Introduction to animals

Introduction Introduction to Animalsto Animals

TraitsTraits

Characteristics of Characteristics of AnimalsAnimals

•All multicellular (metazoans)

•Eukaryotes (cells with nucleus & organelles)

• Ingestive heterotrophs (take in food and internally digest it)

•Store food reserves in the liver as glycogen

Lions Feeding Lions Feeding (Ingestion)(Ingestion)

Support SystemsSupport Systems• Have some type of skeletal support• Endoskeleton inside and made of

cartilage &/or bone• Exoskeletons found in arthropods

– Cover the outside of the body– Limit size– Must be molted making animal

vulnerable to predators

Cicada Molting Cicada Molting ExoskeletonExoskeleton

Support SystemsSupport Systems

• Worms and echinoderms (starfish) have fluid-filled internal cavities giving them support

• Called hydrostatic skeletons

MovementMovement•Animals such as sponges may

be sessile (attached & non-moving)

•Animals that move very little are said to be sedentary (clam)

•Animals that can move are motile

•Have muscular tissue to provide energy for movement

SESSILE SEDENTARY

MOTILE

Sponge Chiton

Cheetah

Reproduction in Reproduction in AnimalsAnimals

• All animals are capable of sexual reproduction

• Some animals like sponges and earthworms are hermaphrodites producing both eggs and sperm

• Hermaphrodites may exchange sperm and NOT fertilize their own eggs

Leeches Exchange Leeches Exchange Sperm During MatingSperm During Mating

Mating

leech

Reproduction in Reproduction in AnimalsAnimals

• Females of some animals produce eggs, but the eggs develop without being fertilized

• Called Parthenogenesis• New offspring will be all

female Parthenogenesis occurs in some fishes, several kinds of insects, and a few species of frogs and lizards

Parthenogenesis in the Parthenogenesis in the Komodo DragonKomodo Dragon

Mating Mating and and

Mating Mating BehaviorsBehaviors

Beetles

Mating

Male

Female

Young

Courtship

Levels of OrganizationLevels of Organization

• Sponges are the ONLY animals that have just the cellular level

• All other animals show these levels – cell, tissue, organ, and system

• Cells may specialize (take own different shapes and functions)

• Cells are held together by cell junctions to form tissues

InvertebratInvertebrate groupse groups

Characteristics of Characteristics of InvertebratesInvertebrates

• Simplest animals• Contain the greatest number

of different species • Most are aquatic (found in

water)• Do NOT have a backbone• Includes sponges, cnidarians,

flatworms, roundworms, annelids, mollusks, arthropods, and echinoderms

Sponge - PoriferaSponge - Porifera

Osculum of

Sponge

Sea Anemone - CnidariaSea Anemone - Cnidaria

Tentacles of Sea Anemone

More CnidariansMore Cnidarians

Brain Coral

Red jellyfish

Flatworms - Flatworms - PlatyhelminthesPlatyhelminthes

Planarian

Marine Flatworm

Roundworms (Nematoda) Roundworms (Nematoda) and Segmented Worms and Segmented Worms

(Annelida)(Annelida)

Nematode Leech (segmented worm)

Mollusca (With and Without Shells)

snail scallop

nautilus nudibranch

octopus

Arthropoda (insects, spiders, crustaceans,

horseshoe crab)

Dung beetle

Horseshoe crab

crayfishspider

EchinodermsEchinoderms

Sea cucumber

Sand dollar

starfish

Brittle star

Sea fan (crinoid)

VertebratVertebrate Groupse Groups

VertebrataVertebrata

•More complex animals•Most have a backbone

made up of individual bones called vertebrae

•From simplest to most complex, the phylum includes: fish, amphibians, reptiles, birds, and mammals

Vertebrate BackboneVertebrate Backbone

VertebrataVertebrata• Vertebrates have

endoskeletons (internal)• Some vertebrates have

skeletons of cartilage (sharks, rays, and skates)

• Other vertebrates have skeletons of bone and cartilage (reptiles, birds, & mammals)

Bone & Cartilage in Bone & Cartilage in FetusFetus

FishFish

lancelet ray

anglerfish

damselfish

AmphibiaAmphibia

toad

newt

frog

salamander

ReptiliaReptilia

Turtle

Snake

Alligator

Lizard

Birds - AvesBirds - Aves

hummingbird ostric

hlovebirds

MammaliaMammalia

Body Body AreasAreas

Surfaces• Dorsal – back or upper surface• Ventral – belly or lower surface• Anterior – head or front end• Posterior – tail or hind end

opposite the head• Oral surface (echinoderms) – is

where the mouth is located (underside)

• Aboral surface (echinoderms) – is opposite the mouth (top side)

DORSAL

VENTRAL

Surfaces (Most Surfaces (Most Animals)Animals)

ANTERIOR POSTERIOR

Surfaces (Echinoderms)Surfaces (Echinoderms)

ORALABORAL

mouth

Symmetry

Body SymmetryBody Symmetry

Body SymmetryBody Symmetry

• Symmetry is the arrangement of body parts around a central plane or axis

• Asymmetry occurs when the body can’t be divided into similar sections (sponges)

