Spider Crab Size: How Big Do They Get, Are They Bigger Than Humans?

Spider crabs, better known as Japanese spider crabs, are among giant crabs that span up to 12.5 ft. (381 cm) from their front claw tip to the other.

These Japanese spider crabs are also the world's largest anthropoids, animals with multiple-jointed appendages, external skeletons, and have no backbone. The Japanese spider crabs are known to have ten legs.

Large and even scary-looking, this spider crab from Japan is known for its humongous body but did you know that despite its large body, these spider crabs are known to be gentle predators? Their ferocious looks can be deceiving as their behavior is known to be calm. Their calm behavior is what makes them gentle predators. Their diet includes algae, shells, and other marine animals. Both the males and females have an orange body which is quite eye-catching if you ask us!

If you enjoy reading about crabs, then do not forget to check our articles on what do crabs eat? And how many legs does a crab have as well?

What is a Japanese spider crab?

Say hello to the largest crab in the world that also looks like a spider! The spider crab, weighing up to 40 lb.(18.14kg) and can grow up to 18 ft.(5.48 m) as measured from both claws, is known to grow to triple the size of an average man! No wonder this Japanese spider crab is also one of the largest living anthropoids. When fully grown, the leg span of these spider crabs can reach up to 12 ft.(3.65 m), body size to be 15 in.(38cm) weighs up to 44 lb.(20kg). Their oval-shaped width and rounded shell reach up to 12 in.(30 cm), and the male spider crab is larger than the female spider crab.

The Japanese spider crab belongs to a group of crustaceans such as insects and spiders. It is usually found on the Japanese coast, which is also the reason it is known as a Japanese spider crab. Did you know that their massive long spider-like legs continue to grow till the crab ages? Its orange body also has white-spotted legs. Its appearance tends towards being short. Unlike the human spines, the spider crab's spines stick out between them, and their stubby eye stalks are located in front of their carapace.

What size is a Japanese spider crab baby?

Like any other animal species, females reproduce after mating with males. The reproduction process takes place after the molting of the female crab. The fertilization is internal, and the result of the reproduction process are eggs that are initially in the abdomen of the females before hatching. Post hatching, the Japanese crab baby becomes tiny transparent, round, and legless larvae. You could also find these larva drifting on the ocean like plankton.

As enormous as these spider crabs are, they start as being equally tiny. The females produce about a million eggs of size 0.03 in(0.76 mm) each. Although not all of the eggs hatch, the ones that do after ten days don't get much parental care, and they are known to molt for the first time after 9-12 days after they hatch.

Can giant Japanese spider crabs grow bigger than people?

A spider that's not a spider, but a crab can be more enormous than you can imagine! The Japanese spider crab gets its enormity from its tall and large legs, which makes them monstrously huge. They are not just a giant crab to exist but also one of the longest living animals, with their lifespan range going up to 100 years.

Despite their spindly, spider-like looks, these species are not even close to the size of spiders and are much huge. This means that these species will grow bigger than an average person, and they will also tend to become more docile. These species are even considered to be lazy to some extent.

Japanese Vs. European Spider Crab Size

Two very prominent species on the ocean surface would be Japanese spider crabs and European spider crabs.

The Japanese spider crab's habitat is mainly in the depths of the pacific ocean near Japan, and the European spider crab's habitat is in the depths of the Atlantic ocean around Africa. The Japanese spider crab inhabits the sandy bottom at depths of 164.04-328.08 yd (150-300 m), whereas the European spider crab is found at rocky depths of 21.82-98.42 yd(20-90m). European spider crab's size has an average carapace range of 7.87 in(20 cm) as measured from both its claws, whereas the Japanese spider crab has a carapace width of 15 in(38 cm).

Why are they so big?

The most common question surrounding these marine groups of species found in the Pacific is about the status of the enormous range of their size; why are they so huge? What makes them so big that they can even beat a human's size? Let's find out!

The long legs of the species enable them to grow enormously, and the reason it happens is because of their diet. The various animals fed to these species include shellfish, other dead animals, plants, mollusks, algae, and small fish. These crabs molt and shed their shells to grow new ones, making this animal as big as it is. The terrifying fact, however, is that the older these species get, the bigger they get! One of the largest crabs ever caught was only 40 years old; imagine their size when they turn 100!

Conserving Spider Crabs

Owning a crab as giant as you would be fascinating, which is why it is so essential to protect and conserve these species. Over the years, the population of these species has diminished, and so many efforts and laws are now being put in place to protect these mild predators.

One of the methods used to recover these animals is by growing artificially cultured juveniles in an aquarium. Other laws to prohibit fishermen from catching spider crabs, particularly during the months of January to April, have also been implemented.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for spider crab size, then why not take a look at different types of crabs or Spider Crab Facts?