Earthworm Anatomy and Physiology

This document describes the anatomy and physiology of earthworms, a type of segmented worm. The document includes information on the external and internal structures of earthworms, as well as their nervous system, excretory system, and reproductive system.

Questions

• What are the external features of an earthworm?
• What are the internal structures of an earthworm?
• How does the nervous system of an earthworm work?
• What is the excretory system of an earthworm?
• How do earthworms reproduce?

Answers

• The external features of an earthworm include a prostomium, mouth, clitellum, anus, and paired setae on each segment.
• The internal structures of an earthworm include the pharynx, esophagus, crop, gizzard, intestine, ventral nerve cord, septae between segments, seminal vesicles, seminal receptacles, dorsal blood vessel, aortic arches (=hearts), and nephridia.
• The nervous system of an earthworm is a ventral nerve cord with segmented ganglia.
• The excretory system of an earthworm consists of nephridia, which are tubular structures that remove waste products from the body.
• Earthworms reproduce sexually. Males and females exchange sperm, which is stored in the seminal vesicles of the female. The eggs are fertilized in the uterus and then laid in cocoons.