Segmented worms

Fig. 20 Cryo-TEM image of isolated micelles and segmented rods made from miktoarm ABC block copolymers containing PEO, PB and perfluorinated polyether blocks (scale bar is 50 nm). A schematic representation of the stacking of block copolymer chains in segmented worms is also shown. Reprinted with permission from [284], Copyright (2004) American Association for the Advancement of Science...

Annelid A member of the phylum Annelida, in general the segmented worms. 

The Annelida (segmented worms)131 are believed to be evolutionary antecedents of the arthropods. Present-day members include earthworms, leeches, and -105 species of marine polychaetes. Annelids have a true body cavity separate from the alimentary canal and lined by a peritoneum. They have a well-developed circulatory system and their blood usually contains a type of hemoglobin. 

Annelida (segmented worms) 24 Annexins 316,422, 571 Anomeric carbon atom 162 Anomeric effect 166 Antagonists 479 Antamanide 414... 

Annelida Segmented worms, leeches Body segmentation, complex organ systems marine, freshwater and terrestrial, some are parasites... 

As the major, organic, skeletal substance of invertebrates, chitin is found principally in the phyla Annelida (segmented worms), Arthropoda, and MoUusca, and, to a lesser extent, in Coelenterata and Nematoda (unsegmented worms). A critical compilation of the reported occurrences of chitin amongst these lower animals, especially the Arthropoda, has been made by Richards. This author reports that chitin has been found in the body wall... 

Yellow to reddish brown, slender, toughbodied, segmented worms up to I A" long feeding on roots and bulbs are wireworms. Adults are dark-colored, elongated click beetles. Apply parasitic nematodes to the soil before planting to control them. 

The populations of worms living in intertidal areas fall into two major groups flatworms and segmented worms. Of the... 

Segmented worms are much more advanced and complex than flatworms. The digestive systems of flatworms are one-way tubes sandwiched between two body walls. However, segmented worms have a space between their two body walls called the body cavity, or coelom, that represents an important evolutionary advance, one that provides a place for the body s internal organs. In segmented worms, organs are held in their proper places inside the coelom by a membrane, the peritoneum. 

Segmented worms have much more advanced digestive systems than flatworms do. A flatworm has one opening, a mouth, for food and wastes. A segmented worm has two openings, a mouth at one end and an anus at the other. The mouth opens to an esophagus that leads to a muscular pharynx. 

The evolutionary advancements from flat-worms to segmented worms are reflected in other animals such as mollusks and crustaceans, as well as in vertebrates. The segmented worms, although still evolutionarily simple, provided the groundwork from which further advancement evolved. 

Worms are plentiful in the shallow intertidal waters. Both simple flatworms and more complex segmented worms can be found there. Because of its size, the milky flatworm may be the most obvious, but the shoreline also supports many other types, including the speckled flatworm and oyster flatworm. 

Segmented worms are generally found along the bottom, living in deposits of sediment or under rocks. Some types build tubular homes for themselves in which they spend their entire lives. These sedentary worms include the parchment tube worm and the trumpet tube worm. Errant species, such as bloodworms and syllid worms, spend some of their time out of their hiding places, actively seeking prey. 

Less obvious, but just as numerous, are flatworms and segmented worms. Some species are free living, but many inhabit tubes just under the surface of the sand or mud. Crawling slowly among theses relatively simple animals are the larger arthropods—mollusks and echinoderms. 

The biological occurrence of hemerythrins (Hr in Figure 4.8), the third class of dioxygen carriers, is relatively rare, being restricted to the sipunculid family (nonsegmented worms), a few members of the annelid (segmented worm) fam-... 

The most important kinds of animals constituting the soil and litter fauna, according to Kevan (1962), are the Protozoa, nematodes, segmented worms and the great phylum of arthropods. 

Figure 15 Schematic drawing of (a) individual miktoarm star micelles and the stacking into a string and (b) side and end-on views of proposed chain packing for segmented worms. Reprinted from Li, Z. Kesselman, E. Talmon, Y. etal. ScienceZQQA, 306,98. ...

Fig. 10 Structure of a -((PEE)-(PEO)-(poly(/-methyl-e-caprolactone))) miktoarm block terpoly-mer, along with schematic representations and cryo-TEM micrographs of the resulting self-assembled micellar structures hamburger , segmented worm-like and raspberry micelles (from left to right). Reproduced with permission from [56]. Copyright (2008) American Chemical Society...

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