What Are The Five Characteristics Of Animals

Characteristics of the Brute Kingdom

The beast kingdom is very various, only animals share many common characteristics, such as methods of development and reproduction.

Learning Objectives

Describe the methods used to allocate animals

Key Takeaways

Cardinal Points

• Animals vary in complexity and are classified based on anatomy, morphology, genetic makeup, and evolutionary history.
• All animals are eukaryotic, multicellular organisms, and most animals take complex tissue construction with differentiated and specialized tissue.
• Animals are heterotrophs; they must eat living or dead organisms since they cannot synthesize their own nutrient and can be carnivores, herbivores, omnivores, or parasites.
• Most animals are motile for at least some stages of their lives, and well-nigh animals reproduce sexually.

Key Terms

• body plan: an assemblage of morphological features shared among many members of a phylum-level grouping
• heterotroph: an organism that requires an external supply of free energy in the form of nutrient, every bit it cannot synthesize its own
• extant: nevertheless in existence; not extinct

Introduction: Features of the Brute Kingdom

Beast evolution began in the ocean over 600 1000000 years ago with tiny creatures that probably do non resemble any living organism today. Since so, animals have evolved into a highly-various kingdom. Although over 1 million extant (currently living) species of animals take been identified, scientists are continually discovering more species every bit they explore ecosystems around the world. The number of extant species is estimated to exist between iii and 30 million.

But what is an animate being? While we can easily identify dogs, birds, fish, spiders, and worms every bit animals, other organisms, such as corals and sponges, are not as easy to classify. Animals vary in complexity, from sea sponges to crickets to chimpanzees, and scientists are faced with the difficult chore of classifying them inside a unified system. They must identify traits that are common to all animals as well as traits that tin be used to distinguish among related groups of animals. The fauna nomenclature system characterizes animals based on their anatomy, morphology, evolutionary history, features of embryological development, and genetic makeup. This classification scheme is constantly developing equally new information about species arises. Understanding and classifying the bang-up diverseness of living species help us meliorate understand how to conserve the diversity of life on earth.

Even though members of the brute kingdom are incredibly diverse, most animals share certain features that distinguish them from organisms in other kingdoms. All animals are eukaryotic, multicellular organisms, and nearly all animals have a circuitous tissue construction with differentiated and specialized tissues. Most animals are motile, at least during certain life stages. All animals require a source of food and are, therefore, heterotrophic: ingesting other living or dead organisms. This feature distinguishes them from autotrophic organisms, such as virtually plants, which synthesize their own nutrients through photosynthesis. As heterotrophs, animals may be carnivores, herbivores, omnivores, or parasites. Most animals reproduce sexually with the offspring passing through a series of developmental stages that establish a fixed body plan. The trunk plan refers to the morphology of an animal, determined by developmental cues.

Heterotrophs: All animals are heterotrophs that derive energy from nutrient. The (a) blackness bear is an omnivore, eating both plants and animals. The (b) heartworm Dirofilaria immitis is a parasite that derives energy from its hosts. It spends its larval phase in mosquitoes and its adult stage infesting the heart of dogs and other mammals.

Complex Tissue Construction

Animals, besides Parazoa (sponges), are characterized past specialized tissues such every bit muscle, nervus, connective, and epithelial tissues.

Learning Objectives

List the various specialized tissue types constitute in animals and describe their functions

Key Takeaways

Key Points

• Animate being cells don't have jail cell walls; their cells may be embedded in an extracellular matrix and take unique structures for intercellular communication.
• Animals take nervus and muscle tissues, which provide coordination and movement; these are not present in plants and fungi.
• Complex creature bodies demand connective tissues made up of organic and inorganic materials that provide support and structure.
• Animals are besides characterized by epithelial tissues, like the epidermis, which function in secretion and protection.
• The animal kingdom is divided into Parazoa (sponges), which practise non contain true specialized tissues, and Eumetazoa (all other animals), which do contain true specialized tissues.

