Which Of The Following Is Not An Important Feature In Distinguishing Animals From Each Other?

Introduction to Beast Diversity

Features of the Animal Kingdom

OpenStaxCollege

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Learning Objectives

Past the stop of this section, you volition be able to:

• List the features that distinguish the kingdom Animalia from other kingdoms
• Explain the processes of animal reproduction and embryonic development
• Describe the roles that Hox genes play in evolution

Fifty-fifty though members of the brute kingdom are incredibly various, virtually animals share certain features that distinguish them from organisms in other kingdoms. All animals are eukaryotic, multicellular organisms, and near all animals accept a circuitous tissue structure with differentiated and specialized tissues. Nearly animals are motile, at least during sure life stages. All animals require a source of food and are therefore heterotrophic, ingesting other living or expressionless organisms; this feature distinguishes them from autotrophic organisms, such as most plants, which synthesize their own nutrients through photosynthesis. As heterotrophs, animals may be carnivores, herbivores, omnivores, or parasites ([link]ab). Near animals reproduce sexually, and the offspring laissez passer through a serial of developmental stages that institute a determined and fixed body plan. The body programme refers to the morphology of an animal, adamant by developmental cues.

All animals are heterotrophs that derive energy from food. The (a) black bear is an omnivore, eating both plants and animals. The (b) heartworm Dirofilaria immitis is a parasite that derives free energy from its hosts. It spends its larval stage in mosquitoes and its adult stage infesting the heart of dogs and other mammals, every bit shown here. (credit a: modification of work by USDA Forest Service; credit b: modification of piece of work past Clyde Robinson)

Complex Tissue Structure

As multicellular organisms, animals differ from plants and fungi because their cells don't take cell walls, their cells may exist embedded in an extracellular matrix (such every bit bone, peel, or connective tissue), and their cells have unique structures for intercellular communication (such as gap junctions). In addition, animals possess unique tissues, absent-minded in fungi and plants, which let coordination (nerve tissue) of motility (muscle tissue). Animals are also characterized by specialized connective tissues that provide structural support for cells and organs. This connective tissue constitutes the extracellular surroundings of cells and is fabricated upwards of organic and inorganic materials. In vertebrates, bone tissue is a type of connective tissue that supports the entire body structure. The complex bodies and activities of vertebrates need such supportive tissues. Epithelial tissues encompass, line, protect, and secrete. Epithelial tissues include the epidermis of the integument, the lining of the digestive tract and trachea, and brand up the ducts of the liver and glands of advanced animals.

The animal kingdom is divided into Parazoa (sponges) and Eumetazoa (all other animals). As very uncomplicated animals, the organisms in group Parazoa ("beside beast") do non contain true specialized tissues; although they practice possess specialized cells that perform different functions, those cells are not organized into tissues. These organisms are considered animals since they lack the ability to make their own food. Animals with true tissues are in the group Eumetazoa ("truthful animals"). When we think of animals, we normally retrieve of Eumetazoans, since almost animals fall into this category.

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

Link to Learning

Lookout man a presentation by biologist Due east.O. Wilson on the importance of diversity.

Brute Reproduction and Development

Most animals are diploid organisms, meaning that their body (somatic) cells are diploid and haploid reproductive (gamete) cells are produced through meiosis. Some exceptions be: For example, in bees, wasps, and ants, the male is haploid considering it develops from unfertilized eggs. Most animals undergo sexual reproduction: This fact distinguishes animals from fungi, protists, and bacteria, where asexual reproduction is common or sectional. Notwithstanding, a few groups, such as cnidarians, flatworm, and roundworms, undergo asexual reproduction, although nearly all of those animals also have a sexual phase to their life cycle.

