COMPARING INVERTEBRATES Chapter 29 Taxonomy The system we

COMPARING INVERTEBRATES Chapter 29

Taxonomy • The system we use today to name and classify • all organisms was developed by Carl Linnaeus. It is known as the system of binomial nomenclature because every organism has a two part name. – Ex: Pantera leo – Ex: Homo sapiens • In addition, Linneaeus classified every organism into a hierarchy of taxa, or levels of organization.

Taxonomy--Classification • Kingdom • Philip • Phylum • Came • Class • Over • Order • For • Family • Great • Genus • Spaghetti • Species

Example Classification • Domain • Eukarya • Kingdom • Animalia • Phylum • Chordata • Class • Mammalia • Order • Primate • Family • Hominid • Genus • Homo • Species • sapiens

Taxonomy • All life can be organized into three domains: Bacteria, Archaea, and Eukarya.

Bacteria • Single celled • • • prokaryotes Aerobes/anaerobes Decomposers Pathogens some are photosynthetic Have no introns Includes viruses

Archaea • Single celled • Prokaryotes • Extremophiles – Methanogens – Halophiles – Thermophiles

EUKARYA • All have nucleus and • • internal organelles Includes animal and plant cells Consists of 4 kingdoms • KINGDOMS – – Protista Fungi Plantae Animalia

Kingdom: Protista

Kingdom: Fungi

Kingdom: Plantae • Multicellular • Nonmotile • Autotrophic • • (photosynthetic) Have cell walls Store sugars as starch Alternation of generations Some have vascular tissue

Kingdom: Animalia • • Multicelluar Heterotrophic Most are motile Most reproduce sexually and are diploid

Kingdom: Animalia Animal classification placed into related groups 1. Invertebrates— majority of animals which lack a backbone 2. Vertebrate-animals with a backbone Common Phyla: Porifera Cnidarians Platyhelminthes Nematodes Annelids Mollusks Arthropods Echinoderms Chordates

Evolutionary Trends A. Specialized Cells, Tissues, and Organs • As larger and more complex animals evolved, specialized cells joined together to form tissues, organs, and organ systems that work together to carry out complex functions.

Evolutionary Trends B. Body Symmetry • Radial symmetry – parts are arranged in a circle around a central point • Bilateral symmetry – parts are mirror images of each other (left and right sides) • Asymmetrical – no definite shape

Assymmetrical—Porifera

Evolutionary Trends • Whereas primitive animals exhibit radial symmetry, sophisticated animals exhibit bilateral symmetry.

Evolutionary Trends C. Cephalization • Along with bilateral symmetry came the development of cephalization, which is the concentration of sense organs and nerve cells in the front (anterior part) of the body. • The digestive, excretory, and reproductive structuress are located at the back (posterior) end. • Invertebrates with cephalization can respond to the environment in more sophisticated ways that can simpler invertebrates.

Evolutionary Trends—Cephalization

Evolutionary Trends D. Segmentation • Many animals who exhibit bilateral symmetry also have segmented bodies. • Segments have often become specialized for specific functions. • Segmentation allows an animal to increase in size.

Evolutionary Trends E. Coelom Formation • Germ layers formed early in embryonic development: – Ectoderm (outermost layer) – Mesoderm (middle layer) – Endoderm (innermost layer) • The coelom is a fluid-filled body cavity that is completely surrounded by mesoderm tissue. • It represents a significant advance in animal evolution because it provides space for elaborate organ systems.

Evolutionary Trends—Coelom Formation Types of body cavities: • Acoelomates do not have a coelom (body cavity) between their body wall and digestive cavity. • Pseudocoelomates have body cavities that are partially lined with mesoderm. • Most complex animal phyla are coelomates, meaning they have a true coelom that is lined completely with tissues from mesoderm.

Acoelomate Body covering (from ectoderm) Digestive sac (from endoderm) Tissue-filled region (from mesoderm)

Pseudocoelomate Body covering (from ectoderm) Muscle layer (from mesoderm) Digestive tract (from endoderm) Pseudocoelom

Coelomate Body covering (from ectoderm) Coelom Tissue layer lining coelom and suspending internal organs (from mesoderm) Digestive tract (from endoderm)

Coelomate

Evolutionary Trends F. Embryological Development Blastopore: first opening during the embryonic stages of an organism

Evolutionary Trends F. Embryological Development • Protostome – blastopore becomes the mouth, and the anus forms secondarily • Deuterostome – blastopore becomes the anus, and the mouth forms secondarily

Trends in Animal Development Echinoderms Chordates Annelids Mollusks Arthropods Radial Symmetry Roundworms Flatworms Cnidarians Radial Symmetry Pseudocoelom Protostome Development Three Germ Layers; Bilateral Symmetry Sponges Tissues Singlecelled ancestor Deuterostome Development Coelom

