Five completely separate groups of crustaceans independently evolved into what we commonly refer to as “crabs.” This phenomenon is called “carcinization.”

Evolution of crabs – history and deconstruction of a prime example of convergence

Compared with the elongate bodies of shrimps or lobsters, crabs are characterised by a compact body organisation with a depressed, short carapace and a ventrally folded pleon. The evolutionary transformation from a lobster-like crustacean towards a crab is called ‘carcinization’ and has been interpreted as a dramatic morphological change. Nevertheless, the crab-shape evolved convergently in a number of lineages within Decapoda. Accordingly, numerous hypotheses about internal and external factors have been presented, which all try to explain these frequent convergent carcinization events despite the seemingly fundamental changes in the body organisation. However, what a crab is lies greatly in the eye of the beholder and most of the hypothes… Continue Reading (2 minute read)

8 thoughts on “Five completely separate groups of crustaceans independently evolved into what we commonly refer to as “crabs.” This phenomenon is called “carcinization.””

  1. Getseriass

    Crab is optimal. Our destiny is crab.

  2. PonchoHung

    Infraorder: Brachyura

    * Group: True crabs

    Infraorder: Anomura

    * Group: King crabs
    * Group: Porcelain crabs
    * Group: Hairy stone crabs
    * Group: Hermit crabs

  3. Beanmanwithabigpenis

    This gives me faith that somewhere in our universe lies a water-world with an intelligent crab species.

    Where young crabs fall in crab love and learn to grow and try new crab experiences. Unfortunately some of those experiences will result in unplanned crab pregnancies and fights between the two crab families. The young crabs made a mistake, they got too adventurous but what they’re really upset about is their families seemingly uncaring attitude towards the wishes to these young crabs. There will be talk of getting a crab abortion or perhaps a crab marriage. But the young crabs want only to have this choice be their own.
    Inevitably the young, strong-willed and prideful crab mother-to-be will become a single crab mother to her little crab daughter.
    But they are strong crabs capable of facing the daunting crab world together as crab mother and crab daughter.

    As a young adult the crab daughter will not make the same mistakes her mother made largely because her crab childhood was better than her crab mother’s despite only having one crab parent. She goes to a private crab school paid for by her crab grandparents.
    This is only allowed by the crab mother because the school is good and the cost would otherwise be prohibitive. The crab mother manages a crab Inn located in a small quaint crab town with small town crab charm. But time and time again the crab that impregnated the crab mother will come around hoping that maybe things will work out between them.
    But the crab father should take the hint and stop coming around because so help me god I will kill Christopher for separating Lorelai and Luke I know it’s not entirely his fault but holy fuck I’m mad that I didn’t get to see more of Lorelai and Luke together and all I hope for is that maybe I get to see a version of Gilmore girls from a crab planet where Christopher gets eaten by a sea turtle.

  4. Villain_of_Brandon

    Just throwing this out there on the phenomenon.

  5. nsstrickland

    I’m more fond of “Crabification”, but someone clearly beat me to it.

  6. Nathaniel820

    To anyone confused, 5 different species didn’t merge together into ONE group, they just evolved into extremely similar things that we consider crabs as a whole (1 group of true crabs, 4 groups of technically not crabs but still crabs).

  7. jmmccabe84

    Crab people. Crab people. Walk like crab…

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