Processes of Animal Reproduction and Embryonic Development

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

Some animal species—including body of water stars and ocean anemones, besides equally some insects, reptiles, and fish—are capable of asexual reproduction. The virtually common forms of asexual reproduction for stationary aquatic animals include budding and fragmentation, where part of a parent individual can separate and grow into a new individual. In contrast, a form of asexual reproduction found in sure insects and vertebrates is called parthenogenesis (or "virgin starting time"), where unfertilized eggs tin can develop into new male person offspring. This type of parthenogenesis is chosen haplodiploidy. These types of asexual reproduction produce genetically identical offspring, which is disadvantageous from the perspective of evolutionary adaptability because of the potential buildup of deleterious mutations. However, for animals that are express in their chapters to attract mates, asexual reproduction tin can ensure genetic propagation.

Subsequently fertilization, a serial of developmental stages occur during which primary germ layers are established and reorganize to form an embryo. During this process, fauna tissues begin to specialize and organize into organs and organ systems, determining their future morphology and physiology. Some animals, such as grasshoppers, undergo incomplete metamorphosis, in which the young resemble the developed. Other animals, such as some insects, undergo consummate metamorphosis where individuals enter i or more larval stages that may in differ in construction and office from the adult ([link]). For the latter, the young and the adult may have 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 aforementioned for most members of the animal kingdom.

(a) The grasshopper undergoes incomplete metamorphosis. (b) The butterfly undergoes consummate metamorphosis. (credit: Southward.E. Snodgrass, USDA)

The process of animal development begins with the cleavage, or serial of mitotic cell divisions, of the zygote ([link]). 3 cell divisions transform the unmarried-celled zygote into an 8-celled construction. After farther cell sectionalisation and rearrangement of existing cells, a vi–32-celled hollow construction called a blastula is formed. Next, the blastula undergoes further prison cell division and cellular rearrangement during a process chosen gastrulation. This leads to the formation of the side by side developmental stage, the gastrula, in which the future digestive crenel is formed. Different cell layers (called germ layers) are formed during gastrulation. These germ layers are programmed to develop into sure tissue types, organs, and organ systems during a process called organogenesis.

During embryonic development, the zygote undergoes a serial of mitotic prison cell divisions, or cleavages, to form an viii-prison cell stage, and then a hollow blastula. During a procedure chosen gastrulation, the blastula folds in to form a cavity in the gastrula.

Link to Learning

Watch the post-obit video to see how human embryonic evolution (later on the blastula and gastrula stages of evolution) reflects evolution.

The Part of Homeobox (Hox) Genes in Animal Development

Since the early on xix^thursday century, scientists take observed that many animals, from the very unproblematic to the complex, shared similar embryonic morphology and development. Surprisingly, a human being embryo and a frog embryo, at a certain phase of embryonic evolution, look remarkably akin. For a long fourth dimension, scientists did not understand why then many animal species looked similar during embryonic development but were very different as adults. They wondered what dictated the developmental direction that a fly, mouse, frog, or human embryo would take. Near the finish of the 20^th century, a particular class of genes was discovered that had this very task. These genes that determine animate being structure are chosen "homeotic genes," and they contain DNA sequences called homeoboxes. The animal genes containing homeobox sequences are specifically referred to every bit Hox genes. This family of genes is responsible for determining the general body plan, such as the number of torso segments of an animal, the number and placement of appendages, and animate being head-tail directionality. The first Hox genes to be sequenced were those from the fruit wing (Drosophila melanogaster). A unmarried Hox mutation in the fruit fly can result in an extra pair of wings or even appendages growing from the "wrong" body part.

While there are a great many genes that play roles in the morphological development of an beast, what makes Hox genes so powerful is that they serve as master control genes that can plow on or off big 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, that is, the genetic sequences of Hox genes and their positions on chromosomes are remarkably similar across near animals considering of their presence in a common ancestor, from worms to flies, mice, and humans ([link]). Ane of the contributions to increased brute trunk complexity is that Hox genes have undergone at least two duplication events during animal evolution, with the additional genes allowing for more complex body types to evolve.

