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How many species of annelida are there?
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).
Are centipedes annelids?
The Annelid phylum contains three classes of organisms: Polychaeta, Oligochaeta and Hirudinea. The Arthropoda phylum contains five classes: Crustacea (shrimp and lobster), Arachnida (spiders and scorpions), Chilopoda (centipedes), Diplopoda (millipedes) and Insecta (roaches and beetles).
What are the muscular fleshy appendages on some annelids?
Most annelids have external bristles called setae. Some annelids also have fleshy appendages called parapodia.
What are some facts about annelids?
Facts About Annelids. Annelids are the segmented worms like earthworms, ragworms and others that we see practically everywhere. Annelids are a species of worm that includes various other worms including leeches etc. There are about 17,000 varieties of species seen in different parts of the world.
What is the species of annelids?
The annelids ( Annelida , from Latin anellus, “little ring”), also known as the ringed worms or segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches.
What are the characteristics of annelids?
Characteristics of Annelids. The common characteristics of annelids are as follows: Annelids have a long cylindrical body. The body is segmented internally as well as externally. Bilaterally symmetrical. Vermiform. They are cephalopods. They have a true body cavity.
What is the segmentation of annelids?
Annelids. With annelids, the segmentation allows for more efficient body movement through the use of localized muscle contraction as part of the muscular system. Annelids have a highly developed internal segmented circulatory system that allows for efficient blood flow to muscles and critical body systems such as the circulatory system,…