Introduction to Animal Kingdom Invertebrates and Vertebrates
Introduction To Animals Vertebrate animal with a backbone. Invertebrate animal without a backbone; includes more than 95% of all animal species alive today.
Characterisitcs 1.) Multicellular Organization - adult human has about 50 trillion cells - no cell walls Specialization the differentiation of a cell for a particular function; such as cells designed for digestion or reproduction. Cell Junctions connections between cells that hold the cells together as a unit; this leads to the formation tissues.
2.) Heterotrophy Ingestion when an animal takes in organic material, usually in the form of other living things. 3.) Sexual Reproduction & Development - most animals reproduce sexually & some asexually. Zygote - the first cell of a new individual, which then undergoes repeated mitotic divisions.
Differentiation a process in which the cells of a multicellular individual become specialized during development. 4.) Movement - most animals move about their environment. - movement results from the interrelationship of two types of tissue found only in animals: Nervous tissue & Muscle tissue. Neurons cells of nervous tissue that conduct electrical signals throughout an animal s body.
Origin & Classification The first animals probably arose in the sea in the form of colonial protests. Colonial organisms may have exhibited basic cell specialization early in evolutionary history.
Body Structure Dorsal top Ventral bottom Anterior head Posterior tail(end)
Symmetry refers to consistent overall pattern of structure Radial Symmetry similar parts branch out in all directions from a central line. Cnidarians, such as sea anemones, jellyfishes and hydra are radially symmetrical. Bilateral Symmetry having two similar halves on either side of a central plane. bilaterally symmetrical animals tend to exhibit cephalization.
Cephalization the concentration of sensory and brain structures in the anterior end of the animal; a cephalized animal has a head. head precedes the rest of the body, sensing danger, prey or a potential mate! Germ layers a specific layer of cells in an embryo from which specific organ systems are derived. Cnidarians and Ctenophores have 2 germ layers All other animals have 3 germ layers. Body Cavities a fluid-filled space that forms between the digestive tract and the outer wall of the body during development. some animals, such as flatworms lack a body cavity
Animal Diversity Invertebrates no backbone; 10 phyla. Phylum Porifera (sponges) Phylum Cnidaria (hydras, jellyfish, corals, sea anemones) Phylum Ctenophora (comb jellies) Phylum Platyhelminthes (flat worms) Phylum Rotifera (wormlike or spherical animals) Phylum Nematoda (tiny, parasitic, unsegmented worms; pin worms, hook worms, round worms) Phylum Mollusca (clams, snails, octopuses, squids, mussels, slugs) Phylum Annelida (sandworms, earthworms, leeches) Phylum Arthropoda (crabs, shrimp, lobsters, spiders, insects, centipedes, millipedes, sowbugs) Phylum Echinodermata (sea lilies, sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers)
Phylum Chordata Phylum Chordata organisms with a notochord, dorsal nerve cord pharyngeal pouches and postanal tail. Notochord a firm, flexible rod of tissue located in the dorsal part of the body. - found in all chordates at some stage of development. - develops into backbone. Dorsal Nerve Cord a neural tube dorsal to the notochord. develops into the brain and spinal cord in most vertebrates.pharyngeal Pouches small outpockets of the anterior part of the digestive tract. Pharyngeal Pouches small outpockets of the anterior part of the digestive tract. develops into gills in fish. Postanal Tail consists of muscle tissue and lies behind the posterior opening of the digestive tract. Subphylum Vertebrata animals whose notochord is replaced by a spinal column composed of vertebrae that protect the dorsal nerve cord. recognizable head containing brain. about 45,000 species.
COMPARISON OF INVERTEBRATES AND VERTEBRATES
Invertebrate Characteristics 1.) Radial or Bilateral symmetry 2.) Segmentation division of a body into a series of repeating similar units. 3.) Support of the Body supported by the pressure of a fluid-filled body cavity, protein fibers (spongin), exoskeleton. Exoskeleton a rigid outer covering that protects the soft tissues of many animals, including arthropods. must be shed and replaced as the animal grows. 4.) Respiratory & Circulatory Systems Gas Exchange carbon dioxide in the blood is exchanged with oxygen. Gills organs specialized for gas exchange in water. Circulatory System moves blood or a similar fluid through the body to transport oxygen and nutrients to cells and carbon dioxide and wastes away from cells. Open Circulatory System bloodlike circulatory fluid is pumped from vessels in the body into the body cavity, and then is returned to the vessels. found in Arthropods & some Mollusks. Closed Circulatory System blood circulates through the body in tubular vessels. The exchange of gases, nutrients and wastes occurs between body cells and very small blood vessels that lie near each cell.
