What is Zoology PowerPoint Presentation

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Kingdom Animalia Zoology: The Study of Animals

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6 Characteristics of the Animals 1. Animals are multicellular ……………….. Except for sponges, animal cells are arranged into tissues (a tissue is a group of cells alike in structure and function… such as muscle tissue or brain tissue). Tissues are necessary to produce organs and organ systems.

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2. Animals are heterotrophs Heterotrophs consume their organic food. Heterotrophs are not capable of making their own foods.

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3. Animals are diploid The dominant generation in the life cycle is the diploid generation. Their gametes are heterogametes (different sizes); eggs are larger than sperm. Gametes are produced by meiosis. A typical animal life cycle is shown below.

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4. Animals are motile Heterotrophy often requires motility to capture prey. Animals have motility during at least some part of their life cycle.

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5. Animals have a period of embryonic development During embryonic development, cells become specialized and form two or three layers of tissues.

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6. Animal cells lack cell walls Therefore a skeleton is necessary to support the tissues of large animals.

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Classification of the Kingdom Animalia Protozoans Asymmetry Radial Symmetry Protostomes Deuterostomes * No Body Plan Body Radiates from a Central Point Mouth forms at the Blastopore Anus forms at the Blastopore Evolutionary Trend Simple Complex An increase in “Cell Specialization” and “Division of Labor” 1. Phylum Porifera (Sponges) 2. Phylum Cnidaria (Jellyfish, Sea Anemone) Bilateral Symmetry Body Plan Includes Anterior and Posterior Ends Dorsal and Ventral Surfaces “Right” and “Left” sides are mirror images Radial Symmetry Bilateral Symmetry Coelomates Pseudocoelomates Coelomates Coelomates Acoelomates 3. Phylum Platyhelminthes (Flatworms) 4. Phylum Nematoda (Roundworms) 8. Phylum Arthropoda (Insects, Spiders) 7. Phylum Mollusca (Snails, Clams) 6. Phylum Annelida (Segmented Worms) 9. Phylum Echinodermata (Starfish, Sea Urchins) 10. Phylum Chordata *Class Ichthyes *Class Amphibia *Class Reptilia *Class Aves *Class Mammalia Phyla 1-9 are Invertebrates “Animals without backbones” Coelom: body cavity found between two layers of mesoderm. 5. Phylum Rotifera (Rotifers)

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The key to the success of the Animals is their Diversity Diversity is defined as the presence of a wide range of variation. The Diversity of the Animals originates from the variations that occur in their: 1. Tissue Complexity 2. Body Symmetry 3. Cephalization 4. GastroVascular Cavity (GVC) 5. Coelom 6. Segmentation, and 7. Protostomes and Deuterostomes.

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1. Tissue Complexity Most animals, collectively called the eumetozoa, have closely functioning tissues. Some organisms are diploblastic, have only two cell layers… hydra and jellyfish. Some organisms are triploblastic and three cell layers. The three “germ layers” are the ectoderm, mesoderm and endoderm. Another group of animals, the parazoa (sponges) are not organized into true tissues and lack organs.

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Embryonic Germ Layers The three layers of tissues that become established during early embryonic development are called germ layers. They give rise to the body tissues. These layers are ectoderm, mesoderm, and endoderm.

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Embryonic Germ Layers

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Embryonic Germ Layers The ectoderm forms from the outer layer of cells. It gives rise to the skin and nervous system. The endoderm made of cells that form the tube-like structure in the gastrula. These cells will form the lining of the gut and the major organs are derived from it. Mesoderm forms between the ectoderm and endoderm. It becomes the muscles, connective tissues, skeleton, kidneys, circulatory and reproductive organs.

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2. Body Symmetry Body Shapes

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Asymmetry Asymmetrical animals have no pattern of symmetry. The simplest animals (sponges) are asymmetrical.

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Radial Symmetry The body parts of a radially symmetrical animal are arranged around a central axis so that each part extends from the center. Animals that exhibit radial symmetry tend to be sessile (immobile). Radial symmetry allows them to reach out in all directions.

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Bilateral Symmetry Only one cut along the longitudinal axis will produce identical halves of a bilaterally symmetrical animal. Bilateral symmetry is best for motile animals. Body Plan Includes Anterior and Posterior Ends Dorsal and Ventral Surfaces “Right” and “Left” sides are mirror images Longitudinal Axis

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Evolution of Symmetry The evolutionary sequence progressed from asymmetrical animals to radial and then to bilaterally symmetrical animals.

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Evolutionary Changes in the Animal Body 1. Body Cavities 2. Cephalization 3. Segmentation

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3. Cephalization The term “Cephalo” means “head”. In animals with bilateral symmetry, there is a greater increase in the nerve tissue concentrated in the anterior end (the head) as animals increase in complexity. For example, brains have formed with accessory organs for seeing, hearing, tasting, etc.

