The Phylum Annelida
Brief Overview
Annelida are invertebrate animals that possess a body cavity, movable bristles, and a body divided into segments. There are more than 9,000 species distributed among three classes: the marine worms, earthworms, and leeches. Annelida are found in all types of habitats, but especially in oceanic waters, fresh waters, and damp soils. The circulatory system in most animals in the Phylum Annelida contain a blood vessel that arises from the capillary network surrounding the intestine and conveys the blood forward, a vessel that conveys blood backwards, and a vessel that connects the two. The blood is spread through the capillary beds, and eventually splits into five hearts. Blood is moved through wavelike contractions of the vessels, provided by the heartbeat. Like Nematoda and Porifera, the circulatory system of Annelida is not very complex. However, it is somewhat evolved from the Nematoda and Porifera, as many species of Annelida has hearts, and the system is slightly more complex.
Annelida are invertebrate animals that possess a body cavity, movable bristles, and a body divided into segments. There are more than 9,000 species distributed among three classes: the marine worms, earthworms, and leeches. Annelida are found in all types of habitats, but especially in oceanic waters, fresh waters, and damp soils. The circulatory system in most animals in the Phylum Annelida contain a blood vessel that arises from the capillary network surrounding the intestine and conveys the blood forward, a vessel that conveys blood backwards, and a vessel that connects the two. The blood is spread through the capillary beds, and eventually splits into five hearts. Blood is moved through wavelike contractions of the vessels, provided by the heartbeat. Like Nematoda and Porifera, the circulatory system of Annelida is not very complex. However, it is somewhat evolved from the Nematoda and Porifera, as many species of Annelida has hearts, and the system is slightly more complex.
Hirundo medicinalis (Leeches)
Hirundo medicinalis is an amphibian leech, and resides exclusively in fresh water. In the circulatory system of Hirundo medicinalis, much of the space is filled with connective tissue. This leaves a series of interconnecting channels within the Hirundo medicinalis. Within the Hirundo medicinalis, the channels containing blood have taken over the internal transport, with movement only being induced by the contradiction of lateral channels.
Hirundo medicinalis is an amphibian leech, and resides exclusively in fresh water. In the circulatory system of Hirundo medicinalis, much of the space is filled with connective tissue. This leaves a series of interconnecting channels within the Hirundo medicinalis. Within the Hirundo medicinalis, the channels containing blood have taken over the internal transport, with movement only being induced by the contradiction of lateral channels.
Polychaeta nigra (Tube worms)
Polychaea nigra share many characteristics with other species in the Phylum Annelida. However, a major difference is the reversal of flow within its contractile vessels. These reversals in flow within the flow of blood essentially replace the capillary system within Polychaeta nigra. Polychaeta nigra play an important role in turning over bottom sediments in the sea.
Polychaea nigra share many characteristics with other species in the Phylum Annelida. However, a major difference is the reversal of flow within its contractile vessels. These reversals in flow within the flow of blood essentially replace the capillary system within Polychaeta nigra. Polychaeta nigra play an important role in turning over bottom sediments in the sea.
Lumbricus terrestris (Earth worm)
The circulatory system of an earth worm is more evolved than other species of annelida, due to the fact that its blood is confined only to its blood vessels, and its blood is reused, in order to get the most use out of it. The oxygen is taken in by the dorsal blood vessel and traves to the five aortic hearts, where it is pumped to the lower vessel. The ventral blood vessel pumps the blood to all segments and organs in need of oxygen.
The circulatory system of an earth worm is more evolved than other species of annelida, due to the fact that its blood is confined only to its blood vessels, and its blood is reused, in order to get the most use out of it. The oxygen is taken in by the dorsal blood vessel and traves to the five aortic hearts, where it is pumped to the lower vessel. The ventral blood vessel pumps the blood to all segments and organs in need of oxygen.