Annelids have what kind of body

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Source : Hickman, C. Animal Diversity. Brown, Dubuque, IA. Read more Classification Kingdom Animalia animals Animalia: information 1 Animalia: pictures Animalia: specimens Animalia: sounds Animalia: maps Annelida: information 1 Annelida: pictures Related Taxa Species Hirudo medicinalis Hirudo medicinalis: information 1 Hirudo medicinalis: pictures 1.

Lamellibrachia luymesi: information 1 Lamellibrachia luymesi: pictures 1. Polychaeta: information 1 Polychaeta: pictures Riftia pachyptila: information 1 Riftia pachyptila: pictures 1. Marine worms, mostly known as polychaetes, are also closely related, encompassing such animals as lugworms, clam worms, bristleworms, fire worms and sea mice. To our knowledge today, roughly 9, species of annelid exist, all following the same basic body plan.

As demonstrated by the earthworm body plan, annelids are long and lacking leg structures. These bristles, also called setae, project through the wall of the cuticle, or outer covering, A few marine worms, notably the calcerous tubeworm Serpula vermicularis also have feather-like radial appendages extending from the fronts of their bodies. Annelids are characterized by segments, which you can again see if you look at an earthworm.

The ridges running along the body mark where the inner cavity is segmented inside, forming individual sections of the circulatory, nervous and digestive systems. Each of these segments is called a somite, and by using muscles located in that specific area, can move independent of the other segments. Muscles run both the length of the body, and circularly around the circumference of the body. However, cross-fertilization is preferred in hermaphroditic animals.

These animals may also show simultaneous hermaphroditism and participate in simultaneous sperm exchange when they are aligned for copulation. Phylum Annelida contains the class Polychaeta the polychaetes and the class Oligochaeta the earthworms, leeches and their relatives. The many chetae of polychaetes are also arranged within fleshy, flat, paired appendages that protrude from each segment called parapodia , which may be specialized for different functions in the polychates.

The subclass Hirudinea includes leeches such as Hirudo medicinalis and Hemiclepsis marginata. The class Oligochaeta includes the subclass Hirudinia and the subclass Brachiobdella. A significant difference between leeches and other annelids is the development of suckers at the anterior and posterior ends and a lack of chaetae.

Additionally, the segmentation of the body wall may not correspond to the internal segmentation of the coelomic cavity. This adaptation possibly helps the leeches to elongate when they ingest copious quantities of blood from host vertebrates. The subclass Brachiobdella includes species like Branchiobdella balcanica sketi and Branchiobdella astaci , worms that show similarity with leeches as well as oligochaetes.

Figure 3. The a earthworm, b leech, and c featherduster are all annelids. Phylum Annelida includes vermiform, segmented animals. Segmentation is seen in internal anatomy as well, which is called metamerism. Annelids are protostomes. These animals have well-developed neuronal and digestive systems. Some species bear a specialized band of segments known as a clitellum. Annelids show the presence numerous chitinous projections termed chaetae, and polychaetes possess parapodia. Suckers are seen in order Hirudinea.