EntityQ1093125· pop 12· linked from 245 articlescirrusSign in to savelong, thin structures in both vertebrate and invertebrate animalsConnectionsherpetologyEntitymammalEntityCnidariaEntityglossary of plant morphologyEntityAnimaliaEntityCharles DarwinEntityheartEntitybloodEntityelephantEntityCarl LinnaeusEntityfruitEntityanatomyEntityAmphibiaEntityzoologyEntityInternational Standard Book NumberEntityVertebrataEntitymuscleEntityChordataEntitypenisEntityMolluscaEntityCategoriesAnimal anatomyAnnelid anatomy