Hydras, planaria and brine shrimp aren't everyone's idea of pets, but this care and feeding catalogue addresses itself to-science-minded observers and experimenters. For each suggested pet (others include toads, crickets, hermit crabs and starfish) Simon gives basic directions for creating a suitable glass-jar habitat. As always, there's a lot more that could be said about each species and anyone with a halfway serious interest could easily go beyond the brief list of suggested further reading. But Simon's condemnation of indiscriminate, careless collecting and his attempt to steer youngsters toward interesting, but non-endangered wild life is a step in the right direction.