CHAPTER 26INTRODUCTION

TO ANIMALS

BIOLOGY II

ARTEMIA (BRIME SHRIMP)

http://www.youtube.com/watch?v=ZQXCa2TgcM4

Facts The Great Salt Lake brine shrimp population can produce four or

more generations per year.

Brine shrimp are crustaceans. Their closest relatives include fairy shrimp, triops and water fleas. More distant relatives include crabs, lobsters and shrimp.

Brine shrimp are used in the laboratory for testing the toxicity of chemicals.

Brine shrimp cysts have been found in Great Salt Lake geologic core samples up to 600,000 years old, so we know they've been in the area for a long time.

Brine shrimp cysts are packaged and sold as Sea-Monkeys.

Brine shrimp cysts can remain viable for up to 25 years.

Brine shrimp come in many colors. From white to pink to green, the different colors are probably an effect of diet and environmental conditions.

Taxonomy Kingdom: Animalia

Phylum: ArthropodaSubphylum: Crustacea

Class: Branchiopoda (like fairy shrimp, daphnia, tadpole shrimp)Order: Anostraca

Genus and Species: Artemia franciscana

SECTION 1- CHARACTERISTICS OF ANIMALS Purpose of this section:

Is to describe the features that all animals have in common

Learn about some of the major developments that occurred in animals as they evolved

How major groups of animals differ from each other

GENERAL FEATURES OF ANIMALS

Mites = need microscope Whales = huge

Animals are multicellular, heterotrophic organisms with cells that lack cell walls

MULTICELLULARITY All animals are multicellular (many cells) Large differences in body sizes of

animals, but most of the cells that make up these animals are similarly sized

Daphnia

Humpback Whale

STOP AND THINK What do cells need to survive?

Oxygen, source of energy, waste removal, access to water and other organic and inorganic molecules, a temperature above freezing

How do the cells that make up skin get the things they need? Depend on cells in body systems to provide

what they needExample circulatory system

HETEROTROPHY Animals are heterotrophs

Cannot make their own foodMust seek our food sources in their

environmentFood is eaten and then digested in a cavity

inside the body Some, like sponges and corals catch food that

drifts byFilter feeders

MOVEMENT

Are unique because they can perform rapid, complex movementsLack of cell wall, means greater mobilityMove by means of muscle cells that

contract with considerable force Cheetah

Chases the Gazelle Reaches speeds of 60 mph Fastest land animals

KINDS OF ANIMALS Kingdom animalia contains about 35

major divisions called phyla (singular, phylum)Often classified by development or body

characteristics

Informally grouped as invertebrates or vertebratesHowever, vertebrates make up only small

subgroup of one phylum (Chordata)Majority of animals are invertebrates

INVERTEBRATES Include any animal that does not have a

backbonePrimitive(sponges) – advanced (ants,

octopuses)Land inverts tend to be small, no skeleton

for support Ocean inverts can be extremely large, giant

squid (42 ft. in length)

Some form basis of entire ecosystemGreat Barrier Reef, 2,300 km long, made of

coral

VERTEBRATES Are chordates that have a backbone

Also have a cranium and an internal skeleton composed of bone or cartilage

Backbone supports dorsal nerve cordProvides site for muscle attachment

End 26.1

JOURNAL ENTRY – STOP AND THINK Write the date at the top of your clean

journal page.

A classmate tells you that sponges are plants because they attach themselves to

the bottom of the ocean. Is your classmate correct? Explain your answer.

26.2 ANIMAL BODY SYSTEMS Body systems allow animals to function Not all animals have every system

SUPPORTKey to success = mobility

Mobility requires the body to have supportSkeleton provides framework that supports

body

TYPES OF SKELETONS Hyrodstatic

Water-filled cavity that is under pressure Similar to balloon filled with water Ex – jellyfish

Exoskeleton Rigid external skeleton Provides surface for muscles to pull against Ex – insects, clams, crabs

Endoskeleton Made of hard material, such as bone, inside

an animal Ex – humans and other vertebrates

DIGESTION Single-celled organisms and sponges

digest food within their body cells (no digestive system)Food source cannot be larger than

individual cells All other animals digest food

extracellularly (outside of body cells) within a digestive cavityEnzymes are released into the cavity to

breakdown the food Allows animals to prey on organisms larger than

their body cells

DIGESTION, CONT. Simple animals, such as hydra and

flatworms, have a gastrovascular cavitya digestive cavity with only one opening.

