41. The WhatUseek Directory - Acoelomates whatUseek offers a suite of online products and services including a web search utility, a web directory, siteLevel, changeAlarm, and more. http://dir.whatuseek.com/Science/Biology/Zoology/Acoelomates

Search The Directory The Web for Home Science Biology Zoology Acoelomates New! Submit a site Categories: Gnathostomulida Platyhelminthes Nemertea Rhombozoa whatUseek Collection Sites submit a site Give your site great placement in this category in as little as two business days! whatUseek Directory Site Listings: Acoelomates Animals - An introduction to the Platyhelminthes and Nemertea, with links to several images. Dugesia - The anatomy of the triclad turbellarian, commonly known as planaria. Only text, no pictures. Flatworms: British Marine Life Study Society - One page about a planarian and one page about the life cycle of the digenean Cryptocotyle lingua, with a few photographs. Introduction to the Nemertini - Introduction to the Nemertini, the ribbon worms. A short page with a single photograph. Introduction to the Platyhelminthes - Introduction to the Platyhelminthes, the flatworms: life in two dimensions. One page of text with a few photographs. Meiofauna - Matthew Hooge - A personal page with many beautiful photographs of free-living Platyhelminthes, including actin labelling. Monogenean Trematodes - A short page about monogeneans parasitic in fishes and how to control them. Also available as PDF file.

42. Chapter 25--Acoelomates And Pseudocoelomates Outline Ch. 25The Animals/Introducing the Invertebrates. I. What are animals? A. Eukaryotes B. multicellular, with specialized tissues C. heterotrophic http://www.asms.net/facultymanaged/bmcph/courses/apbio/apbiofiles/apnotes/ch25in

Outline: Ch. 25-The Animals/Introducing the Invertebrates I. What are animals? A. Eukaryotes B. multicellular, with specialized tissues C. heterotrophic D. no cell walls E. feed by ingestion; store food as glycogen and fat F. move by means of specialized cells containing contractile fibers (muscle tissue) II. Where from? A. Probably arose from heterotrophic protists. B. There may have been more than one independent origin of animals from protists: Ediacaran animals (all extinct) 2. Subkingdom Parazoa; Phylum Porifera (Sponges) 3. Subkingdom Mesozoa; Phylum Mesozoa (may be a primitive group or may be highly reduced flatworms) 4. Subkingdom Eumetazoa (modern animals) see table p. 520 C. A key issue is whether multicellularity resulted from amalgamation separate cells form colonies and become interdependent; or subdivision a single multinucleate cell develops internal separations and the separate compartments develop specialized roles. III. Describe the origin and defining characteristics of the major phyla. A. The major modern phyla are all considered

43. Body Cavity - Wikipedia, The Free Encyclopedia By the broadest definition, a body cavity is any fluid filled space in a multicellular organism. However, the term usually refers to the space, located between an animal ’s outer http://en.wikipedia.org/wiki/Body_cavity

Body cavity From Wikipedia, the free encyclopedia Jump to: navigation search Picture of Human body cavities — dorsal body cavity to the left and ventral body cavity to the right. By the broadest definition, a body cavity is any fluid filled space in a multicellular organism . However, the term usually refers to the space, located between an animal ’s outer covering ( epidermis ) and the outer lining of the gut cavity, where internal organs develop. "The body cavity" of the human body cavities normally refers to the ventral body cavity , because it is by far the largest one in volume. Contents Grouping Coelom Formation Origins ... edit Grouping The type of body cavity places an organism into one of three groups: Coelomates (also known as eucoelomates — "true coelom") have a fluid filled body cavity called a coelom (pronounced /ˈsiːləm/ ) with a complete lining called peritoneum derived from mesoderm (one of the three primary tissue layers ). The complete mesoderm lining allows organs to be attached to each other so that they can be suspended in a particular order while still being able to move freely within the cavity. Most bilateral animals, including all the vertebrates , are coelomates.

44. Reefs.org: Where Reefkeeping Begins On The Internet - Aquarium.Net Jan 97 Article outlining the biology of the Platyhelminthes and Nemertea. http://www.reefs.org/library/aquarium_net/0297/0297_5.html

@import url(http://www.reefs.org/ploneColumns.css); @import url(http://www.reefs.org/plone.css); @import url(http://www.reefs.org/ploneCustom.css); Skip to content News Contact Us SiteMap ... RSS Search Reefs.org: Where Reefkeeping Begins on the Internet Sections Home Forums Library Chat ... Sponsors Personal tools You are not logged in Log in Join You are here: Home Library Aquarium.Net Article Index Aquarium.Net Jan 97 Aquarium.Net Subject Index Cnidarians (corals) Fish Invertebrates Sandbeds ... General Information Aquarium.Net Jan 97 This month Rob continues his series on invertebrate zoology with Ribbon worms (Platyhelminthes and Nemertea)Aquarium Net has numerous articles written by the leading authors for the advanced aquarist Reefkeeper's Guide to Invertebrate Zoology Part 4: By Rob Toonen In the last article I tried to give a quick overview of some of the interesting and I think largely unknown details of Cnidarian biology. Notoplana sp. A flatworm about 3 cm long. There are eyespots visible near the anterior end. Photo by Ron Shimek This overview was far from comprehensive, but I tried to touch on some of the interesting research I have come across recently that I thought would be of general interest to hobbyists. Even though the article was longer than I intended, I still covered so little of the available information on cnidarians.

45. Coelomate Protostomes- Phylum Annelida Phylum Annelida http://bio.rutgers.edu/~gb102/lab_2/306am-annelid.html

46. Www.gwu.edu Evolution of Coelomate Animals In the cnidarians, the space between the ectoderm and endoderm tissue layers is filled with an acellular mesoglea. http://www.gwu.edu/~darwin/BiSc151/Coelom/Coelom.html

Evolution of Coelomate Animals In the cnidarians, the space between the ectoderm and endoderm tissue layers is filled with an acellular mesoglea. In the platyhelminthese (flatworms) mesoderm fills the space between mesoderm and the endoderm: The advantage of the flatworm body plan, is the superior pull muscles can make using solid mesoderm as a lever, versus gel-like mesoglea. Problems: 1. Body organs cannot move freely but are embedded in solid mesoderm tissue. 2. It is more difficult for materials to move from the gut to the body wall. A solution to both problems is to have some sort of body cavity, called a coelom , in which the body organs lie bathed in body fluid. Movement of the body wall would not squeeze the organs, organs could grow without being pressed by the body wall, and diffusion of nutrients and wastes would be easier. Advantages of a Coelom 1. The hydrostatic skeleton - a fluid-filled body cavity provids a more rigid structure than mesoderm for muscles to pull against and thus be a more efficient skeletal support system. Circulatory System Absorbed nutrients can be circulated around the body and metabolic wastes can be carried to the body surface more efficiently by fluid than by solid mesoderm.

47. Department Of Wildlife And Fisheries Sciences Department of Wildlife and Fisheries Sciences, http://www.sdstate.edu/wfs/

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