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4. Gastrovascular Cavity (GVC) GastroVascular Cavities (GVC) are areas where food is digested. If they have only one opening, the processing is limited. Two openings designate a digestive tract allowing food to be digested more thoroughly. Gastrovascularcavity

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5. The Coelom: Body Cavity The body cavity is a space that separates the gut and internal organs from the rest of the body. It isolates the internal organs from body-wall movements. It also bathes the internal organs in a liquid through which nutrients and wastes can diffuse.

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Arrangement of Ectoderm, Mesoderm, and Endoderm An acoelomate animal does not have a body cavity. Digestive cavity

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A pseudocoelomate animal has a body cavity (called a pseudocoelom) located between endoderm and mesoderm. pseudocoelom Digestive cavity

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The body cavity of a coelomate animal (called a coelom) is located within the mesoderm. The mesentery holds the gut in place. Digestive cavity Coelom Mesoderm

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6. Segmentation Many animals have segmented body parts. In some cases the parts repeat over and over again, as with earthworms. In other animals, the segments are modified, such as with insects… they essentially have 3 segments…. the head, thorax and abdomen. An Earthworm segmentation

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7. Body Plans: Protostomes and Deuterostomes

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Embryonic Development During early development, the fertilized egg divides, or cleavages, to produce a solid ball of cells. Then, cell migration results in a hollow ball called a blastula.

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Embryonic Development Some cells of the blastula migrate inward producing a gastrula. The opening is the blastopore. The internal cavity is called the archenteron.

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Embryonic Development The Gastrula will become the gut (digestive tract) of the mature animal. In species that have a separate mouth and anus, the tube will eventually extend through the length of the embryo and fuse with the opposite side. One opening will become the mouth, the other will become the anus.

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( Blastopore becomes the anus) ( Blastopore becomes the mouth) Blastopore Blastopore

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3 Major Differences between Protostomes and Deuterostomes

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6 Major Trends in Evolution 1. multicellularity 2. development of tissues, first none (sponges), then 2 (cnidarians), then 3 3. development of symmetry, first none (sponges), then radial (cnidarians), then bilateral 4. development of a gut, first none (sponges), then sac-like (cnidarians, flatworms), then complete 5. development of a body cavity, first none (flatworms), then a pseudocoelom (roundworms), then a coelom 6. development of segmentation; segmentation evolved in protostomes (annelids and arthropods) independently of that which evolved in deuterostomes.

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Summary of Evolutionary Trends Symmetry Asymmetry Radial Bilateral Gut No Gut Saclike Complete Coelom Acoelomate Pseudocoelomate Coelomate Embryonic Germ Layers None 2, (tissues, no organs) 3, (tissues and organs)

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Evolutionary Trends (sponges) (jellyfish, hydra) (flatworms) (roundworms) (rotifers) (clams, snails) (earthworms) (insects, spiders) (starfish, sea urchins) (common name)

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Classification of the Kingdom Animalia Protozoans Asymmetry Radial Symmetry Protostomes Deuterostomes * No Body Plan Body Radiates from a Central Point Mouth forms at the Blastopore Anus forms at the Blastopore Evolutionary Trend Simple Complex An increase in “Cell Specialization” and “Division of Labor” 1. Phylum Porifera (Sponges) 2. Phylum Cnidaria (Jellyfish, Sea Anemone) Bilateral Symmetry Body Plan Includes Anterior and Posterior Ends Dorsal and Ventral Surfaces “Right” and “Left” sides are mirror images Radial Symmetry Bilateral Symmetry Coelomates Pseudocoelomates Coelomates Coelomates Acoelomates 3. Phylum Platyhelminthes (Flatworms) 4. Phylum Nematoda (Roundworms) 8. Phylum Arthropoda (Insects, Spiders) 7. Phylum Mollusca (Snails, Clams) 6. Phylum Annelida (Segmented Worms) 9. Phylum Echinodermata (Starfish, Sea Urchins) 10. Phylum Chordata *Class Ichthyes *Class Amphibia *Class Reptilia *Class Aves *Class Mammalia Phyla 1-9 are Invertebrates “Animals without backbones” Coelom: body cavity found between two layers of mesoderm. 5. Phylum Rotifera (Rotifers)

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Kingdom Animalia Survey

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1. Phylum Porifera (Sponges)

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Phylum Porifera (Sponges) (exit for water) (digest and distribute food) (skeleton) Choanaocyte *** Sponges are Parazoans: they contain NO true tissues *** Sponges are filter feeders

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2. Phylum Cnidaria Jellyfish, Corals, and other Stingers

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General Characteristics Simple body plan-bag shaped organism Radially symmetrical organization Consists of a mouth and a sac-like cavity Lacks an anus The mouth is surrounded by a ring of tentacles The cavity in the center of the gut, called the gastrovascular cavity.

