The Invertebrata

abdomen adult alimentary canal animal antennae anus appear appendages attached base bears become Biol blood body branches buds cavity cells ciliated Class closely coelom colony common complete consists contains cytoplasm digestive direction divided division dorsal duct ectoderm eggs external eyes feeding female four function ganglia ganglion genital gills gland gonads groove head host important individuals insects internal Jour known larva lateral layer legs limbs living longitudinal male mantle mouth movements muscle nerve nervous system occur opening Order organs origin pair parasitic passes plates polyp possess posterior present primitive proboscis produced Protozoa pupa region reproduction resemble rest secretion seen segments separate shell short side single sometimes somites species stage structure Suborder surface takes tentacles thoracic tissues trunk tube Turbellaria usually various ventral vessel wall whole wings