Kingdom Animalia: Taxonomy and Morphology (PDF)

DON HONORIO VENTURA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES SCIENCES DEPARTMENT KINGDOM ANIMALIA: TAXONOMY AND MORPHOLOGY AN INTRODUCTION TO ANIMAL PHYLA GENERAL ZOOLOGY ZOOLOGY 105 animal organization  ANIMAL GRADES OF ORGANIZATION UNICELLULAR ORGANI...

DON HONORIO VENTURA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES SCIENCES DEPARTMENT KINGDOM ANIMALIA: TAXONOMY AND MORPHOLOGY AN INTRODUCTION TO ANIMAL PHYLA GENERAL ZOOLOGY ZOOLOGY 105 animal organization  ANIMAL GRADES OF ORGANIZATION UNICELLULAR ORGANISMS: METAZOANS (MULTICELLULAR ANIMALS) Simplest eukaryotic organisms. Evolved greater complexity by Protoplasmic grade of organization. combining cells. Complete organisms performing all Specialized cells for specific functions. life functions within a single cell. Not capable of independent Show remarkable organization and existence. division of labor. Diversity achieved through varying subcellular structures. animal symmetry ANIMAL SYMMETRY Animal symmetry refers to the arrangement of body parts in relation to a central axis or plane. It provides a framework for understanding the anatomical structure and evolutionary relationships of different organisms. ANIMAL SYMMETRY The basic body plans of animals may be analyzed to illustrate evolutionary trends. The first consideration is body symmetry. It can be classified into three main types: asymmetry, radial, and bilateral symmetry.  ANIMAL SYMMETRY asymmetry bilateral radial symmetry symmetry ASYMMETRY Asymmetrical animals are those animals in which any plane passing through the central axis of the body does not divide into equal halves. No discernible pattern or symmetry. Often found in simple organisms like sponges (Phylum Porifera).  RADIAL SYMMETRY RADIATA applies to forms that can be divided into similar halves by more than two planes passing through the longitudinal axis. Body parts are arranged around a central axis. Can be divided into identical halves along any plane passing through the center. Common in sessile or slow-moving organisms.  RADIAL SYMMETRY RADIATA includes Phylum Cnidaria (jellyfishes, corals) Phylum Ctenophora (sea walnuts, comb jellies) that are primarily radial adults Phylum Echinodermata (sea stars, sea urchins) are secondarily radial as adults since their larvae are bilateral. BILATERAL SYMMETRY BILATERIA applies to animals that can be divided along a sagittal plane into two mirrored portions— right and left halves Body can be divided into two identical halves along a single plane (sagittal plane). Most animals, including humans, exhibit bilateral symmetry. Allows for specialization of body parts and efficient movement. planes of symmetry PLANES & AXES PLANES - flat surfaces AXES - imaginary lines Frontal plane - runs from anterior to posterior and separates the dorsal and ventral Transverse plane - runs from dorsal to ventral and separates the anterior and posterior Mid-sagittal - runs from anterior to posterior and separates right and left equally Parasagittal - runs from anterior to posterior and separates right and left unequally. Terms used in locating and identifying parts. Anterior - head region Posterior - tail region Dorsal - upper side or back Ventral - under side or front body cavities & germ layers BODY CAVITIES Body cavities are internal spaces, such as the gut cavity and other fluid- filled spaces. Cushioning and protection of organs. Hydrostatic skeleton for locomotion. Its presence varies among animals; some have none, while others have one or more. Sponges lack body cavities, including a gut cavity. DEVELOPMENT OF BODY CAVITIES Metazoans, develop from a zygote to a blastula stage. A typical spherical blastula is composed of a layer of cells surrounding a fluid-filled cavity, a blastocoel, has no external opening, so it could not serve as a gut. Zygote -> Blastula (with blastocoel) -> Gastrula (with gut cavity) Sponges may or may not have a gastrula stage.  