Key Terms

• Parazoa: a taxonomic subkingdom inside the kingdom Animalia; the sponges
• Eumetazoa: a taxonomic subkingdom, inside kingdom Animalia; all animals except the sponges
• epithelial tissue: one of the four basic types of beast tissue, which line the cavities and surfaces of structures throughout the body, and also course many glands

Complex Tissue Construction

As multicellular organisms, animals differ from plants and fungi because their cells don't accept cell walls; their cells may exist embedded in an extracellular matrix (such as os, skin, or connective tissue); and their cells have unique structures for intercellular communication (such equally gap junctions). In add-on, animals possess unique tissues, absent in fungi and plants, which allow coordination (nerve tissue) and movement (muscle tissue). Animals are also characterized by specialized connective tissues that provide structural back up for cells and organs. This connective tissue constitutes the extracellular environment of cells and is made upwardly of organic and inorganic materials. In vertebrates, bone tissue is a blazon of connective tissue that supports the entire body structure. The complex bodies and activities of vertebrates need such supportive tissues. Epithelial tissues cover, line, protect, and secrete; these tissues include the epidermis of the integument: the lining of the digestive tract and trachea. They likewise make up the ducts of the liver and glands of advanced animals.

The animate being kingdom is divided into Parazoa (sponges) and Eumetazoa (all other animals). As very uncomplicated animals, the organisms in grouping Parazoa ("beside animal") do not contain true specialized tissues. Although they practise possess specialized cells that perform different functions, those cells are not organized into tissues. These organisms are considered animals since they lack the power to make their ain food. Animals with true tissues are in the group Eumetazoa ("true animals"). When we think of animals, nosotros usually think of Eumetazoans, since most animals fall into this category.

Sponges: Sponges, such as those in the Caribbean Sea, are classified as Parazoans because they are very simple animals that do non contain truthful specialized tissues.

The unlike types of tissues in true animals are responsible for carrying out specific functions for the organism. This differentiation and specialization of tissues is role of what allows for such incredible animal multifariousness. For instance, the evolution of nerve tissues and muscle tissues has resulted in animals' unique ability to rapidly sense and respond to changes in their environs. This allows animals to survive in environments where they must compete with other species to run into their nutritional demands.

Animal Reproduction and Development

Most animals undergo sexual reproduction and have like forms of development dictated by Hox genes.

Learning Objectives

Explain the processes of animal reproduction and embryonic evolution

Key Takeaways

Cardinal Points

• Most animals reproduce through sexual reproduction, but some animals are capable of asexual reproduction through parthenogenesis, budding, or fragmentation.
• Following fertilization, an embryo is formed, and animal tissues organize into organ systems; some animals may also undergo incomplete or complete metamorphosis.
• Cleavage of the zygote leads to the formation of a blastula, which undergoes further jail cell sectionalisation and cellular rearrangement during a process called gastrulation, which leads to the formation of the gastrula.
• During gastrulation, the digestive cavity and germ layers are formed; these volition later develop into sure tissue types, organs, and organ systems during a procedure called organogenesis.
• Hox genes are responsible for determining the full general body programme, such every bit the number of body segments of an animal, the number and placement of appendages, and creature head-tail directionality.
• Hox genes, similar across virtually animals, can turn on or off other genes by coding transcription factors that command the expression of numerous other genes.

Key Terms

• metamorphosis: a change in the form and frequently habits of an animal after the embryonic phase during normal development
• Hox cistron: genes responsible for determining the general body program, such as the number of torso segments of an animal, the number and placement of appendages, and animal head-tail directionality
• blastula: a vi-32-celled hollow structure that is formed after a zygote undergoes jail cell segmentation

Fauna Reproduction and Evolution

Most animals are diploid organisms (their body, or somatic, cells are diploid) with haploid reproductive ( gamete ) cells produced through meiosis. The majority of animals undergo sexual reproduction. This fact distinguishes animals from fungi, protists, and bacteria where asexual reproduction is common or exclusive. However, a few groups, such as cnidarians, flatworms, and roundworms, undergo asexual reproduction, although nearly all of those animals also accept a sexual phase to their life cycle.

Processes of Creature Reproduction and Embryonic Evolution

During sexual reproduction, the haploid gametes of the male and female individuals of a species combine in a process called fertilization. Typically, the small, motile male person sperm fertilizes the much larger, sessile female person egg. This procedure produces a diploid fertilized egg called a zygote.

