Have you ever heard about animals evolving from others? Yes, you probably have. Humans evolved from chimps. But have you heard of lobsters evolving into crabs? Probably not.
In this post, you will discover species of "crab" that used to be a lobster.
Meet the Flat Porcelain Crab. If you live in Coastal California, you are probably within ten miles of one. These tiny crabs live under rocks or in mussel beds in California. They use their antenna to sense food and their feathery mouthparts to filter out plankton. But did you know this crab isn't a true crab?
This "crab" used to be a lobster. Through a process called Carcinization, this specific species built a crab-like body throughout time. It's abdomen is concealed underneath it's body. It's got even sized pincers and walks sideways. But why did this specific species decide to take the crab path. Well, there are many theories why. The most interesting one relates to Natural Selection. Thousands of years ago, a relative of a crustacean probably decided to live near rocks, where today's crabs are found. Because of that, it developed a flat body and the ability to walk sideways. That way, it could slip easily under rocks.
Over the years, that bug's offspring would gain more desired traits, such as an abdomen concealed under the body. Later, you would get the Flat Porcelain Crab (Petrolisthes cinitipes). Although it might look like a crab, it isn't one.
Above is the evolution of crabs. As you can see, there are lots of crab body types, evolving from one type of alien looking water bug.
Look at the top right corner. Look two spaces down. That's a porcelain crab. Now look diagonal-left from it. That "crab" with a squishy abdomen and one giant claw is a hermit crab. Hermit crabs are not crabs, or lobsters. They are simply just crustaceans.
Look at the bottom row. The brown, shiny one is a coconut crabs. These "crabs" are closely related to hermit crabs, except ten times bigger! They are false crabs as well.
Throughout the image, there are also mole crabs (Emerita spp. and Blepharipoda occidentalis.) Mole crabs are not related to crabs OR lobsters. However, they might of developed from a Hawaiian species, the Kona Crab.
That is a Spiny Mole Crab (Blepharipoda occidentalis).
That is a Kona Crab (Ranina ranina)
As you can see, these crabs share similar aspects, such as swimming backwards, having pincers, having long protruding eyes and burying into the sand. But the mole crab isn't a true crab!
Later, the spiny mole crab probably evolved into the Pacific Mole Crab, the well-known egg shapped digger.
That's it for today!
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