Sunday, May 17, 2020
How Many Animal Species Are There
Everyone wants hard figures, but the fact is that estimating the number of animal species that inhabit our planet is an exercise in educated guesswork. The challenges are numerous. Species counts are biased by our tendency to study certain organisms more than others. Birds, as a group, have been extensively studied, so scientists believe that the estimated number of bird species alive today (between 9,000 to 10,000) is a relatively good approximation of the actual number. On the other hand, nematodes, also known as roundworms, are a little-studied group of invertebrates and consequently, we have little grasp of how diverse they may be. Habitat can make counting animals difficult. Animals that live in the deep sea are not easy to access, so naturalists have less understanding of their diversity. Organisms that inhabit the soil or parasitize other animals are likewise challenging to locate and therefore difficult to quantify. Even terrestrial habitats, like the Amazon rainforest, can present insurmountable obstacles to a species census. Animal size often complicates the detection and counting of species. In many instances, the smaller species are more difficult to find and count. Ambiguities in terminology and scientific classification affect species counts. How do you define a species? Its not always easy, especially when supposed species are capable of cross-breeding. Additionally, different approaches to classification influence species counts. For example, some models classify birds as reptiles, thus boosting the species count of reptiles by as much as 10,000. Despite these challenges, its desirable to have some idea of how many species inhabit our planet. This gives us the perspective necessary to balance research and conservation objectives, to ensure that less popular groups of animals are not overlooked, and to help us better understand community structure and dynamics. Rough Estimates of Animal Species Numbers The estimated number of animal species on our planet falls somewhere in the vast range of three to 30 million. How do we come up with that whopping estimate? Lets take a look at the major groups of animals to see how many species fall within the various categories. If we were to divide all the animals on earth into two groups, invertebrates and vertebrates, an estimated 97% of all species would be invertebrates. Invertebrates, animals that lack backbones, include sponges, cnidarians, mollusks, platyhelminths, annelids, arthropods, and insects, among other animals. Of all invertebrates, the insects are by far the most numerous. There are so many insect species, at least 10 million, that scientists have yet to discover them all, let alone name or count them. Vertebrate animals, including fish, amphibians, reptiles, birds, and mammals, represent a puny 3% of all living species. The list below provides estimates of the number of species within the various animal groups. Keep in mind that the sub-levels in this list reflect the taxonomic relationships between organisms. This means, for example, that the number of invertebrates species includes all the groups below it in the hierarchy (sponges, cnidarians, etc). Since not all groups are listed below, the number of a parent group is not necessarily the sum of child groups. Animals: estimated 3-30 million species||--Invertebrates: 97% of all known species|   |--Sponges: 10,000 species|        |--Cnidarians: 8,000-9,000 species|        |--Mollusks: 100,000 species|        |--Platyhelminths: 13,000 species|        |--Nematodes: 20,000 species|        |--Echinoderms: 6,000 species|        |--Annelida: 12,000 species|        |--Arthropods|            |--Crustaceans: 40,000 species|                 |--Insects: 1-30 million species|                 |--Arachnids: 75,500 species||--Vertebrates: 3% of all known species|--Reptiles: 7,984 species|--Amphibians: 5,400 species|--Birds: 9,000-10,000 species|--Mammals: 4,475-5,000 species|--Ray-Finned Fishes: 23,500 species Edited by Bob Strauss
Wednesday, May 6, 2020
Ns325-02 Nutrition Across the Human Life Cycle Essay
Final Project - 1 Unit 9 Final Project April Polasek Nutrition across the Human Life Cycle NS 325-02 Nancy Mears November 21, 2011 Final Project - 1 Unit 9 Final Project I would like to start this paper by stating that I have been on a low calorie diet for the past 3 weeks so if my foods seem like they are similar daily this is the reason why. I usually have a pretty healthy diet because nutrition is very important to me and for my children. I try to make sure that my children eat as healthy as possible and get the physical activity that need on a daily basis. In my assessment through Fitday.com my current diet consist of the foods that I have†¦show more content†¦I was really surprised that there were so many nutrients that I did not meet the recommended dietary allowance. I am unclear on Vitamin B12 because it has my intake at 2.4 mcg and the RDA was 2.4 my percentage was in the red at 99%. I did not meet my Vitamin C recommendations and I was in the red at 97%, I did not meet the recommendations for Vitamin D and I was in the red at 1%. Vitamin E is another area that I was in the red at 29%, Calcium I was in the red at 65%, Copper in the red at 94%, Iron I was in the red at 35%, Magnesium in the red at 60%, Manganese I was in the red at 78%, Potassium I was in the red at 51%, Thiamin I was in the red at 50 %, and Zinc in the red at 89%. The nutrients that I consumed too much in were Vitamin A at 107%, Vitamin B6 at 124%, Niacin at 131%, phosphorus at 128 %, Riboflavin at 132 %, Sodium at 115 %. I know that when I consume too much sodium in my diet my hands get real swollen so it is very easy for me to know the effects of too much sodium. I really try not to cook with very much salt and I never re-salt my food just for the simple fact that I know how bad it can be for your health. I do not know what the effects could be for consuming too much of the other nutrients. On the nutrients that I did not get enough of Calcium and Vitamin D being among the list of many I know that it is because I do not consume
Hegemonic Masculinity in Sociology Text free essay sample
A discussion on how the topic of hegemonic masculinity is presented in three sociology texts. This paper discusses hegemonic masculinity which is defined as masculinity constructed in relation to the various subordinate masculinities as well as in relation to women. The paper shows how this topic is demonstrated in three sociology texts: Riding The Bull at Gilleys by Scully and Marolla, Selling Crack by Anderson, and Fraternities and Rape on Campus by Martin and Hummer. The paper shows that these articles name hegemonic masculinity as one of the main culprits to the social problem they address. Many offenders believe that they have the right, because they are men, to discipline and punish women. Rape is used to put women in their place. Thus the men prove their manhood. The most disturbing scenario involves the idea of an added bonus. The men in these situations were burglarizing a residence and figured why not rape the homeowner, after realizing they were in control of the situation. We will write a custom essay sample on Hegemonic Masculinity in Sociology Text or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The last type of rape was that of sexual access. When a woman was unwilling or unavailable, the rapist is able to seize what is not offered, rape of conquest. Many of these rapes involve white victims and black perpetrators. Overall, most of the rapists suggest that they believe their victims deserved being raped or were asking for it. Many also felt that they had not committed a crime at all. In the final analysis, it was found that dominance was the objective of most rapes. To dominate a subordinate group in order to prove his masculinity, a man is engaging in a show of hegemonic masculinity.
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