AS ORGANISMS EVOLVED THEIR BODY SYSTEMS

BECAME MORE COMPLEX

Evolution of Organ Systems

Complex animals tend to have high levels of cell specialization and internal body organization, bilateral body symmetry, a front end or head

with sense organs, and a body cavity.With the exception of sponges, every kind of animal exhibits some type of body symmetry in its anatomy,

or body structure.

Body Symmetry

Body Symmetry

Asymmetry no planes can be drawn through the body and create

equal halves

radial symmetry similar to that of a bicycle wheel, in which any

number of imaginary planes can be drawn through the center, each dividing the body into equal halves.

bilateral symmetry a single imaginary plane can divide the body into two

equal halves.

RadialRadial BilateralBilateral

Body Symmetry

MOST COMPLEX ANIMAL PHYLA HAVE A TRUE COELOM THAT IS

LINED COMPLETELY WITH TISSUE DERIVED FROM MESODERM.

Body Cavity

Body Cavity

Acoelomates meaning that no coelom, or body cavity, forms

between the germ layers.

Pseudocoelomates body cavity lined partially with mesoderm

(roundworms)

Coelomates   completely with tissue derived from mesoderm.

Body Cavity Comparison

USUALLY ONE OF THREE MAIN KINDS OF SKELETAL SYSTEMS: HYDROSTATIC SKELETONS, EXOSKELETONS, OR

ENDOSKELETONS.

Skeletal System

Skeletal System

No skeleton instead spicules (sponge) or some other form of support

(muscles)Hydrostatic skeleton

muscles surround a fluid-filled body cavity that supports the muscles. When the muscles contract, they push against fluid in the body cavity, causing the body to change shape.

Exoskeleton external skeleton, is a hard body covering made of

chitin.Endoskeleton

structural support located inside the body.

Hydrostatic skeletonHydrostatic skeleton EndoskeletonEndoskeleton

Skeletal system

RESPIRATORY ORGANS HAVE LARGE SURFACE AREAS THAT ARE IN CONTACT

WITH THE AIR OR WATER. ALSO, FOR DIFFUSION TO OCCUR, THE RESPIRATORY

SURFACES MUST BE MOIST.

Respiratory System

Respiratory System

Diffusion respire through their skins

Gills feathery structures that expose a large surface area to the water. Gills

are rich in blood vessels that bring blood close to the surface for gas exchange.

Book lungs parallel, sheetlike layers of thin tissues that contain blood vessels.

Spiracles in insects, air enters the body through openings called spiracles. It

then enters a network of tracheal tubes, where gases diffuse in and out of surrounding body fluids.

Lungs Inhaling brings oxygen-rich air from outside the body through the

trachea (TRAY-kee-uh) and into the lungs. The oxygen diffuses into the blood inside the lung capillaries.

GillsGills Book LungsBook Lungs

Respiratory System

SpiraclesSpiracles LungsLungs

Respiratory System

MOST ANIMALS HAVE AN EXCRETORY SYSTEM THAT RIDS THE BODY OF

METABOLIC WASTES WHILE CONTROLLING THE AMOUNT OF WATER IN THE TISSUES.

Excretory System

Excretory System

Diffusion ammonia diffuses from their body tissues into the

surrounding water. Nephridia

annelids and mollusks, urine forms in tubelike structures called nephridia. Fluid enters the nephridia through openings called nephrostomes. Urine leaves the body through excretory pores.

Malpighian Tubes saclike organs that convert ammonia into uric acid.

Kidneys urea is removed from the bloodstream along with other

metabolic wastes Cloaca- frogs only one tube for solid and liquid waste Humans- two tubes one for solid waste the other for liquid

waste

CloacaCloaca Malpighian TubesMalpighian Tubes

Excretatory System

MOST INVERTEBRATES REPRODUCE SEXUALLY DURING AT LEAST PART OF THEIR LIFE CYCLE. DEPENDING ON

ENVIRONMENTAL CONDITIONS, HOWEVER, MANY INVERTEBRATES MAY ALSO REPRODUCE ASEXUALLY.

MOST VERTEBRATES REPRODUCE SEXUALLY

Reproductive System

Reproductive System

Asexually only need one

Sexually need two

Internal eggs are fertilized inside the female's body.

External eggs are fertilized outside the female's body

MOST COMPLEX ANIMALS MOVE BLOOD THROUGH THEIR BODIES USING ONE OR MORE HEARTS AND EITHER AN OPEN OR

CLOSED CIRCULATORY SYSTEM.

Circulatory System

Circulatory System

DiffusionOpen system

blood is only partially contained within a system of blood vessels. Instead, one or more hearts or heartlike organs pump blood through blood vessels into a system of sinuses, or spongy cavities. The blood comes in direct contact with the tissues and eventually makes its way back to the heart.

Closed system a heart or heartlike 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. Frog

three chamber heart Human

four chamber heart

Open SystemOpen System Closed SystemClosed System

Circulatory System

Circulatory System

Single and Double Loop

How Does Blood flow?How Does Blood flow?

Human Circulatory System

THE SIMPLEST ANIMALS BREAK DOWN FOOD PRIMARILY THROUGH INTRACELLULAR

DIGESTION, BUT MORE COMPLEX ANIMALS USE EXTRACELLULAR DIGESTION.

Digestive System

Digestive System

Intracellular food is digested inside cells

Simple animals such as cnidarians and most flatworms ingest food and expel wastes through a single opening.

filter feedersExtracellular

food is broken down outside the cells in a digestive cavity or tract and then absorbed into the body. More-complex animals digest food in a tube called the

digestive tract. Food enters the body through the mouth, and wastes leave through the anus. One way track

• Mouth/anus• characteristic of roundworms, mollusks, arthropods, and

echinoderms Two way track

• Mouth and anus

One way trackOne way track Two way trackTwo way track

Digestive System

INVERTEBRATES SHOW THREE TRENDS IN THE EVOLUTION OF THE NERVOUS SYSTEM: CENTRALIZATION, CEPHALIZATION, AND

SPECIALIZATION. NONVERTEBRATE CHORDATES HAVE A RELATIVELY SIMPLE NERVOUS

SYSTEM WITH A MASS OF NERVE CELLS THAT FORM A BRAIN. VERTEBRATES HAVE A MORE COMPLEX BRAIN WITH DISTINCT REGIONS,

EACH WITH A DIFFERENT FUNCTION.

Nervous System

Nervous System

Centralization Nerve Nets

consist of individual nerve cells that form a netlike arrangement throughout the animal's body.

Cephalization concentration of nerve tissue and organs in one end of the

body Vertebrates display a high degree of cephalization, or

concentration of sense organs and nerve cells at the front of the body. The head contains a well-developed brain The cerebrum is the “thinking” region of the brain.

Specialization specialized sense organs that detect light, sound, chemicals,

movement, and even electricity to help them discover what is happening around them.

Comparison and Complexity of Nervous Systems

Human Body Exhibit

THE END