Some sea urchins海胆 have venomous (toxin) spines
A、sensuous(feeling)C
暂无解析
Eyespots,themostrudimentaryeyes,arefoundinprotozoan原生动物flagellates鞭毛虫,flatworms扁形虫,andsegmentedworms片段蠕虫.
Solidgeometryhasenabledastronomerstocalculatethepositionsoftheheavenlybodiesrelativetooneanother.
Insectpestsareamongtheleadingcausesofcropfailure.
ThefuturesurvivalofthebaldeagleisstillanimportantAmericanecologicalconcern.
Formulatedin1823,theMonroeDoctrineassertedthattheAmericaswerenolongeropentoEuropeancolonization.
