They have hard shells
They have the longest front chelicerae of any crab
They have the name of resembling spiders
The crustacean subphylum Crustacea (Crustacea) Decapoda, Spider Crab family (Majidae or Maiidae) of invertebrates Collectively. The body is thicker and rounded, with long, slender legs and slow movement. Most eat carrion. Widely distributed, seafood, in warm water for economic fisheries, such as the North Pacific and other places. Some are very small, such as the long-beaked large-footed crab (Macropodia rostrata) off the coast of Europe, which is about 1 centimeter (less than 0.5 inches) in diameter. The largest spider crab is the giant crab (giant crab; scientific name Macrocheira kaempferi) in the Pacific Ocean near Japan, whose two chelae, when extended, are more than 4 meters (13 feet) apart, and is probably the largest arthropod. The head is often beak-shaped, and the body is usually covered with hairs, spines, or tubercles, as well as growths of seaweed, sponges, or other organisms. A mucus-like secretion from the crab's mouth sticks these substances to the body. Rock crabs (Pugettia producta) in seaweed along the Pacific coast from Canada to Mexico are about 1.25 centimeters (0.5 inches) wide and 2.5 centimeters (1 inch) long; green and red on the back and green underneath. The diamond crab (Parthenope investigatoris) in the Indian Ocean camouflages like the surrounding coral. The Maja squinado of the Mediterranean and southwestern European coasts is up to 18 centimeters (7 inches) long. spider crabs of the genera Libinia, Hyas, Sternorhynchus, Pitho, and Lambrus are common along the Atlantic coast of North America. Spider crabs of the genus Libinia on the Pacific coast belong to the genera Loxorhynchus, Pugettia, and Epialtus.
Peculiar Appearance
Looking at the long limb trunks and small carapace it's easy to see how the spider crab got its name. Spiny dorsal armor, sharp gangly legs, and long walking feet. This spiny spider crab is the largest crab in Europe, with nearly 100 different species off the coast of Australia, and is easy to catch because of its sluggishness, despite its long chelicerae.
Biggest spider crab
The biggest spider crabs are the Japanese spiny crabs, which are also the largest of the crustaceans. They have long claws that extend to a full length of 3.7 meters, and their breastplate is 64 centimeters wide. Fishermen in Japan claim to have seen these crabs as wide as 98 meters (that's an exaggeration, isn't it?). Found in Japan's North Pacific Ocean, the fearsome-looking spiny crabs are caught for food, no doubt enough to feed a large family. But museum scientist Chad Goeden, in his In his "Japan Diary," museum curator Chad Gordon shows a photo of him wearing the breastplate of a dead spike crab on his head and holding two of the crab's giant claws, which are taller than he is.
Killer crabs (large spider crabs that actively attack humans) have also recently appeared in Japan
The photo on the right shows 50,000 spider crabs taking part in a mating extravaganza at a depth of 4 meters in Philips Harbour Bay, Melbourne, Australia.