What are the three classes of annelids?

Most authors accept the annelids as having three major classes: Polychaeta, Oligochaeta, and Hirudinea.

1. What are the three main groups of the annelids and their defining features?
2. What are the classes of annelids and how do you tell them apart?
3. Which of the following are the living classes within the phylum Arthropoda?
4. What are the two groups of annelids?
5. What are the main differences in reproduction among the three classes of annelids?
6. What are three types of segmented worms?
7. Why are annelids segmented?
8. What are 3 facts about segmented worms?
9. Are annelids a class or phylum?
10. How are segmented worms classified?
11. Are nematodes segmented?

What are the three main groups of the annelids and their defining features?

A major invertebrate phylum of the animal kingdom, the annelids number more than 9,000 species distributed among three classes: the marine worms (Polychaeta), which are divided into free-moving and sedentary, or tube-dwelling, forms; the earthworms (Oligochaeta); and the leeches (Hirudinea).

What are the classes of annelids and how do you tell them apart?

There are three classes of annelids: Class Polychaeta: marine annelids; Class Oligochaeta: marine, freshwater and terrestrial annelids including earthworms; Class Hirudinea: marine, fresh water and terrestrial leeches.

Which of the following are the living classes within the phylum Arthropoda?

The phylum Arthropoda is commonly divided into four subphyla of extant forms: Chelicerata (arachnids), Crustacea (crustaceans), Hexapoda (insects and springtails), and Myriapoda (millipedes and centipedes).

What are the two groups of annelids?

For the purposes of this concept, we will consider two main classes of annelids: Polychaetae and Clitellata. The Clitellata are characterized by the presence of a specialized reproductive organ called the clitellum.

What are the main differences in reproduction among the three classes of annelids?

Reproduction in annelids is a fairly complex topic. Polychaete and oligochaete species can reproduce both sexually and asexually, while leeches can only reproduce sexually. Asexual reproduction does not involve the formation of gametes (eggs and sperm), and it usually occurs either by budding or fission.

What are three types of segmented worms?

The phylum Annelida contains the segmented worms. Annelida is further divided into three subclasses: Oligochaeta, Hirudinea and Polychaeta. Thousands of species of segmented worms comprise these three subclasses.

Why are annelids segmented?

Annelids. Annelids contain largely segmented bodies with each segment containing elements of the different body systems essential for life, such as the nervous system. ... With annelids, the segmentation allows for more efficient body movement through the use of localized muscle contraction as part of the muscular system.

What are 3 facts about segmented worms?

The segmented worms are slender, generally cylinder-shaped creatures. They have a complete digestive tract: a mouth at one end, an anus at the other. Most species are equipped with setae—short, bristlelike hairs that extend from the body wall and function in locomotion.

Are annelids a class or phylum?

Classification of Phylum Annelida

Phylum Annelida contains the class Polychaeta (the polychaetes) and the class Oligochaeta (the earthworms, leeches and their relatives).

How are segmented worms classified?

Earthworms are segmented worms. Segmented worms are in the phylum Annelida, which has over 22,000 known species. These worms are known as the segmented worms because their bodies are segmented, or separated into repeating units. Besides the earthworm, the segmented worms also include leeches and some marine worms.

Are nematodes segmented?

With regards to morphology, nematodes are mostly non-segmented with a cylindrical cross-section with most of them being microscopic (less than one millimeter in length). ... While a good number of nematodes are free-living organisms, there are many parasitic species.