Other animals have a digestive tract (gut) with two openings, a mouth and an anus.Allows for specialization

Sections of gut for food storage, breakdown of food, chemical digestion, etc.

EXCRETORY SYSTEM The removal of wastes produce by

cellular metabolismBuild up of waste products will hurt or kill an

organism Simple aquatic invertebrates

Excrete ammonia through their skin or gills Also results in loss of water

Ok, because they are in water…

Terrestrial animalsMust minimize water lossConvert ammonia to urea (component of

urine)

SIMPLE NERVOUS SYSTEMS Nerve cells (neurons) are specialized for

carrying messages in the form of electrical impulses (conduction) Coordinate to help body respond to environment

All major animal phyla except sponges have nerve cells Simplest arrangements can be found in hydras

and jellyfish Nerve cells are all similar looking and are linked in a

web called a nerve net Little coordination among nerve cells

Ganglia – clusters of neurons (found in bilaterally symmetrical animals) Can be clustered, similar to a brain

COMPLEX NERVOUS SYSTEMS Have a true brain with sensory

structures like eyes Can interact with environment in

complex ways Vertebrates have most advanced

nervous system

RESPIRATION Simple animals (jellyfish)

Oxygen gas and carbon dioxide gas are exchanged directly with the environment by diffusion

Uptake of oxygen and release of carbon dioxide (respiration) can take place only across a moist surface

Larger, complex animals Simple diffusion cannot provide adequate gas

exchange Have specialized respiratory structures

Gills – very thin projections of tissue to aid aquatic animals in respiration Not suitable in land animals because they must be kept

moist Lungs – evolved for terrestrial animals

CIRCULATION Simple animals

Body cells are exposed to either the external environment or gastrovascular cavity No body cells are far away from sources of

oxygen and nourishment

Complex animalsHave tissues that are several cell layers

thick Not close enough to surface of the cell layer to

exchange materials directly with the environmentOxygen and nutrients must be transported by

a circulatory system

TYPES OF CIRCULATORY SYSTEMS Open circulatory system

Heart pumps fluid containing oxygen and nutrients through a series of vessels out into the body cavity Fluid washes across the body’s tissues, supplying

them with oxygenFluid collects in open spaces and then flows

back to the heart

Closed circulatory system Heart pumps blood through a system of

blood vessels Form a network that permits blood flow from the

heart to all of the body’s cells and back againBlood does not come in contact with the body’s

tissues Oxygen and materials pass into and out of the

blood by diffusion through the walls of blood vessels

REPRODUCTIVE STRATEGIES Not essential to survival for an

individual organismReproduction is necessary for the survival of

a species

ASEXUAL REPRODUCTION Does not involve the fusion of two

gametesSponge – fragments it body

Each grows into a new spongeSome sea anemones pull themselves apart

to form two new adults Animals that reproduce asexually are

usually able to also reproduce sexually.

SEXUAL REPRODUCTION Organism is formed by the union of a

male and female gameteGametes are produced in sex organs

Testes produce male gametes (sperm) Ovaries produce female gametes (egg)

Hermaphrodites – have both testes and ovaries Functions as both male and female

Sperm and egg are usually produced at different times, so self-fertilization does not occur

END 26.2

26.3 EVOLUTIONARY TRENDS IN ANIMALS Animals appeared about 650 mya (in

oceans)

TISSUES Except sponges, cells of all animals are

organized into units called tissuesGroups of cells that work together to

perform a specific function

BODY SYMMETRY All animals have a body plan

Describes the shape, symmetry, and internal organization

ASSYEMETRICALSimplest body plan (sponges) IRREGULAR in shape, shape depends on

where they are growing

RADIAL SYMMETRY Have body parts arranged around a

central axis, like spokes on a bicycle wheel

A plane passing through the central axis divides the organism roughly into equal halves

Today’s radially symmetrical animals are aquaticMost drift slowly or drift in ocean currents

BILATERAL SYMMETRY Distinct left and right halves

Plane passes through body and divides the animal into mirror image halves

Major evolutionary change in animals because it allowed animals to become specializedCephalization – evolved an anterior

concentration of sensory structures Can more easily sense food and danger with

sense organs in the front.

