharp, bright blue claws in the front. The fifth pair of paddle-shaped, flattened legs render the Blue Crab a strong swimmer.
Their exoskeleton is blue-green. One way to differentiate between a male and a female Blue Crab is by observing the claws since the females have red tips on their claws, whereas the males have bright blue claws.
While they are not generally a threat to humans, Blue Crabs have an aggressive nature and are most likely to bite when threatened.
The Florida Stone Crab is most commonly found in bays, seagrass beds, and oyster reefs of the Western North Atlantic.
Florida Stone Crabs have a brownish-black, oval shell that stretches up to 5 inches in females and 5.7 inches in males.
These types of crab have an exoskeleton and five hair-covered legs, which are red and yellow. Adult stone crabs have a trunk of 14 segments. Young stone crabs have a deep purple-blue color.
The female crabs have larger shells, whereas their male counterparts have bigger claws. The brownish-black carapace blends easily with any muddy surface, providing them protection from predators.
The Peekytoe Crab, also known as the Rock or Sand Crab, is yellowish-orange on top and white underneath.
The Peekytoe Crab inhabits rocky environments on the East Coast of North America. It can grow up to 5 inches across and has a red or orange shell.
The crab has a fan-shaped shell with a rounded front. There are two antennas between the front part of their shell that help with taste and smell.
It also has two flexible eyestalks with three spines located on top of it, and the rest of the nine spines sit on the borders of the shell.
The Peekytoe Crab has large deep brown claws with light tips. That is one of its most distinctive features.
Similar to the Hermit Crab, the Horsehair Crab is comparatively smaller than most other crabs. Its carapace length ranges from 4-5 inches and can weigh as much as 2.2 lbs.
The Horsehair features a hard shell and soft and pointy tiny hair over its body, a characteristic from which it derives its name. These offer the Horsehair Crab protection from predators.
Brownish or muddy gray, Horsehair Crabs are mainly found in the shallow depths of Japan’s Hokkaido coast and some areas around the northwest Pacific Ocean.
Just as the name suggests, the Japanese Spider Crab inhabits the waters of Japan and resembles a spider.
It has a round body with long legs, with the male Japanese Spider Crab growing larger than the female crab.
This crab is hard to miss due to its size. It can grow up to 12 ft from claw to claw and weigh as much as 40 lbs.
The Japanese Spider Crab has a pear-shaped shell that becomes leaner as it reaches the head. Its color is orange to light brown.
Even though it has long legs, the legs are often weak, and it is common to see these crabs missing at least one limb.
The European Crab is also known as the European Green Crab. It is green on the outside and contains yellow or red patches underneath.
It has an indented, pentagon-shaped shell. As the shell approaches the face, there are five sharp spines on each side of the eye.
The hind legs are hairy, pointy, and flat, and the claws in the front are different sizes. The Southern European Crab is prone to biting when it feels threatened, as it is aggressive by nature.
The Brown Crab, or Cancer Pagurus, is a species of crab most commonly found on the coastline of Norway and inhabiting the depths of the North Sea, North Atlantic Ocean, and perhaps the Mediterranean Sea.
Brown Crabs typically have a carapace length of 2 inches and a width of about 6 inches. However, they can reach up to 6 inches long and almost 10 inches wide, respectively, in some exceptional cases.
This large crab has an oval-shaped shell, with distinctive edges resembling a pie crust. It is brown with white patches and black, large claw tips. Like most other crabs, Brown Crabs have teeth inside their stomach, helping them digest food.
Hermit Crabs are small crustaceans that are very different from other crabs because their exoskeleton is only present on the front part of their bodies, and they have a curled tail at the backside of their body.
Since the Hermit Crab has around 800 species, it is difficult to pinpoint its exact physical characteristics, especially its color, because they vary from species to species. Hermit Crabs can grow around 6 inches long and live on land near the shoreline.
One thing common in all Hermit Crab species is that they continually outgrow their shells as they grow.
Consequently, they look for abandoned shells that are large enough to borrow for their new growth as part of the molting process.
Horseshoe Crabs have a hard exoskeleton with an arc-shaped, hard, brownish-green shell. The crab gets its name from its arc-shaped shell, which resembles the shape of a horse’s shoe.
The Horseshoe Crab is born with ten legs, and near the legs are the feeding pincers and the mouth. Below the mouth is the abdomen, which also contains gills that help the Horseshoe Crab breathe.
Horseshoe Crabs seldom come on the shore, except during the spring season when they mate. More often than not, they live deep inside the ocean water.
The spines and spikes on the Horseshoe might make them look intimidating; however, they are harmless species.
Out of all the different types of crabs discussed here, these are the only ones that aren’t actual crabs but chelicerates.
The Coconut Crab is a large size nocturnal land crab found in the Pacific and Indian Oceans and the largest arthropod in the world.
It can grow as long as 3 inches, almost 8 inches wide, weigh up to 9 lbs, and is the largest species of land crab in the world.
Although it is generally blue, its colors vary significantly from light and dark blue to even red or black.
With that said, the Coconut Crab generally keeps its distance from humans and is afraid to come near or attack them unless threatened.
As the name suggests, the Coconut Crab’s favorite and primary source food is coconuts which occur in abundance on islands in the Pacific and Indian Oceans.
The Jonah Crab inhabits the deep waters of the North Atlantic Ocean from Newfoundland to Florida. Like the Dungeness Crab, it has an oval shape but slightly larger claws and a darker, rough texture.
It features a reddish shell and is yellow from underneath. Jonah Crabs can grow as wide as almost 9 inches, with male crabs growing larger than their female counterparts.
Despite having powerful claws, the Jonah Crab is not a very aggressive crab species. However, with that said, there is not much known about the Jonah Crab’s life cycle or behavior due to the lack of research studies on the species.
The European Green Crab is a globally widespread invasive species of crab first discovered in San Francisco Bay in 1989.
It now exists in abundance in the waters of North America, South America, Australia, and Asia. Although its color is dark green, the colors can vary as they molt. Adult European Green Cabs can sport various colors, including red and yellow.
The most distinguishing feature or identifiable characteristic of this medium-sized crab is its five-pointed spines, or teeth, found outside the eye on its shell.
It also features three small knobs between its eyes, which is unique to this particular species. Its shell is triangular, and the European Green Crab averages 2 – 2.4 inches in width but could reach up to 3.5 inches in some rare cases.
The European Green Crab is a voracious predator that feeds on various organisms like shellfish and other crabs, posing a significant threat to environmental resources and local ecosystems.
Also known as Tanner Crabs, the Bairdi Crab is one of two species of Snow Crabs, along with the Opilio Crab found in the Bering Sea. Larger than the Opilio Crab, it features five pairs of legs with pincer claws on its first pair of legs.
The Bairdi Crab is brown with a rough, bumpy texture. It has a short tail and can reach sizes up to 5 lbs, with a carapace width of about 1 inch. It mainly feeds upon clams, worms, and other ocean bottom crustaceans.
There are many more crabs to encounter on the beach than the common King or Hermit Crabs.
Crabs are widespread, and there are about 7000 species worldwide, with most of them belonging to the Brachyura family.
As is evident, each species has unique characteristics that help separate it from other crabs. We hope this article serves as a helpful resource to help you distinguish between the different types of crab species.