Art Connection

Hox genes are highly conserved genes encoding transcription factors that decide the grade of embryonic development in animals. In vertebrates, the genes have been duplicated into iv 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 betwixt Hox genes in mice and humans. Notation how Hox gene expression, as indicated with orange, pink, blueish and dark-green shading, occurs in the aforementioned torso segments in both the mouse and the human.

If a Hox 13 gene in a mouse was replaced with a Hox one gene, how might this alter animal evolution?

<!–<para>The animal might develop two heads and no tail.–>

Section Summary

Animals plant an incredibly diverse kingdom of organisms. Although animals range in complexity from elementary sea sponges to human being beings, most members of the animal kingdom share sure features. Animals are eukaryotic, multicellular, heterotrophic organisms that ingest their food and usually develop into motile creatures with a stock-still trunk programme. A major feature unique to the brute kingdom is the presence of differentiated tissues, such as nerve, muscle, and connective tissues, which are specialized to perform specific functions. Most animals undergo sexual reproduction, leading to a series of developmental embryonic stages that are relatively similar across the creature kingdom. A class of transcriptional control genes called Hox genes directs the organization of the major animal body plans, and these genes are strongly homologous beyond the brute kingdom.

Art Connections

[link] If a Hox 13 gene in a mouse was replaced with a Hox 1 gene, how might this alter animate being evolution?

[link] The animal might develop two heads and no tail.

Review Questions

Which of the following is not a feature mutual to most animals?

1. evolution into a stock-still trunk plan
2. asexual reproduction
3. specialized tissues
4. heterotrophic food sourcing

B

During embryonic evolution, unique cell layers develop and distinguish during a stage called ________.

1. the blastula stage
2. the germ layer stage
3. the gastrula stage
4. the organogenesis phase

C

Which of the following phenotypes would nigh likely be the upshot of a Hox gene mutation?

1. aberrant body length or height
2. two different eye colors
3. the contraction of a genetic illness
4. two fewer appendages than normal

D

Free Response

Why might the evolution of specialized tissues exist important for animal function and complexity?

The development of specialized tissues affords more complex animal anatomy and physiology because differentiated tissue types can perform unique functions and work together in tandem to permit the animal to perform more functions. For example, specialized muscle tissue allows directed and efficient movement, and specialized nervous tissue allows for multiple sensory modalities besides as the ability to respond to various sensory information; these functions are not necessarily bachelor to other non-beast organisms.

Draw and requite examples of how humans display all of the features mutual to the animal kingdom.

Humans are multicellular organisms. They also contain differentiated tissues, such every bit epithelial, muscle, and nervous tissue, as well every bit specialized organs and organ systems. As heterotrophs, humans cannot produce their ain nutrients and must obtain them by ingesting other organisms, such as plants, fungi, and animals. Humans undergo sexual reproduction, as well as the same embryonic developmental stages as other animals, which somewhen lead to a stock-still and motile body plan controlled in big part by Hox genes.

How accept Hox genes contributed to the diversity of beast torso plans?

Altered expression of homeotic genes can lead to major changes in the morphology of the private. Hox genes can affect the spatial arrangements of organs and body parts. If a Hox cistron was mutated or duplicated, it could bear upon where a leg might exist on a fruit wing or how far apart a person'south fingers are.

Glossary

blastula

16–32 cell stage of evolution of an brute embryo

torso plan

morphology or constant shape of an organism

cleavage

cell division of a fertilized egg (zygote) to form a multicellular embryo

gastrula

phase of animal development characterized by the formation of the digestive cavity

germ layer

collection of cells formed during embryogenesis that will give rise to futurity body tissues, more pronounced in vertebrate embryogenesis

Hox gene

(too, homeobox cistron) master control gene that can turn on or off large numbers of other genes during embryogenesis

organogenesis

formation of organs in animal embryogenesis

Source: http://pressbooks-dev.oer.hawaii.edu/biology/chapter/features-of-the-animal-kingdom/

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