Chelicerates (Chelicerata)

Chelicerates (Chelicerata) Chelicerates (Chelicerata) are a group of arthropods that includes harvestmen, scorpions, mites, spiders, horseshoe crabs, sea spiders, and ticks. There are about 77,000 living species of chelicerates. Chelicerates have two body segments (tagmenta) and six pairs of appendages. Four pairs of appendages are used for walking and two (the chelicerae and the pedipalps) are used as mouthparts. Chelicerates have no mandibles and no antennae. Chelicerates are an ancient group of arthropods that first evolved about 500 million years ago. Early members of the group included the giant water scorpions which were the largest of all arthropods, measuring up to 3 meters in length. The closest living cousins to giant water scorpions are the horseshoe crabs. Early chelicerates were predatory arthropods, but modern chelicerates have diversified to take advantage of a variety of feeding strategies. Members of this group are herbivores, detritivores, predators, parasites, and scavengers. Most chelicerates suck liquid food from their prey. Many chelicerates (such as scorpions and spiders) are unable to eat solid food due to their narrow gut. Instead, they must expel digestive enzymes onto their prey. The prey liquifies and they can then ingest the food. The exoskeleton of a chelicerate is a hard external structure made of chitin that protects the arthropod, prevents desiccation, and provides structural support. Since the exoskeleton is rigid, it cannot grow with the animal and must be molted periodically to allow for increases in size. After molting, a new exoskeleton is secreted by the epidermis. Muscles connect to the exoskeleton and enable the animal to control the movement of its joints. Key Characteristics six pairs of appendages and two body segmentschelicerae and pedipalpsno mandibles and no antennae Classification Chelicerates are classified within the following taxonomic hierarchy: Animals Invertebrates Arthropods Chelicerates Chelicerates are divided into the following taxonomic groups: Horseshoe crabs (Merostomata) - There are five species of horseshoe crabs alive today. Members of this group live in shallow marine waters along the Atlantic coast of North America. Horseshoe crabs are an ancient group of chelicerates that date back to the Cambrian. Horseshoe crabs have a distinct and unsegmented carapace (hard dorsal shell) and a long telson (a spine-like tailpiece).Sea spiders (Pycnogonida) - There are about 1300 species of sea spiders alive today. Members of this group have four pairs of very thin walking legs, a small abdomen, and elongated cephalothorax. Sea spiders are marine arthropods that feed on nutrients of other soft-bodied marine invertebrates. Sea spiders have a proboscis that enables them to obtain food from prey.Arachnids (Arachnida) - There are more than 80,000 species of arachnids alive today (scientists estimate that there might be more than 100,00 living species). Members of this group include spiders, scorpions, whip scorpions, ticks, mites, pseu doscorpions, and harvestmen. Most arachnids feed on insects and other small invertebrates. Arachnids kill their prey using their chelicerae and pedipalps. Sources Hickman C, Roberts L, Keen S. Animal Diversity. 6th ed. New York: McGraw Hill; 2012. 479 p. Ruppert E, Fox R, Barnes R. Invertebrate  Zoology: A Functional Evolutionary Approach. 7th ed. Belmont CA: Brooks/Cole; 2004. 963 p.

Who Popularized the term Talented Tenth

Who Popularized the term 'Talented Tenth'   How was the term Talented Tenth popularized?   Despite social inequalities and Jim Crow Era laws that became a way of life for African-Americans in the South after the Reconstruction period, a small group of African-Americans were forging ahead by establishing businesses and becoming educated. A debate began amongst African-American intellectuals concerning the best way for African-American communities to survive racism and social injustice in the United States. In 1903, sociologist, historian, and civil rights activist W.E.B. Du Bois responded through his essay The Talented Tenth. In the essay, Du Bois argued: The Negro race, like all races, is going to be saved by its exceptional men. The problem of education, then, among Negroes must first of all deal with the Talented Tenth; it is the problem of developing the Best of this race that they may guide the Mass away from the contamination and death of the Worst.† With the publication of this essay, the term â€Å"Talented Tenth† became popularized. It was not Du Bois who first developed the term. The concept of the Talented Tenth was developed by the American Baptist Home Mission Society in 1896.   The American Baptist Home Mission Society was an organization comprised of Northern white philanthropists such as John D. Rockefeller. The purpose of the group was to help establish African-American colleges in the South to train educators and other professionals. Booker T. Washington also referred to the term â€Å"Talented Tenth† in 1903. Washington edited The Negro Problem, a collection of essays written by other African-American leaders in support of Washington’s position. Washington wrote: The Negro race, like all races, is going to be saved by its exceptional men. The problem of education, then, among Negroes must first of all deal with the Talented Tenth; it is the problem of developing the Best of this race that they may guide the Mass away from the contamination and death of the Worst, in their own and other races. Yet Du Bois defined the term, â€Å"Talented Tenth† to argue that one out of 10 African-American men could become leaders in the United States and the world if they pursued education, published books and advocated for social change in society. Du Bois believed that African-Americans really needed to pursue a traditional education versus the industrial education that Washington consistently promoted. Du Bois argued in his essay: â€Å"Men we shall have only as we make manhood the object of the work of the schools - intelligence, broad sympathy, knowledge of the world that was and is, and of the relation of men to it - this is the curriculum of that Higher Education which must underlie true life. On this foundation we may build bread winning, skill of hand and quickness of brain, with never a fear lest the child and man mistake the means of living for the object of life.† Who were examples of the Talented Tenth? Perhaps two of the greatest examples of the Talented Tenth were Du Bois and Washington. However, there were other examples: The National Business League, established by Washington brought together African-American businessowners across the United States. The American Negro Academy, the first organization in the United States with the purpose of promoting African-American scholarship. Founded in 1897, the use of The American Negro Academy to promote the academic achievements of African-Americans in areas such as higher education, arts, and science.The National Association of Colored Women (NACW). Established in 1986 by educated African-American women, the purpose of the NACW was to fight sexism, racism, and social injustice.The Niagara Movement. Developed by Du Bois and William Monroe Trotter in 1905, the Niagara Movement led the way for the NAACP to be established.