Polychaetes, Oligoquetas and Hirudíneos

Earthworm: Example of oligoquette annelid

What are

The polychaetes, oligochaetes and hirudines are classes of annelid animals.


It is the annelids that have as their main feature the existence of many bristles (parapodes) in the lateral regions of the body.

Most polychaetes live in the sea and some species have freshwater as their habitat.

Polychaetes, unlike oligochaetes, have no clitella. Most of these annelids are of separate sexes. There are larval phases during the development process.

Examples: Phyllodoce rosea and Phyllodoce lineata


They are annelids that have few bristles on the body. Some species are marine while others live on land. The oligochaetes are hermaphroditic and can reproduce asexually or sexually. The fecundation of these annelids is crossed, presenting direct development.

The oligoquetas have in the epidermis the clitelo, whose function is to manufacture a cocoon that keeps the fertilized eggs during the reproduction.

Example: Earthworm (lumbricus terrestris)


These are annelids whose main feature is the presence of a suction cup around the mouth and the back of the body. These annelids have no bristles and the clit is undeveloped.

Hirudines are hermaphrodites. Fertilization of these annelids is crossed and development is direct.

Example: Leech (hirudo medicinalis)

Leech: example of hirudinous annelid.