Lobster vs Crab
Both lobster and crab are crustaceans, which is a main group among arthropods. They share many features between them including the calcified carapace, but the exhibited differences between crabs and lobsters are important to know. Difference in the taxonomical diversity would be important to know about the adaptabilities of these two types of crustaceans. Additionally, there are many other aspects to portray the difference between them.
Lobster
Lobsters are marine crustaceans with large bodies, but they are sometimes found in brackish waters, as well. Lobsters are classified under the Family: Nephropidae of Order: Decapoda and Class: Malacostraca. There are many types of them known as clawed lobsters, spiny lobsters, and slipper lobsters. They all sum up to make 48 extant species described under 12 genera. As the name of the included taxonomic order indicates, Decapoda, each lobster has 10 walking legs with the first one being clawed. They have a good efficient sensory system with antennae and antennules, which is important especially for those living in brackish water. Lobsters have a very hard exoskeleton made of chitin. Their body size could be as high as 50 centimetres long, which is a very large size for an invertebrate.
Lobsters have a worldwide distribution, living in all the seas except in the polar waters. They mostly prefer to live in the continental shelf including rocky, muddy, or sandy bottoms. Their hard and calcified exoskeleton is shed when they are ready to grow their body size, and this happens three to four times a year until they are about six years old and after that they shed only once a year. This shed exoskeleton is a good source of calcium for them to harden their skin, and they eat it after shedding. However, they are mainly omnivorous in feeding habits and eat both phytoplankton and zooplankton. Therefore, the taste of lobsters differ depending on their food habits, when they are cooked. It is a very highly priced food both as a raw meat as well as a cooked food.
Crab
Crabs are crustaceans with ten legs or with five pairs of legs so that they have been classified in the Order: Decapoda. There are more than 6,700 species of crabs in the world, out of which the vast majority is found in the sea, and only about 850 species live in the freshwater or terrestrial environments. Although it was believed that the modern crabs have been originated from a single precursor, the evolutionary evidences suggest two lineages from distinct ancestors to have new world and old world types. However, the main feature of crabs is their large carapace that covers them, but the tail is hidden ventrally underneath the body. This large carapace is made up of calcium, and it provides a great deal of protection for the crab in many ways such as being an exoskeleton and a surface for muscle attachment. Sexual dimorphism is prominent in crabs, though it is not readily seen to the exterior, which is because their tails (abdomens) exhibit the main difference between males and females. Abdomen is broad and round in females, whereas males have a narrow and triangular shaped abdomen. The most interesting behaviour of crabs is that they move sideways but not forward and backward. However, there are few species with the capability to walk forward and backward, as well. Crabs are well known as a delicious food around the world, which means they are a great protein source for the humankind.
Lobster vs Crab
• Crabs are highly diversified than the lobsters are.
• Lobsters live in the ocean, whereas crabs are found in seawater, freshwater, and semi-aquatic conditions.
• Body size is larger in lobsters than in crabs.
• The meat of crabs, especially the meat of legs, is more popular than lobster meat.
• Crabs usually walk sideways, while lobsters move forwards and backwards.