Worms

Worms are a diverse group of invertebrates that belong to the phylum Annelida. They can be found in various ecosystems, including freshwater, marine, and terrestrial environments. There are three main classes of worms: oligochaetes, polychaetes, and hirudineans.

Oligochaetes

Oligochaetes, such as earthworms, are characterized by the presence of bristles called setae along their body segments. They play a crucial role in soil ecosystems by aerating the soil and breaking down organic matter.

Polychaetes

Polychaetes are mostly marine worms and are known for their well-developed setae and parapodia, which are used for locomotion and respiration. They exhibit a wide range of feeding strategies, including filter feeding, scavenging, and predation.

Hirudineans

Hirudineans, commonly known as leeches, are characterized by their flattened bodies and sucker-like structures at both ends. They are mostly found in freshwater environments and are often blood-feeding parasites, although some species are predatory or scavengers.

Study Guide

1. What are the three main classes of worms?
2. Describe the role of oligochaetes in soil ecosystems.
3. What are parapodia, and which class of worms are they associated with?
4. Where are hirudineans commonly found, and what are their feeding habits?
5. Discuss the ecological importance of worms in their respective habitats.