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Two Body Forms Polyps - attached to a surface - ex: sea anemones - mouth points up Medusae - free floating -ex: jellyfish -mouth points down

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The Tissue Layers Inner tissue layer (endoderm): gastrodermis Outer tissue layer (ectoderm): epidermis -contains cnidocysts, the stinging cells Middle layer (lacks a mesoderm): mesoglea (jelly-like substance)

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3. Phylum Platyhelminthes (Flatworms) Platyhelminthes consists of three kinds of acoelomate flatworms. 1. Free-living Flatworms: such as planarians, which are carnivorous scavengers. 2. Flukes: are internal, or external, parasites that suck tissue fluids or blood. 3. Tapeworms: internal parasites that live in the intestinal tracts of vertebrates.

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Planaria

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Tapeworm Scolex (head) Young Proglottids Old Proglottids ** tapeworms appear to be segmented, but they are not true “segmented” worms

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4. Phylum Nematoda (Roundworms) • Found in fresh water, marine, moist soil, tissues of plants, and tissues and body fluids of animals • A complete digestive tract is present and nutrients are transported through the body in the pseudocoelomic fluid. • Free-living forms are important in decomposition • Animal parasitic forms can be hazardous to health. (Trichinella spiralis in humans via undercooked infected pork)

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Nematode

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5. Phylum Rotifera (Rotifers) Rotifers are small, mainly freshwater organisms, although some are marine and others are found in damp soil. Complete digestive system is present. Rotifer refers to the crown of cilia that draws a vortex of water into the mouth.

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Rotifer

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6. Phylum Mollusca (snails, bivalves (such as clams….have a shell which has two parts), octopuses and squids) In Squids, the shell is reduced and is internal. In octopuses, the shell is entirely absent. Octopuses have a highly developed nervous system with a large, complex brain.

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Snails

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7. Phylum Annelid (Segmented Worms: includes leeches, earthworms and polychaetes) Leeches are freshwater but some are terrestrial in moist vegetation. Many are carnivorous and feed on small invertebrates, while some attach temporarily to animals to feed on blood. They have 2 suckers, one at each end. Earthworms ingest soil, extract nutrients in the digestive system and deposit undigested material (mixed with mucus from the digestive tract) as casts through the anus. Important to farmers as they till the soil and castings improve soil texture. Polychaetae drift and swim in the plankton, some crawl along the sea floor, and many live in tubes they construct by mixing sand and shell bits with mucus. Tube-dwellers include the fanworms that feed by trapping suspended food particles in their feathery filters which are extended from the tubes.

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Phylum Annelid (Segmented Worms: includes leeches, earthworms and polychaetes) Fanworm Polychaete Worm

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8. Phylum Arthropoda (spiders, insects, crustaceans, and various related organisms) Arthropods have two kinds of life cycles…(1) complete metamorphosis, (2) incomplete metamorphosis. Arthropods have: * jointed appendages, * a well-developed nervous system, * specialized body segments, and * an exoskeleton made of chiton.

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The specialized body segments are the: Head, Thorax and Abdomen

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Incomplete Metamorphosis (immature forms are often called nymphs) Nymphs resemble the adult in form except for being smaller and lacking fully developed wings and sexual organs. Life Cycle: Egg nymph adult

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Complete metamorphosis Immature forms are called larvae (larva, singular). The pupal stage is a transition stage, when the larva is transformed to the adult. Pupa molts to the adult form. Life Cycle: Egg --> larva --> pupa --> adult

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9. Phylum Echinodermata (sea stars (starfish), sea urchins and sand dollars) Echinoderms are Coelomates Deuterostomes Echinoderms have complete digestive systems Although some adults exhibit radial symmetry, some features are bilateral, as are the body shapes of their larvae.

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10. Phylum Chordata The Phylum Chordata consists of animals that exhibit the following four features. In many cases, these features are temporary, appearing only during embryonic development.

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1. A Notochord A notochord provides support for the body. It is a flexible cord located on the dorsal surface. In most cases, the notochord is replaced by bone during development. Notochord

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2. A Dorsal Hollow Nerve Cord A dorsal hollow nerve cord forms the basis of the nervous system. In some chordates, the nerve cord becomes the brain and spinal cord.

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3. Pharyngeal Gill Slits Pharyngeal Gill Slits provides channels across the pharynx to the outside of the body. In some chordates, the slits become gills for oxygen exchange, or for filter feeding, while in others, the slits disappear during embryonic development.

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4. A Muscular Tail A muscular tail extends beyond the digestive system. In many chordates, such as humans, the tail is lost during embryonic development.

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There are Two Groups of Chordates 1. Invertebrate Chordates: includes lancelets and tunicates. 2. Vertebrate Chordates: includes sharks, fish, amphibians, reptiles, birds and mammals. Vertebrate Chordates are characteristics by a series of bones, the vertebrae, that enclose the spinal cord.