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• King • Philip • Came • Over • For • Great • Spaghetti

• Kingdom• Phylum• Class• Order • Family• Genus• Species

Example Classification• Domain• Kingdom• Phylum• Class• Order• Family• Genus• Species

• Eukarya• Animalia• Chordata• Mammalia• Primate• Hominid• Homo • 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• Eukaryotic• No cell walls• Most are motile• Most reproduce sexually and are diploid

Two General Groups of Animals

• Invertebrates– No backbone– Great size range– Sea stars, worms,

jellyfish, insects– 95% of all

animal species

• Vertebrates– Backbone– Fish, amphibians,

reptiles, birds, mammals

What Animals Do To Survive

• Homeostasis: stable internal environment

• Feedback inhibition: the product or result of a process stops or limits the process

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

Asymmetrical—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 structures are located at the back (posterior) end.

• Invertebrates with cephalization can respond to the environment in more sophisticated ways than 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

Digestive sac (from endoderm)

Tissue-filled region (from mesoderm)

Body covering (from ectoderm)

Pseudocoelomate Body covering(from ectoderm)

Muscle layer(from mesoderm)

Digestive tract(from endoderm)

Pseudocoelom

Coelomate Body covering(from ectoderm)

Tissue layerlining coelomand suspendinginternal organs(from mesoderm)

Coelom

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

RadialSymmetry

Deuterostome Development

Coelom

Pseudocoelom

Protostome Development

RadialSymmetry

Three Germ Layers;Bilateral Symmetry

Tissues

Chordates Echinoderms Arthropods

Annelids Mollusks

Roundworms

Flatworms

Cnidarians

Sponges

Single-celled

ancestor

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.

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.

Arthropod

Annelid

Flatworm

Cnidarian

Mouth/anus

Mouth/anusMouth

Mouth

Gastrovascularcavity

Gastrovascularcavity

Pharynx

Pharynx

PharynxCrop

Crop

Gizzard

Intestine

Rectum

Anus

Anus

Stomachand

digestive glands

Respiration: Gas exchange of O2 and

CO2

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

MolluskInsect

Spider

Gill

Siphons

Movement of water

Booklung

Airflow

Trachealtubes

Spiracles

Circulation

• In an open circulatory system, blood is only partially contained within a system of blood vessels.

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.

Insect:Open Circulatory

System

Annelid:Closed Circulatory

System

Heartlikestructures

Bloodvessels

Heartlike structure

Small vessels in tissues

Bloodvessels

Hearts

Heart

Sinusesand organs

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 (NH3), 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

Annelid

Arthropod

Flatworm

Malpighian tubules

Digestive tract

Nephridia

Excretory pore

Excretory tubule

Flame cell

Flamecells

Excretorytubules

Nephrostome

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.

GangliaGanglia

Brain

BrainNerve Cells

Arthropod

Mollusk

CnidarianFlatworm

Movement & Support

• Most animals use 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.

Three main kinds:

• Hydrostatic skeletons• Exoskeletons• Endoskeletons

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

• Internal fertilization– Observed in more complex animals– Eggs are fertilized inside the female’s body– Require specialized organs