Trends in Animal Development From the Primitive • No symmetry or radial symmetry • No cephalization • 2 germ layers • Acoelomate • No true tissues • Little specialization • Sessile To the Complex • Bilateral symmetry • Cephalization with sensory apparatus • 3 germ layers • Pseudocoelomate or coelomate • Tissues, organs, and organ systems • Much specialization • Motile

Form and Function in Invertebrates Ch. 29 -2

Feeding and Digestion • The simplest animals break down food primarily through intracellular digestion, but more complex animals use extracellular digestion. • In intracellualar digestion food is digested inside the cells. – The food size must then be smaller than the cells. • In extracelluar digestion, food is broken down outside the cells. – The food size is larger than the cells of the organism.

• How does a starfish eat?

Patterns of Extracelluar Digestion • Some animals such as cnidarians and most • • • flatworms ingest food and expel wastes through a single opening. Some cells of the gastrovascular cavity secrete enzymes and absorb digested food. Other cells surround food particles and digest them in vacuoles. More complex animals digest food in a tube called the digestive tract, which may have specialized regions such as stomach and intestines.

Intestine Gizzard Crop Mouth/anus Pharynx Mouth Gastrovascular cavity Annelid Anus Gastrovascular cavity Cnidarian Pharynx Crop Arthropod Anus Pharynx Mouth/anus Mouth Flatworm Stomach and digestive glands Rectum

Respiration: Gas exchange of O 2 and CO 2 Two key features of all respiratory systems: • Respiratory organs have large surface areas that are in contact with air or water • Have ways to keep the gas exchange surfaces moist to allow diffusion to occur

Respiration Tracheal tubes Gill Siphons Movement of water Insect Mollusk Airflow Spider Book lung Spiracles

Circulation • In an open circulatory system, blood is only partially contained within a system of blood vessels. Heart (s) Blood vessels Tissues Sinuses (spongy cavities)

Circulation • In a closed circulatory system, a heart or a heart • • • -like organ forces blood through vessels that extend throughout the body. The blood stays within these blood vessels. Materials reach body tissues by diffusing across the walls of the blood vessels. Blood circulates more efficiently in a closed circulatory system.

Heartlike structure Hearts Small vessels in tissues Blood vessels Heart Sinuses and organs Heartlike structures Insect: Open Circulatory System Blood vessels Annelid: Closed Circulatory System

Excretion • The excretory system is responsible for removing waste material and conserving water. • Waste product is usually nitrogenous, meaning it contains nitrogen. • This waste is usually in the form of ammonia (NH 3), which is very toxic!

Excretion • In aquatic invertebrates, ammonia diffuses from their body tissues into the surrounding water • Terrestrial invertebrates convert: ammonia urea (less toxic) • Some insects and arachnids convert: Ammonia uric acid

Excretion Flame cells Flatworm Excretory tubules Nephrostome Excretory pore Flame cell Excretory tubule Nephridia Digestive tract Annelid Arthropod Malpighian tubules

Response—Nervous System • The nervous system gathers information from the environment. • The simplest nervous system, found in cnidarians, are nerve nets.

Trends in the Evolution of the Nervous System • Centralization—nerve cells are more concentrated (ex: ganglia) • Cephalization—high concentration of nerve cells in the anterior region (head/front) • Specialization—more developed sensory organs – To detect light, sound, chemicals, movement, etc.

Arthropod Brain Ganglia Brain Flatworm Nerve Cells Cnidarian Mollusk

Movement & Support • Most animals use Three main kinds: • skeletons • Exoskeletons • Endoskeletons specialized tissues called muscles to move, breathe, pump blood, and perform other life functions. In most animals, muscles work together with some sort of skeletal system that provides firm support. • Hydrostatic

Movement & Support • Hydrostatic skeleton – No hard structures – Lacks muscles – Water filled cavity (gastrovascular cavity) • Exoskeleton or external skeleton – Outside the body – Hard body covering made of chitin – Has to be shed (molting) • Endoskeleton – Structural support inside the body – Muscles

Reproduction • Sexual reproduction is the production of offspring from the fusion of gametes. – Maintains genetic diversity because it generates new combinations of genes • Asexual reproduction – – – Ex: Fragmentation Ex: Budding All offspring are genetically identical to parent (clones) Allows for organisms to produce offspring faster Genetic diversity decreases less able to deal with changes

Reproduction • Some organisms are hermaphrodites, meaning that they produce both sperm and egg.

Reproduction Fertilization: unification of sperm & egg • External fertilization – – Observed in less complex animals Eggs are fertilized outside the body Gametes are released in surroundings Aquatic environment – – – Observed in more complex animals Eggs are fertilized inside the female’s body Require specialized organs • Internal fertilization