Some of the lateral vessels are contractile and serve as hearts, i.e., pumping organs for driving the blood. Some aquatic annelids have thin-walled, feathery gills through which gases are exchanged between the blood and the environment. However, most annelids have no special organs for gas exchange, and respiration occurs directly through the body wall. Sense organs of annelids generally include eyes, taste buds, tactile tentacles, and organs of equilibrium called statocysts. Reproduction Reproduction is sexual or asexual.
Asexual reproduction is by fragmentation, budding, or fission.
Among sexually reproducing annelids hermaphrodites are common, but most species have separate sexes. Fertilized eggs of marine annelids usually develop into free-swimming larvae. Eggs of terrestrial forms are enclosed in cocoons and hatch as miniature versions of the adults. The ability to regenerate lost body parts is highly developed in many polychaetes and digochaetes. Listing from Electric Library , a pay service.