Some animal species (including sea stars and body of water anemones, as well as some insects, reptiles, and fish) are capable of asexual reproduction. The most common forms of asexual reproduction for stationary aquatic animals include budding and fragmentation where function of a parent individual can separate and abound into a new individual. In dissimilarity, a form of asexual reproduction found in certain insects and vertebrates is chosen parthenogenesis where unfertilized eggs tin can develop into new offspring. This blazon of parthenogenesis in insects is called haplodiploidy and results in male offspring. These types of asexual reproduction produce genetically identical offspring, which is disadvantageous from the perspective of evolutionary adjustability because of the potential buildup of deleterious mutations. Withal, for animals that are limited in their chapters to attract mates, asexual reproduction tin can ensure genetic propagation.

After fertilization, a series of developmental stages occur during which primary germ layers are established and reorganize to course an embryo. During this process, fauna tissues brainstorm to specialize and organize into organs and organ systems, determining their time to come morphology and physiology. Some animals, such as grasshoppers, undergo incomplete metamorphosis, in which the immature resemble the adult. Other animals, such as some insects, undergo complete metamorphosis where individuals enter one or more larval stages that may differ in construction and function from the adult. In complete metamorphosis, the young and the developed may take different diets, limiting contest for food between them. Regardless of whether a species undergoes consummate or incomplete metamorphosis, the series of developmental stages of the embryo remains largely the same for most members of the animal kingdom.

Incomplete and complete metamorphosis: (a) The grasshopper undergoes incomplete metamorphosis. (b) The butterfly undergoes complete metamorphosis.

The process of animal evolution begins with the cleavage, or series of mitotic prison cell divisions, of the zygote. Three cell divisions transform the single-celled zygote into an eight-celled structure. After farther cell sectionalisation and rearrangement of existing cells, a 6–32-celled hollow structure called a blastula is formed. Side by side, the blastula undergoes further prison cell division and cellular rearrangement during a process chosen gastrulation. This leads to the formation of the next developmental stage, the gastrula, in which the future digestive cavity is formed. Different prison cell layers (called germ layers) are formed during gastrulation. These germ layers are programed to develop into certain tissue types, organs, and organ systems during a process chosen organogenesis.

Embryonic development: During embryonic development, the zygote undergoes a series of mitotic jail cell divisions, or cleavages, to form an eight-cell stage, and then a hollow blastula. During a procedure called gastrulation, the blastula folds inward to form a crenel in the gastrula.

The Part of Homeobox (Hox) Genes in Fauna Development

Since the early on 19^th century, scientists have observed that many animals, from the very simple to the complex, shared similar embryonic morphology and development. Surprisingly, a man embryo and a frog embryo, at a sure stage of embryonic development, appear remarkably similar. For a long time, scientists did not empathise why so many fauna species looked similar during embryonic development, but were very dissimilar as adults. Near the end of the xx^th century, a particular class of genes that dictate developmental direction was discovered. These genes that determine animal structure are called "homeotic genes." They incorporate Dna sequences called homeoboxes, with specific sequences referred to as Hox genes. This family of genes is responsible for determining the general trunk programme: the number of trunk segments of an animal, the number and placement of appendages, and animal head-tail directionality. The first Hox genes to be sequenced were those from the fruit fly (Drosophila melanogaster). A single Hox mutation in the fruit fly tin outcome in an extra pair of wings or even appendages growing from the "wrong" body part.

In that location are many genes that play roles in the morphological development of an animal, but Hox genes are then powerful because they tin turn on or off large numbers of other genes. Hox genes practise this by coding transcription factors that control the expression of numerous other genes. Hox genes are homologous in the animal kingdom: the genetic sequences and their positions on chromosomes are remarkably similar across most animals (due east.g., worms, flies, mice, humans) because of their presence in a mutual ancestor. Hox genes accept undergone at least two duplication events during animal evolution: the additional genes allowed more complex body types to evolve.

Hox genes: Hox genes are highly-conserved genes encoding transcription factors that determine the course of embryonic development in animals. In vertebrates, the genes take been duplicated into 4 clusters: Hox-A, Hox-B, Hox-C, and Hox-D. Genes within these clusters are expressed in certain body segments at certain stages of development. Shown here is the homology between Hox genes in mice and humans. Note how Hox gene expression, as indicated with orangish, pink, blue, and green shading, occurs in the same body segments in both the mouse and the human.

Source: https://courses.lumenlearning.com/boundless-biology/chapter/features-of-the-animal-kingdom/

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