Jellyfish Rule! --- Moon Jellyfish [LiveScience 2011-04-28] The
moon jellyfish is believed to have been introduced into many new
environments by ships, when the jellyfish's stationary
developmental stage, called a polyp, attached to their hulls or
came in via the ballast water, which ships dump once they arrive
at their destination. Jellyfish are simple, successful and,
occasionally, deadly creatures. The Australian box jellyfish has
enough toxin in each of its tentacles to kill 60 people. Some
jellyfish create spectacular blooms when fields of polyps, their
stationary life stage, simultaneously bud off into free-floating
medusae. These blooms are blamed for the deaths of swimmers,
clogged fishing nets and power plant intakes, and in certain
parts of the world, like Japan, they appear to be on the rise.
But these problems are associated with only a subset of the
creatures we call "jellyfish" – a catch all term for an
amazingly diverse group of organisms. It includes corals, true
jellies and others with stingi