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Kingdom Animalia

Navy Marine Mammals Navy Marine Mammals US Navy Marine Mammal Program – This Navy facility researches and trains sea mammals to perform underwater tasks that help the military. They include – Dolphins, California sea lions, whales and other sea mammals. Tasks include, detecting suspicious objects, locating lost objects etc. Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Let's start exploring the amazing facts of animals.

Learning Objectives

After completing the topic, the student will be able to:

  • List the general characteristics of animals and explore how animals evolved.
  • Identify on which fundamental basis, animals are classified.
  • Categorize the major branch points in the phylogeny of animal evolution.
  • Understand and systematize the basic steps involved in animal development and classify ten major phyla of animal kingdom.
  • Recognize the characters that distinguish humans from other hominoids .
  • Co – relate the concepts – animal cell development and stem – cell research.
  • Explore why Homo sapiens are highly developed organisms than any other organisms.
  • Compare and contrast the features of vertebrates and invertebrates.
An underwater glimpse of animal diversity on and around a coral reef. An underwater glimpse of animal diversity on and around a coral reef Kingdom Animalia is one of four kingdoms in the Domain Eukarya. It is distinct from the other three kingdoms, Plantae, Fungi, and Protista, in several ways.
Kingdom Animalia

Animals are multicellular, heterotrophic (an organism that cannot prepare their own food) eukaryotes with tissues that develop from embryonic layers. Biologists have identified 1.3 million living species of animals. Estimates of the total number of animal species run far higher, from 10 to 20 million to as many as 100 to 200 million.

There are some basic features that are found in all of the members of the kingdom Animalia. In general, animals are all motile, heterotrophic, and multicellular. Animals are ingestive heterotrophs (they ingest nutrients). Unlike plants, who store their food as starch, animals store their food as glycogen.

Animal cells lack cell walls that provide structural support for plants and fungi. The multicellular bodies of animals are held together by extracellular structural proteins, especially collagen.

Development of an organism Development of an organism A zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers– an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.
Animal cells

The bodies of most animals (all except sponges) are made up of cells organized into tissues, each tissue specialized to some degree to perform specific functions. Animals have other unique types of intercellular junctions, including tight junctions, desmosomes, and gap junctions, which hold tissues together. These junctions are also composed of structural proteins.

Animals have muscle tissue and nervous tissue. These tissues can range from being indistinct to being highly complex. Most animals reproduce sexually, with the diploid stage usually dominating the life cycle. In most species, a small flagellated sperm fertilizes a larger, non-motile egg. The zygote undergoes cleavage, a succession of mitotic cell divisions, leading to the formation of a multicellular, hollow ball of cells called the blastula. During gastrulation, part of the embryo folds inward, forming layers of embryonic tissues that will develop into adult body parts. The resulting development stage is called a gastrula.

Some animals develop directly through transient stages into adults, but others have a distinct larval stage or stages. A larva is a sexually immature stage that is morphologically distinct from the adult, usually eats different foods, and may live in a different habitat from the adult. Animal larvae eventually undergo metamorphosis, transforming the animal into an adult.

Animals share a unique homeobox-containing (A homeobox is a DNA sequence found within genes that are involved in the regulation of patterns of anatomical development (morphogenesis) in animals, fungi and plants) family of genes known as Hox genes. All eukaryotes have genes that regulate the expression of other genes. Many of these regulatory genes contain common modules of DNA sequences called homeoboxes. All animals share the unique family of Hox genes, suggesting that this gene family arose in the eukaryotic lineage that gave rise to animals. Hox genes play important roles in the development of animal embryos, regulating the expression of dozens or hundreds of other genes. Hox genes control cell division and differentiation, producing different morphological features of animals.

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