Cross-section of an earthworm.
Monday, March 5, 2007
Vocabulary
Annelid: round tubular animal that has a long segmented body. Belongs to phylum Annelida. Triploblastic.
Polychaetes: literally meaning "many-bristled", they are segmented worms (usually aquatic) characterized by laterally paired appendages on its body segments and a "spiky" body.
Oligochaeta: Annelid worm. The class that contains the common earthworm and related species that live in soil and in water. Literally means, "few-bristled".
Leech: Annelid worm. Typically exists as an external parasite that drinks the blood and body fluids of its host. Hooks on using mouth, and can drink up to 10x their weight.
Longitudinal muscles: Runs from the anterior of the worm to the posterior. When these muscle contract they make the worm shorter.
Circular Muscles: Muscles that run throughout the worm like a coil. When contraction occurs, worm elongates.
Septa: Plural of Septum. means, "Something that encloses." A wall separating the segments in an Annelid.
Nephridia: Plural of Nephridium. the excretory organ of many invertebrates, consisting of a tubule with one end opening into the body cavity and the other opening into a pore at the body surface.
Sanguivorous: Literally means, "that which eats blood" or something to that effect. Means blood-feeding, or blood eating.
Lumbriculus: A division of Oligochaeta
Aulophorus: A division of Oligochaeta
Hermaphroditic: An organism with both male and female reproductive organs.
Copulation: Sexual Intercourse.
Spermathecae: a small sac or cavity in hermaphroditic invertebrates used to store sperm for fertilizing eggs, such as in earthworms.
Clitellum: It secretes a mucus ring into which egg and sperm are released.
Pharynx: muscular front end of the digestive tube which can be extend to get food.
Triploblastic: Having three germ layers.
Coelom: A body cavity completely surrounded by mesoderm.
Annuli: In this case (earthworms), a ring mark.
Trochozoa: Full name is Lophotrochozoa; one of 3 major groups of protosome animal.
Polychaetes: literally meaning "many-bristled", they are segmented worms (usually aquatic) characterized by laterally paired appendages on its body segments and a "spiky" body.
Oligochaeta: Annelid worm. The class that contains the common earthworm and related species that live in soil and in water. Literally means, "few-bristled".
Leech: Annelid worm. Typically exists as an external parasite that drinks the blood and body fluids of its host. Hooks on using mouth, and can drink up to 10x their weight.
Longitudinal muscles: Runs from the anterior of the worm to the posterior. When these muscle contract they make the worm shorter.
Circular Muscles: Muscles that run throughout the worm like a coil. When contraction occurs, worm elongates.
Septa: Plural of Septum. means, "Something that encloses." A wall separating the segments in an Annelid.
Nephridia: Plural of Nephridium. the excretory organ of many invertebrates, consisting of a tubule with one end opening into the body cavity and the other opening into a pore at the body surface.
Sanguivorous: Literally means, "that which eats blood" or something to that effect. Means blood-feeding, or blood eating.
Lumbriculus: A division of Oligochaeta
Aulophorus: A division of Oligochaeta
Hermaphroditic: An organism with both male and female reproductive organs.
Copulation: Sexual Intercourse.
Spermathecae: a small sac or cavity in hermaphroditic invertebrates used to store sperm for fertilizing eggs, such as in earthworms.
Clitellum: It secretes a mucus ring into which egg and sperm are released.
Pharynx: muscular front end of the digestive tube which can be extend to get food.
Triploblastic: Having three germ layers.
Coelom: A body cavity completely surrounded by mesoderm.
Annuli: In this case (earthworms), a ring mark.
Trochozoa: Full name is Lophotrochozoa; one of 3 major groups of protosome animal.
Circulation/internal transport.
-Because of the flatworm’s shape they don’t have a circulatory or respiratory systems.
-Flatworms use diffusion to transport oxygen and nutrients throughout their body
-ex in an earthworm the circulation system is in a series of closed vessels, the two main vessels are the dorsal and ventral blood vessels. In the dorsal vessel the blood moves towards the anterior and in the dorsal vessel the blood moves towards the posterior.
-Flatworms use diffusion to transport oxygen and nutrients throughout their body
-ex in an earthworm the circulation system is in a series of closed vessels, the two main vessels are the dorsal and ventral blood vessels. In the dorsal vessel the blood moves towards the anterior and in the dorsal vessel the blood moves towards the posterior.
Relations to Other Phyla
Annelids have several relations to other phyla, such as the Arthropods and the Molluscs.
Arthropods are considered the closest relatives of the Annelids, due to their similar/common segmented body structures, but seem quite different otherwise. It is assumed that they undrwent convergent evolution to create the grouping of Articula. The only differences between them are that Arthropods have an open circulatory system, a respiratory system (with a trachea, gills or book lung), excretory glands, normally sexual activity, and an exoskeleton.
Molluscs share with the Annelids the trocophore larvae stage, as it is present in both groups. It's due to this that the Annelids and the Molluscs are grouped together as the Trochozoa. The Molluscs and the Annelids are different only in the fact that the Molluscs have an open circulatory system, a respiratory system, have a well developed brain, and have a nerve network in their body walls.
Arthropods are considered the closest relatives of the Annelids, due to their similar/common segmented body structures, but seem quite different otherwise. It is assumed that they undrwent convergent evolution to create the grouping of Articula. The only differences between them are that Arthropods have an open circulatory system, a respiratory system (with a trachea, gills or book lung), excretory glands, normally sexual activity, and an exoskeleton.
Molluscs share with the Annelids the trocophore larvae stage, as it is present in both groups. It's due to this that the Annelids and the Molluscs are grouped together as the Trochozoa. The Molluscs and the Annelids are different only in the fact that the Molluscs have an open circulatory system, a respiratory system, have a well developed brain, and have a nerve network in their body walls.
Advantages and Disadvantages (of Movement)
The disadvantage of this sort of movement is that on land and in water, the annelids are very slow. So slow that the ones on land are preyed upon often, and thus spend most of their time underground, only popping up occasionally. The ones in the water are slightly better off, as they can move a bit faster, but still spend most of their time hiding or burrowed in the ground.
An advantage is that this sort of movement allows for them to eat while they move, a trait that must come in handy. For example, the earthworm must ingest the soil as moves through the soil, otherwise it can not make much headway. The earthworm then poops it out, and in that process, made the soil richer and more fertile. Without this need, the earth would be pretty barren, as earthworms help the soil become more rich wherever they go.
An advantage is that this sort of movement allows for them to eat while they move, a trait that must come in handy. For example, the earthworm must ingest the soil as moves through the soil, otherwise it can not make much headway. The earthworm then poops it out, and in that process, made the soil richer and more fertile. Without this need, the earth would be pretty barren, as earthworms help the soil become more rich wherever they go.
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