Most deceptive of all—indeed probably holding the record for animals not looking remotely like the thing that zoologists know them to be—are the parasitic barnacles, such as Sacculina. Sacculina is not what it seems with a vengeance. Zoologists would never have realised that it is in fact a barnacle, but for its larva. The adult is a soft sac that clings to the underside of a crab and sends long, branching, plant-like roots inside to absorb nourishment from the crab’s tissues. The parasite not only doesn’t look like a barnacle, it doesn’t look like a crustacean of any kind. It has completely
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