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12: Diverstity of Animals - Biology

12: Diverstity of Animals - Biology



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  • 12.1: Features of the Animal Kingdom
    Animals constitute a diverse kingdom of organisms. Although animals range in complexity from simple sea sponges to human beings, most members share certain features. Animals are eukaryotic, multicellular, heterotrophic organisms that ingest their food and usually develop into motile creatures with a fixed body plan. Most members of the animal kingdom have differentiated tissues of four main classes—nervous, muscular, connective, and epithelial—that are specialized to perform different functions.
  • 12.2: Sponges and Cnidarians
    Animals included in phylum Porifera are parazoans and do not possess true tissues. These organisms show a simple organization. Sponges have multiple cell types that are geared toward executing various metabolic functions. Cnidarians have outer and inner tissue layers sandwiching a noncellular mesoglea. Cnidarians possess a well-formed digestive system and carry out extracellular digestion. The cnidocyte is a specialized cell for delivering toxins to prey and predators.
  • 12.3: Flatworms, Nematodes, and Arthropods
    Flatworms are acoelomate, triploblastic animals. They lack circulatory and respiratory systems, and have a rudimentary excretory system. The digestive system is incomplete in most species. There are four traditional classes of flatworms, the largely free-living turbellarians, the ectoparasitic monogeneans, and the endoparasitic trematodes and cestodes. Trematodes have complex life cycles involving a secondary mollusk host and a primary host in which sexual reproduction takes place.
  • 12.4: Mollusks and Annelids
    The phylum Mollusca is a large, mainly marine group of invertebrates. Mollusks show a variety of morphologies. Many mollusks secrete a calcareous shell for protection, but in other species, the shell is reduced or absent. Mollusks are protostomes. The dorsal epidermis in mollusks is modified to form the mantle, which encloses the mantle cavity and visceral organs. This cavity is distinct from the coelomic cavity, which the adult animal retains, surrounding the heart.
  • 12.5: Echinoderms and Chordates
    Echinoderms are deuterostome marine organisms. This phylum of animals bear a calcareous endoskeleton composed of ossicles covered by a spiny skin. Echinoderms possess a water-based circulatory system. The madreporite is the point of entry and exit for water for the water vascular system. The characteristic features of Chordata are a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. Chordata contains two clades of invertebrates together with the vertebrates.
  • 12.6: Vertebrates
    The earliest vertebrates that diverged from the invertebrate chordates were the jawless fishes. Hagfishes are eel-like scavengers that feed on dead invertebrates and other fishes. Lampreys are characterized by a toothed, funnel-like sucking mouth, and some species are parasitic on other fishes. Gnathostomes include the jawed fishes (cartilaginous and bony fishes) as well as all other tetrapods. Cartilaginous fishes include sharks, rays, skates, and ghost sharks.

12: Diverstity of Animals - Biology

The Evolution of animal diversity

Animal Diversity
Diversity is the abundance in the number of species in a given location. Most animal phyla are invertebrates. Extant (living) animals are divided into 35 phyla. Phyla are split according to their adult and embryological forms. First spilt in evolution is Parazoa and Eumetazoa. Parazoa do not possess true organelles and their body parts are primitive. Eumetazoa have well developed tissues and organs. Animals under radiata have radial symmetry and are diploblastic. Animals under bilateria are bilateral in symmetry and are triploblastic. Many animals such as humans are symmetrical. Acoelomates do not have body cavity, while coelomates have it. Pseudocoelomates have a false cavity.

Animal Evolution
Embryological changes take place during evolution. Gastrulation is the differentiation of animal tissues into germinal layers. Bilaterally symmetrical animals produce three germ layers: Ectoderm, Endoderm and Mesoderm. Ectoderm becomes the outer surface and nervous tissue of animals. Mesoderm becomes muscle, skeletal and connective tissue. Endoderm becomes the lining of the digestive gut. Diploblastic animals (Cnidaria and Ctenophora) have only endoderm and ectoderm. Platyhelminths, Nematodes, Rotifers, Mollusks, Arthropods and Chordates are triploblastic animals with three germinal layers.

Cambrian Explosion
All surviving animals today can be traced back to their ancestors to this time period. About 500 million years ago extant animal body plans were identified on fossil records. Hard body parts were easily identified from the records. Animal diversity has been developed due to increased dependency or the predatory/prey relationship, development of jeans to assist embryonic development and adequate environment oxygen to support active animal lifestyle.

Animal Classification
Sponges are marine animals, live singly and attach to a substrate. Coelenterates exhibit radial symmetry. There are three major groups of flatworms: Planarians, flukes and tapeworms. Round worms have false body cavity which gives shape to the worms. Mollusks have two circulatory systems, bilateral symmetry, complete digestive tract and internal organs. Segmented worms have nervous, circulatory and excretory systems in each segment. Insects belong to the most successful phyla &ndash Arthropoda. They are segmented, have jointed appendages and have an exoskeleton composed of chitin. Starfishes are slow moving animals and have unique water vascular system. Vertebrates have a backbone or a vertebral column, humans belong to this phylum.