Body SymmetryBody Symmetry

•Radial symmetry occurs when body parts are arranged around a central point like spokes on a wheel (echinoderms)

•Most animals with radial symmetry are sessile (attached) or sedentary (move very little)

Body SymmetryBody Symmetry

•Bilateral symmetry occurs when animals can be divided into equal halves along a single plane

•Organisms will have right and left sides that are mirror images of each other

•More complex type of symmetry

Body SymmetryBody Symmetry

• Animals with bilateral symmetry are usually motile

• Animals have an anterior and posterior ends

• Show cephalization (concentration of sensory organs on the head or anterior end)

Segmentation

SegmentationSegmentation• Occurs whenever animal bodies

are divided into repeating units or segments

• Found in more complex animals• Earthworms show external

segmentation• Humans show internal

segmentation (backbone)• Segments may fuse

(cephalothorax)

SegmentationSegmentation

cephalothorax

TissueTissuess

Tissue DevelopmentTissue Development

• Zygote (fertilized egg) undergoes rapid cell divisions called cleavage

• Forms a hollow ball of cells called the blastula

BlastulaBlastula•The blastocoel is the center cavity of the blastula with 1 germ layer (blastoderm)

Tissue DevelopmentTissue Development• The blastula

INVAGINATES (folds inward at one point)

• • Called

Gastrulation

• The center is the primitive gut or Archenteron blastopore

Archenteron

Embryonic Embryonic DevelopmentDevelopment

Germ LayersGerm Layers• Form tissues,

organs, & systems• NOT present in

sponges• Ectoderm (outer) –

forms skin, nerves, sense organs

• Endoderm (inner) – forms liver and lungs

• Mesoderm (middle) – forms muscles & other systems

Body LayersBody Layers•Sponges have NO tissues or organs, only specialized cells

•Cnidarians like jellyfish & coral have only two body layers & one body opening (mouth/anus) into gastrovascular cavity

Body LayersBody Layers

• All worms, mollusks, arthropods, echinoderms, and vertebrates have three cell layers– Ectoderm– Endoderm– mesoderm

Embryonic Embryonic CleavageCleavage

CleavageCleavage• Cleavage – rapid

mitosis (cell division) of zygote

• Radial Cleavage – cells divide parallel or perpendicular to axis to each other

CleavageCleavage• Spiral Cleavage –

cellular divisions occur diagonally, in a twisting pattern

Stages of Development

Larval FormsLarval Forms• Animals with Indirect

development• Go through immature (larval)

forms• Larva does NOT resemble

adult• Cnidarian (jellyfish, coral, &

sea anemone) larva called Planula

Larval FormsLarval Forms•Mollusk (squid & octopus)

larva called trochophore•Echinoderm (starfish) larva

is called Dipleurula

MetamorphosisMetamorphosis

•Usually found in arthropods•May be complete or

incomplete• Incomplete Metamorphosis: egg nymph adult•Complete Metamorphosis: egg larva pupa adult

MetamorphosisMetamorphosis

COMPLETE INCOMPLETE

Body Body CavitiesCavities

Coelom - Body CavityCoelom - Body Cavity• Internal body cavity fully

lined with mesoderm•Body organs suspended in

this cavity

Coelom - Body CavityCoelom - Body Cavity• Acoelomate animals have

solid bodies filled with cells• Acoelomate animals include

sponges, cnidarians, & flatworms

Coelom - Body CavityCoelom - Body Cavity

•Pseudocoelomate animals (roundworms) have a functional body cavity NOT fully lined with mesoderm

Animal SystemsAnimal Systems

Support SystemsSupport Systems• Spongin & spicules (sponges)• Limestone cases (corals)• Exoskeletons of Chitin

(arthropods)– Must be shed or molted to grow

• Inner Calcium plates or Test (echinoderms)

• Bone/cartilage endoskeleton (vertebrates)

Digestive SystemsDigestive Systems•All animals are ingestive

heterotrophs•Choanocytes (specialized

cells) capture & digest food for sponges

•Gastrovascular cavity with one opening in cnidarians and flatworms for food to enter & leave; called two-way digestive system

Two-Way DigestionTwo-Way Digestion

Digestive SystemsDigestive Systems• Animals with a one-way

digestive system have a mouth and an anus

• Food enters the mouth, continues in one direction through the digestive tract, and wastes leave through the anus

• Includes annelids, arthropods, & vertebrates

One-Way DigestionOne-Way Digestion

Mouth

anus

Circulatory SystemsCirculatory Systems

•Transports oxygen & nutrients to cells

•Carries away wastes & carbon dioxide from cells

•Sponges, cnidarians, & flatworms do NOT have circulatory systems

Circulatory SystemsCirculatory Systems

• In closed circulation, blood remains inside blood vessels until it reaches cells (annelids & vertebrates)

• In open circulation, blood is pumped out of blood vessels to bathe tissues in the body cavity or hemocoel (arthropods & mollusks)