Topics: Annelid, Phylum, Earthworm Pages: 5 (1152 words) Published: August 25, 2013
Interesting Facts-Annelida
The most recognized image of
feeding arms, and mouth of a jellyfish.
There are only about 200 species of

Vocabulary- Cnidaria
Aboral end: The opposite side of the oral end.
Anthozoa: The class of the Coelenterata which includes the corals and sea anemones. •Cnidocytes: unique cells that function in defense and the capture of prey. •Cubozoa: Any of
Animals in

FIGURES- Cnidaria

Evolutionary History

Diagrams of Cnidaria

Life Cycle - Cnidaria

The diagrams above show the general life cycle of the Cnidaria phylum. As shown above, the life cycle is dominated by the diploid cells as in most animals, while the haploid cells are only in early developmental stages. The life cycles also illustrate the change from a polyp (child) to a medusa (adult) from stage to stage.

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The phylum Annelida derives its name from the Latin word “annelus” which translates to “little ringed.” Annelids may be commonly referred to, or identified as, segmented worms. Annelida consists of over 17,000 different species which range in size from less than a millimeter to the Australian earthworm which may exceed 3 meters in length. The habits where one may encounter segmented worms range from a freshwater pond, to an undersea hydrothermal vent, to the damp soil in one’s back yard. Annelida is separated into three major classes. Polychaeta whose name means “many hairs” mostly live in a marine biome and have parapodia that they use for locomotion. The common earthworm most familiar to us belongs in the class Oligochaeta. Annelids of this class do not possess parapodia but chaetae bristle that the worm uses for traction to move. Perhaps the most abhorred class, Hirundinea, is composed of Annelids more commonly known as leeches. The majorities of leeches live in freshwater habitats and may either feast upon other smaller invertebrates or take on a parasitic role and feed from a larger host. The key difference between worms of Annelida and Platyhelminthes is that the bodies of Annelids are composed of nearly identical segments. Each segment is separated by a thin tissue called a septum. A pair of excretory tubes called metanephridium is located in each segment and removes waste and coelomic fluid out through exterior pores on the skin. Running throughout the length of the worm is the animal’s intestine which stretches from the creature’s mouth to its anus as well as nerve running adjacent to the intestine which stretching from the tail to the cerebral ganglia located at the head. The majority of Annelids like flat worms respirate via the skin, however some species possess gills where exposed blood...
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