Vertebrate animals

Vertebrates are those animals that have a backbone or a notochord, a primitive spine. Compared to the other animal phyla, there are relatively few species in the Phylum Chordata, only about 50,000. As humans and most of the animals associated with them are in this group, it is of interest beyond mere numbers. 

There are three subphyla within the Chordata. The first two are tunicates and amphioxus, both primitive, headless animals that will not be discussed here. The third group is the most highly developed and complex, the vertebrates or craniates (they have heads). The vertebrates have a segmented body, a cranium enclosing the brain, a heart, and a notochord or vertebral column. Other characteristics are not consistent, but most vertebrate species have bones of some kind, skin, at least two pairs of trunk appendages, and separate sexes. 

Within the Phylum Chordata, the subphylum vertebrata is divided into 

There are three orders within the class Amphibia. Order Anura is the largest of these, with over 5000 living species. This group includes frogs and toads. The order Urodela includes the 510 species of salamanders and their relatives. The smallest group is order Apoda, the caecilians, which are legless, blind, wormlike animals that borrow in the soil. 

Agnatha Hagfish, lampreys, slime eels The lowest animals having vertebrate characteristics marine eel-shaped jawless scavengers and parasites with notochord and cartilaginous fins and skeleton 

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DDT is slowly converted in vivo by reductive dechlorination to DDD and by further dechlorinations to 4,4 -dichlorodiphenylacetic acid [83-05-6] (DDA), the predominant excretory metaboUte. Anaerobically, it may form 4,4 -dichlorodiphenyiacetonitrile [20968-04-1] (DDCN). However, most DDT that enters the environment is sequestered as DDE, which is ubiquitously present in the body Hpids of invertebrate and vertebrate animals. In humans. 

Herbicides constitute a large and diverse class of pesticides that, with a few exceptions, have very low mammalian toxicity and have received relatively little attention as environmental pollutants. Much of the work in the held of ecotoxicology and much environmental risk assessment has focused on animals, especially vertebrate animals. There has perhaps been a tendency to overlook the importance of plants in the natural world. Most plants belong to the lowest trophic levels of ecosystems, and animals in higher trophic levels are absolutely dependent on them for their survival. 

Collagen is the most abundant animal protein in the body of animals, where it makes up as much as one-quarter of all the proteins. It is a fibrous protein that provides structure to and protects and supports soft tissues it also connects tissues to the skeleton. Collagen forms, for example, most of the resilient layers that make up the skin and the filaments that support the internal organs. Interwoven with bioinorganic components, collagen also makes up the bones and teeth of vertebrate animals (see Chapter 15). 

The bones and teeth of humans and other vertebrate animals, for example, consist mainly of a composite material made up of an organic substance, collagen, and a biomineral, calcium carbonate phosphate (see Textboxes 32 and 61). The latter, which makes up about two-thirds of the total dry weight of bone, is composed of calcium phosphate containing between 4-6% calcite (composed of calcium carbonate) as well as small amounts of sodium, magnesium, fluorine, and other trace elements. The formula Ca HPChXPChMCChXOH) approximately represents its composition its crystal structure is akin to that... 

Teeth, the hard conical structures embedded in their jaws that vertebrate animals use to chew food, consist of two layers of compact matter surrounding a core of soft, living tissue. The inner layer is composed of dentine, also known as ivory, whose composition is similar, but not identical, to that of bone it contains less collagen and is harder than bone. The thin outer layer of the teeth, the teeth s enamel, includes even less collagen and other organic matter than dentine and is the hardest substance produced by animals (Hilson 1986a Kurten 1986b 1982). 

Shostak, S. and Tammariello, R. V. (1969), Supernumerary heads in Hydra viridis, in C. J. Dawe and J. C. Harshbarger (Eds), Neoplasms and Related Disorders of Invertebrate and Lower Vertebrate Animals, National Cancer Institute Monograph, 31, 739-750. 

Chapters 9 and 10 while in this chapter we concentrate on cell-cell structures and their organic chemical communication and the very simple nerve networks between senses and muscles. At the same time a complicated series of organs became involved in intake, synthesis, distribution of material and waste excretion so as to supply suitable material with energy to the whole body and remove excess chemicals. Probably to protect and strengthen the structures, the invertebrates developed external shells but it is only with the arrival of vertebrates, animals with bones, that great internal structural strength with mobility evolved (see Figure 8.6 and Table 8.3). 

A total of 58 dead vertebrate animals (birds, amphibians, reptiles, mammals) were found on the first block, 39 on the second block, and 50 from the reference site. Authors concluded that risk to wildlife is low (Mortenson et al. 1999)... 

Figure 3. Rates of elimination of cyclodienes by aquatic vertebrates. Animals were transferred to clean water after maximum absorption in static systems (A), goldfish treated with photo-cis-chlordane (B), Xenopus with cis-chlordane (C), goldfish injected with heptachlor (D), goldfish with cis-chlordane (E), blue gills with photo-cis-chlordane (F), bluegills with photodieldrin and (G), cichlids with...

To reduce testing on vertebrate animals, data sharing is required for smdies on such animals. For other tests, data sharing is required on request. 

Xylanase production has been reported to occur in a wide spectrum of organisms. Although absent in vertebrate animals, xylanases are produced in many forms of bacteria, fungi and yeasts, crustaceans, algae and plant seeds. Current interest in xylanases has been focused primarily on the enzymes produced by fungi and bacteria and, to a lesser extent, yeasts. The high yields and relative ease of production have made these systems the most promising for future commercialization. 

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