EARLY EMBRYONIC DEVELOPMENT Cleavage – series of cell divisions Blastula – stage before gastrulation –

hollow ball of cells Gastrulation – from blastula to gastrula –

forms embryonic germ layers

BLASTULA FORMATION In all animals except sponges, the

zygote (fertilized egg cell) undergoes cell division that form a hollow ball of cells called a blastulaCells develop into three distinct layers of

cells Ectoderm Endoderm Mesoderm

Called primary tissue layers, which give rise to all of the tissues and organs in the body

TISSUE LAYERS Ectoderm

Outer layer of skin Nervous system Sense organs, such as eyes

Endoderm Lining of digestive tract Respiratory system Urinary bladder Digestive organs Liver Many glands

Mesoderm Most of the skeleton Muscles Circulatory system Reproductive organs Excretory organs

TWINS FORM IN ONE OF TWO WAYS Dizygotic (fraternal) twins results when

ovulation produces two eggs that are fertilized by different sperm Can be as genetically dissimilar as any two

siblings Monozygotic (identical) twins result when an

embryo splits in two early in cleavage, giving rise to two genetically identical embryos.

***Incidence of twin pregnancies is about 11 per 1,000 pregnancies ( 1 in 90)

***Dizygotic twins is 4-50 per 1,000 pregnancies, and monozygotic is 1-5 per 1,000

PATTERNS OF DEVELOPMENT Gastrula continues to change as it

develops Inward folding pocket becomes deeperEventually pocket breaks through the

opposite side Changes pocket to passageway

Lined with endoderm Is gut of developing embryo

Page 635 (pictures)

PROTOSTOMES Mouth develops from end of embryo

near blastoporeAnus develops at the opposite endEx – flatworms, earthworms, snails and

clams, spiders and insects, and the relatives of these animals

DEUTEROSTOMES Mouth develops from end opposite of

blastoporeAnus develops at or near blastopore

Ex – sea stars and relatives and vertebrates and relatives

First animals to have internal skeleton

INTERNAL BODY CAVITY Bilaterally symmetrical animals have

one of three basic kinds of internal body plansMay include a coelom – fluid filled space

found between the body wall and the digestive tract (gut) This space is lined with cells that come from

mesoderm

ACOELOMATES Have no body

cavity Space between

body wall and gut is completely filled with tissue

Trematoda

PSEUDOCOELOMATES Have a body cavity

located between the mesoderm and endoderm

Body cavity is called a pseudocoelom (false coelom)

Rotifera

COELOMATES Have a true coelom Provides an internal

space where mesoderm and endoderm can be in contact with each other during embryonic development

Aided in evolution of complex organs

BODY SEGMENTATION Can allow great mobility and flexibility

Earthworm can tie body in knotsLengthens and shortens body to move

Offers evolutionary flexibilitySmall change in existing segment can

produce new type of segment with different function Feeding or moving Reproduction, etc.

End 26.3

26.4 CHORDATE EVOLUTION First chordates appeared 500 mya At some point in development, all

chordates have:Dorsal nerve cordNotochordPharyngeal pouchesPostanal tail

DORSAL NERVE CORD Single, hollow dorsal nerve cord with

nerves attached to it that travel to different parts of the body

In vertebrates, develops into spinal cord

NOTOCHORD Stiff rod that develops along back of

embryo In most vertebrates, notochord only

present in the embryo

PHARYNGEAL POUCHES Series of pouches in throat Pouches of aquatic chordate embryos

develop into gills slips and portions of the gills

In land vertebrates, pouches develop into structures in head and neck, like parathyroid gland and inner ear

POSTANAL TAIL Tail that extends beyond the anus Tail allows for rapid movement underwater

(fish) Tail is used for maintaining balance (cat) Tail is only present in the embryo (humans)