5.) Digestive & Excretory Systems Gut a digestive tract running through the body of most invertebrates. 6.) Nervous System Large degree of diversity. No neurons in sponges to complex decision-making behavior in the octopus. 7.) Reproduction & Development Asexual & Sexual reproduction in some species. Hermaphrodite an organism that produces both male and female gametes, allowing a single individual to function as both a male and a female. Indirect Development animals that have a larval stage during their development. Larva a free-living, immature form of an organism. Direct Development an organism is born or hatched with the same appearance and way of life it will have as an adult; no larval stage occurs.
Vertebrate Characteristics 1.) Support of the Body Endoskeleton an internal skeleton that can support a large, heavy body. Vertebrae repeating bony units of the backbone. 2.) Body Coverings Integument outer covering of an animal (the skin). 3.) Respiratory & Circulatory Systems Lungs organs for gas exchange composed of moist, membranous surfaces deep inside the animal s body. evolved in terrestrial vertebrates Closed circulatory system
4.) Digestive & Excretory Systems Kidneys organs that filter wastes from the blood while regulating water levels in the body of most vertebrates. 5.) Nervous System Highly organized brains. Control of specific functions occurs in specific centers in the brain. 6.) Reproduction & Development Sperm & Egg Zygote
Fertilization & Development in Animals Gametes sperm & egg Fertilization the egg and sperm fuse together creating a zygote. Cleavage & Blastula Formation Cleavage divisions of the zygote immediately following fertilization. Blastula a hollow ball of cells formed when a zygote undergoes repeated cycles of cell division. Blastocoel the central cavity of a blastula.
Gastrulation an area of the blastula begins to collapse inward. Blastopore infolded region of the blastula. Gastrulation the inward collapsing of the blastula that forms a blastopore. Gastrula multilayered embryo. Archenteron a deep cavity that develops in the cup-shaped embryo (gastrula). functions as the gut. Ectoderm outer germ layer of the gastrula. forms the skin, hair, nails and nervous system. Endoderm inner germ layer Mesoderm a third layer that forms between the endoderm and the ectoderm. forms the skeleton, innerlayer of skin, circulatory system and lining of body Endoderm cavity.
Patterns of Development Coelom body cavity completely lined by mesoderms. Blastopore Fate & Cleavage Two different patterns of development in animals that have a coelom. Protostomes organisms whose blastopore develops into a mouth, and anotheropening eventually arises and develops into anus seen in the embryos of mollusks, arthropods and annelids. Spiral Cleavage where the cells divide in a spiral arrangement. seen in many protostomes. Deuterostomes organisms whose blastopore develops into an anus, and a second opening in the embryo becomes the mouth. seen in the embryos of echinoderms and chordates. Radial Cleavage where the cell divisions are parallel to or at right angles to the axis from one pole of the blastula to the other.
Determinate Cleavage a process in which each cell develops into a specific part of the gastrula. seen in many protostomes. Indeterminate Cleavage a pattern of development in which the functional destiny of each cell is not determined early in the development of the embryo. seen in many deuterostomes. can result in identical twins when it occurs very early in human embryo development.
Coelom Formation Schizocoely (split body cavity) the method of coelom formation in protostomes that Involves splitting the embryonic mesoderm into two layers. Enterocoely (gut body cavity) - the process of mesoderm formation in deuterostomes in which the coelom forms in folded mesoderm.
Types of Body Cavities Acoelomates an animal with no coelom, or body cavity. seen in flatworms Pseudocoelom in animals, a cavity between the mesoderm and the endoderm. means false body cavity Pseudocoelomates animals with a pseudocoelom. Coelomates animals with a true coelom. the mesoderm lines the body cavity and surrounds and supports the endodermic gut. Mollusks, Annelids, Arthropods, Chordates & Echinoderms.