DEVELOPMENT OF BODY CAVITIES Blastula: A hollow sphere of cells formed during early embryonic development. Gastrulation: The process of invagination (pushing inward) of one side of the blastula to form a depression. Gut Cavity: The depression becomes the gut cavity, also known as the gastrocoel or archenteron.  DEVELOPMENT OF BODY CAVITIES Blastopore: The external opening to the gut cavity, which typically becomes the adult mouth or anus. Germ Layers: Endoderm: The inner layer of cells that forms the lining of the gut. Ectoderm: The outer layer of cells surrounding the blastocoel.  DEVELOPMENT OF BODY CAVITIES The vast majority of multicellular animals proceed from a blastula to a gastrula, producing two germ layers. In one of many quirks of biological terminology, there is no term for organisms with only a single germ cell layer  DEVELOPMENT OF BODY CAVITIES DIPLOBLASTIC ANIMALS: Have two germ layers: ectoderm and endoderm. Examples: sea anemones, comb jellies. TRIPLOBLASTIC ANIMALS: Have three germ layers: ectoderm, mesoderm, and endoderm. Most animals are triploblastic.  DEVELOPMENT OF BODY CAVITIES MESODERM FORMATION: Arises from endoderm near the blastopore. Proliferates between the archenteron and outer body wall. Can also form from the central region of the archenteron wall. Cells have new positions and neighbors after gastrulation. Interactions among cells and germ layers generate the body plan. DIPLOBLASTIC (Gr. diploos, two-fold, blastos, germ) Diploblastic animals are those that have two germ layers during their embryonic development: ectoderm and endoderm. These two layers give rise to different tissues and organs in the adult animal. Examples: jellyfishes, sea anemones, and corals DIPLOBLASTIC These organisms have two tissue layers formed from the embryonic ectoderm and endoderm.The cell layers are interdependent. Non- cellular, gelatinous mesoglea is present in between ectoderm and endoderm. Coelom is absent. TRIPLOBLASTIC (L. tres, three, blastos, germ) The third layer, mesoderm (Gr. mesos, middle, deros, skin), eventually lies between the ectoderm and the endoderm. The mesoderm, gives rise to a variety of tissues and organs, including muscles, bones, and connective tissues. Majority are bilaterally symmetrical. TRIPLOBLASTIC Triploblastic animals are divided among deuterostomes and protostomes according to their particular developmental sequence. Examples: Flatworms, Nematodes, Annelids, Mollusks, Arthropods, Echinoderms, Chordates. FORMATION OF THE COELOM Coelom is a body cavity completely surrounded by mesoderm it forms during gastrulation when the blastocoel is filled with mesoderm. Coelom is formed: by splitting within the mesoderm (schizocoely) or by the out-pocketing of the gut (enterocoely). When coelom formation is complete, the body has three germ layers and two cavities. One cavity is the gut cavity and the other is the fluid-filled coelomic cavity. The coelom, surrounded by its mesodermal walls, has completely filled the blastocoel. DEUTEROSTOMES vs. PROTOSTOMES TRIPLOBLASTIC ORGANIZATION COELOMATE Coelomate animals have a body cavity called a coelom that is completely surrounded by mesoderm. This coelom provides a space for organs to develop and function independently. Examples: Annelids, Mollusks, Arthropods, Echinoderms, Chordates. TRIPLOBLASTIC ORGANIZATION ACOELOMATE Acoelomate animals lack a body cavity. Their organs are packed together in a solid mass Mesodermal cells completely fill the blastocoel, leaving a gut as the only body cavity. The region between the ectodermal epidermis and endodermal digestive tract is filled with a spongy mass of space- filling cells, the parenchyma. TRIPLOBLASTIC ORGANIZATION ACOELOMATE Parenchyma is derived from embryonic connective tissue and is important in assimilation and transport of food and in disposal of metabolic wastes. Examples: flatworms TRIPLOBLASTIC ORGANIZATION PSEUDOCOELOMATE Pseudocoelomate animals have a body cavity that is not completely lined by mesoderm. Mesodermal cells line the outer edge of the blastocoel, leaving two body cavities: a persistent blastocoel and a gut cavity. TRIPLOBLASTIC ORGANIZATION PSEUDOCOELOMATE The name pseudocoelom means false coelom in reference to mesoderm only partially surrounding the cavity, instead of completely surrounding it, as in a true coelom. Examples: nematodes  invertebrates vs. vertebrates INVERTEBRATES A broad collection of animal groups (they do not belong to a single subphylum like the vertebrates) all of which lack a backbone. Some (not all) of the animal groups that are invertebrates includes: Phylum Porifera, Phylum Cnidaria, Phylum Ctenophora, Phylum Platyhelminthes, Phylum Mollusca, Phylum Arthropoda, Phylum Annelida, Phylum Nematoda, Phylum Echinodermata VERTEBRATES Vertebrates are a subphylum of Phylum Chordata characterized by having a backbone that supports the body and protects the spinal cord. Vertebrates are also bilaterians and has body segments and endoskeleton (bony or cartilaginous). These animals also possess pharyngeal pouches, ventral heart, complete digestive system, closed blood system, and tail (or remnants). VERTEBRATES FIVE MAJOR CLASSES: PISCES (Fishes): Cold-blooded aquatic animals with gills for breathing and fins for swimming. AMPHIBIA: Cold-blooded animals that can live both on land and in water, often undergoing metamorphosis from a larval stage to an adult stage. REPTILIA: Cold-blooded animals with scaly skin and eggs that are laid on land. AVES (Birds): Warm-blooded animals with feathers, wings, and beaks. MAMMALIA: Warm-blooded animals that produce milk to feed their young. ANIMAL PHYLA CHORDATA Coelomates with notochord Hollow dorsal nerve tube Pharyngeal slits Post anal tail at some stage of life In vertebrates the notochord is replaced by the vertebral column at certain stage during development Ex: amphibians, reptiles, birds and mammals PORIFERA Body is asymmetrical Without distinct tissues & organs With cavity or cavities connected to exterior pores Skeletons of siliceous or calcareous types called spicules; mostly sessile Ex: sponges, vase sponges CNIDARIA Usually radially symmetrical, with sac-like body cavity, the gastrocoel No anus Tentacles armed with stinging cells called cnidocytes provided with needle like cnidocil With two germ layers the ectoderm and endoderm, and the mesoglea at the middle Ex: Jellyfish, hard and soft corals PLATYHELMINTHES Body dorso-ventrally flattened Hermaphroditic With mouth No anus Most members are parasitic Ex: planaria, tapeworms, blood fluke and liver fluke ECHINODERMATA Spiny-skinned animals Exclusively marine Mostly pentaradiate Deuterostomic-type of embryonic development Unique water vascular system Ex: Sea urchins, sea stars, sea cucumbers & brittle stars ARTHROPODA Most successful of all the animal groups With chitinous exoskeleton that periodically molts allow for growth With jointed appendages Compound eyes for vision Ex: Insects, crustaceans, spiders, crabs, scorpions, millipedes & centepedes ANNELIDA Metamerically segmented Presence of septa and bristle like chetae per segment With important animal parasites Ex: tubeworms, earthworms, leeches MOLLUSCA Soft muscular foot With visceral hump containing digestive organs and usually protected with shells Tongue-like radula and mantle cavity where gills are located for gas exchange. Ex: Clams, snails, oysters, squids & octopus NEMATODA Acoelomate Unsegmented and bilaterally symmetrical worms Narrow and pointed on both ends With elastic cuticle Longitudinal muscles present but no circular muscles Contains many important parasites Ex: Ascaris, Filarial worms, pinworms and hookworms  DON HONORIO VENTURA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES SCIENCES DEPARTMENT THANK YOU! GENERAL ZOOLOGY ZOOLOGY 105