The continuous genetic change in organisms that results from their adaptation, by natural selection to ever changing environments is called evolution. Animals are heterotrophic, eukaryotic and multicellular. Diversity is the abundance in the number of species in a given location. Most animal phyla are invertebrates. Extant (living) animals are divided into 35 phyla. Many animals such as humans are symmetrical. Acoelomates do not have body cavity, while coelomates have it. Pseudocoelomates have a false cavity. Embryological changes take place during evolution. Gastrulation is the differentiation of animal tissues into germinal layers. Bilaterally symmetrical animals produce three germ layers: Ectoderm, Endoderm and Mesoderm. About 500 million years ago extant animal body plans were identified on fossil records. Hard body parts were easily identified from the records. Animal classification has been discussed with each phylum and corresponding examples. Humans belong to the phylum Chordata.

  • General concept map of animal evolution to show the evolution process
  • Concept map to depict the characteristics of animals, animal embryology and animal birth.
  • Flow charts are shown to simplify the aspects
  • Each phylum has an example with a picture.
  • Introduction
  • Characteristics of animals
  • Basic features
  • Animal organ system
  • Animal body fluids
  • Introduction
  • Splitting of Phyla
  • Parazoa Vs. Eumetazoa
  • Radiata Vs. Bilateria
  • Acoelomates Vs. Coelomates
  • Protosomes Vs. Deuterosomes
  • Introduction
  • Gastrulation
  • Animal Embryology
  • Animal Birth
  • Evolution
  • Diploblastic & Triploblastic Animals
  • Introduction
  • Cambrian Explosion
  • Explosive Evolution
  • Expansion of Animal Diversity
  • Porifera
  • Cnidaria
  • Platyhelmenthes
  • Nematoda
  • Molluscs
  • Annelida
  • Arthropoda
  • Eichinodermata
  • Chordata

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Books, Bytes, and a Few Other Things

Animal University Web by UM Museum of Zoology
Format/Length: Database
Genre/Subject(s): Nonfiction, animals, biology, learning, natural history, science
Age Range: High school (Grades 9-12)
Publishing Info: Online : University of Michigan Museum of Zoology, c2008.
Awards: Digital Dozen Exemplary Web Site for Science and Math Educators (2005) featured in Scout Report for Science & Engineering’s biweekly collections of Internet sites for researchers, educators, and students in the life sciences, physical sciences, and engineering (2005) Scientific American Sci/Tech Web Award (2003) and several more.
Website Link Rating: ★★★★

Short Summary: The University of Michigan Museum of Zoology’s Animal Diversity Web is “an online database of animal natural history, distribution, classification, and conservation biology.”

Review: Animal Diversity Web provides almost comprehensive coverage of the numerous animal species provided throughout the world. The database contains over 2,000 animal species accounts, over 11,000 images, and more than 700 animal sounds. There also several hundred QuickTime movies of animal skulls (mostly mammals’) that can be rotated to get an idea of the skulls’ 3-D structure, and these are marked by an icon of 3-D glasses below a screencap in the species pages’ image sections. This content is searchable and consistent across species’ pages to allow for easy comparison and contrast. Each species’ hierarchical information is displayed at the top of its page as well as in a box to the side at the beginning. Quite a bit of information is contained in each species’ page, making it a good biology resource for students.

Animal Diversity Web (ADW) provides a nice depth of coverage for individual species. The consistency of format across pages makes it easy for users to know what information to expect and to find what they want fairly easily. The information on species pages has been produced by students for college classes, and although the Overview page claims to not be able to guarantee the pages’ accuracy, instructors and ADW staff do review and edit them before adding them to the site. Hierarchies above species level are written by professional biologists. Citations are provided for the information contained in the species pages, and a citation for each individual page of the database is also provided, which is especially handy for students using it for assignments. Some pages are older than others, as the site was started in 1995 and seems to have been most recently updated in 2009. These dates are clearly indicated on the species pages. It also appears to be best for animal species that still can be found alive today, as searches for mammoths and saber-toothed tigers produced nothing (but dodos had an entry). Though ADW has some limitations, it is otherwise a nice, easy-to-use database providing fairly in-depth coverage of animals and their natural histories.

Although Animal Diversity Web can be used by younger students, it is probably most useful for high school students. As such, this database should be linked to on high school libraries’ computers and included in a list of science resources for students at public libraries.


Section Summary

Animals constitute a diverse kingdom of organisms. Although animals range in complexity from simple sea sponges to human beings, most members share certain features. Animals are eukaryotic, multicellular, heterotrophic organisms that ingest their food and usually develop into motile creatures with a fixed body plan. Most members of the animal kingdom have differentiated tissues of four main classes—nervous, muscular, connective, and epithelial—that are specialized to perform different functions. Most animals reproduce sexually, leading to a developmental sequence that is relatively similar across the animal kingdom.

Organisms in the animal kingdom are classified based on their body morphology and development. True animals are divided into those with radial versus bilateral symmetry. Animals with three germ layers, called triploblasts, are further characterized by the presence or absence of an internal body cavity called a coelom. Animals with a body cavity may be either coelomates or pseudocoelomates, depending on which tissue gives rise to the coelom. Coelomates are further divided into two groups called protostomes and deuterostomes, based on a number of developmental characteristics.


Watch the video: Animal Classification. Evolution. Biology. FuseSchool (August 2022).