Some like it hot (if they’re riddled with parasites)S   The bird
tapeworm Schistocephalus solidus, like many parasites, has a
complicated life cycle. As its name suggests, it infects birds,
and particularly those that live by water. It reproduces in its
host's intestines and its eggs plop into the water along with
the bird's droppings. There, they hatch into larvae that infect
small crustaceans call copepods. These are then eaten by
sticklebacks, which are, in turn, eaten by birds. Once inside
its final host again, the tapeworm can mature into an adult and
lay new eggs.  To ensure that it completes its life cycle, the
tapeworm manipulates the behaviour of its stickleback host. The
fish becomes less averse to risks, more likely to swim alone,
and less likely to flee from a predator. With such a laissez-
faire attitude, it inevitably gets eaten by a bird.  But the
tapeworm needs something else from the stickleback – time to
grow. They have to get to a weight of 50 milligrams to be sure
of successfully infecting