Common jellyfish  (Aurelia aurita)

Asexually: Of asexual reproduction: reproduction that does not involve the formation of sex cells (‘gametes'). In many species, asexual reproduction can occur by fission (or in plants ‘vegetative reproduction'); part of the organism breaks away and develops into a separate individual. Some animals, including vertebrates can develop from unfertilised eggs, this process, known as parthenogenesis gives rise to offspring that are genetically identical to the parent.
Larvae: Stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Planktonic: Aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).

1. Integrated Taxonomic Information System (ITIS) (September, 2009)
   http://www.itis.gov/
   
2. Fish, J.D. and Fish, S. (1996) A Student's Guide to the Seashore. Second Edition. Cambridge University Press, Cambridge.
   
3. Animal Diversity Web (January, 2003)
   http://animaldiversity.ummz.umich.edu/accounts/aurelia/a._aurita.html