Introduction to animals

Introduction Introduction to Animalsto Animals

Characteristics of Characteristics of AnimalsAnimals

•All multicellular Eukaryotes

Heterotrophs (take in food and internally digest it)

•Store food reserves in the liver as glycogen

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

Atom

Molecule or

compound

Organelle

CELLLevels of Levels of OrganizationOrganization

TissueOrga

nOrgan syste

mOrganism

Life begins

Invertebrate groupsInvertebrate 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

1. Phylum Porifera(Sponges)

Sponge - PoriferaSponge - Porifera

Osculum of

Sponge

Phylum Porifera (Sponges)(exit for water)

(digest and distribute food)

(skeleton)

Choanaocyte

*** Sponges are Parazoans: they contain NO true tissues

*** Sponges are filter feeders

2. Phylum Cnidaria

Jellyfish, Corals, and other Stingers

General Characteristics

• Simple body plan-bag shaped organism• Radially symmetrical organization

• Consists of a mouth and a sac-like cavity• Lacks an anus

• The mouth is surrounded by a ring of tentacles

• The cavity in the center of the gut, called the gastrovascular cavity.

Two Body Forms

• Polyps- attached to a surface- ex: sea anemones- mouth points up

• Medusae- free floating-ex: jellyfish-mouth points down

Sea Anemone - CnidariaSea Anemone - Cnidaria

Tentacles of Sea Anemone

More CnidariansMore Cnidarians

Brain Coral

Red jellyfish

3. Phylum Platyhelminthes

(Flatworms)• Platyhelminthes consists of three kinds of acoelomate flatworms.

• 1. Free-living Flatworms: such as planarians, which are carnivorous

scavengers.• 2. Flukes: are internal, or external,

parasites that suck tissue fluids or blood.• 3. Tapeworms: internal parasites that live

in the intestinal tracts of vertebrates.

Flatworms - Flatworms - PlatyhelminthesPlatyhelminthes

Planarian

Marine Flatworm

Planaria

Tapeworm Scolex (head) Young

Proglottids

Old

Proglottids

** tapeworms appear to be segmented, but they are not true “segmented” worms

4. Phylum Nematoda(Roundworms)• Found in fresh water, marine, moist soil, tissues of

plants, and tissues and body fluids of animals

• A complete digestive tract is present and nutrients are transported through the body in the pseudocoelomic fluid.

• Free-living forms are important in decomposition

• Animal parasitic forms can be hazardous to health.

(Trichinella spiralis in humans via undercooked infected pork)

Nematode

Nematode

7. Phylum Annelid(Segmented Worms: includes

leeches, earthworms and polychaetes)

Leeches are freshwater but some are terrestrial in moist vegetation. Many are carnivorous and feed on small invertebrates, while some attach temporarily to animals to feed on blood. They have 2 suckers, one at each end.

leech

•Earthworms ingest soil, extract nutrients in the digestive system and deposit undigested material (mixed with mucus from the digestive tract) as casts through the anus. Important to farmers as they till the soil and castings improve soil texture

Polychaetae drift and swim in the plankton, some crawl along the sea floor, and many live in tubes they construct by mixing sand and shell bits with mucus.

Tube-dwellers include the fanworms that feed by trapping suspended food particles in their feathery filters which are extended from the tubes.

Phylum Annelid

Fanworm

Polychaete Worm

6. Phylum Mollusca(snails, bivalves, octopuses and

squids)• In Squids, the shell is

reduced and is internal.

• In octopuses, the shell is entirely absent.

• Octopuses have a highly developed

nervous system with a large, complex brain.

Snails

Mollusca (With and Without Shells)

snail scallop

nautilus nudibranch

octopus

8. Phylum Arthropoda(spiders, insects, crustaceans, and

various related organisms)

• Arthropods have two kinds of life cycles…(1) complete metamorphosis,

(2) incomplete metamorphosis.• Arthropods have: * jointed

appendages, * a well-developed nervous system, * specialized body

segments, and * an exoskeleton made of chiton.

The specialized body segments are the: Head, Thorax and Abdomen

Incomplete Metamorphosis (immature forms are often called nymphs)

Nymphs resemble the adult in form except for being smaller and lacking fully developed wings and sexual

organs. Life Cycle: Egg nymph adult

Complete metamorphosisImmature forms are called larvae (larva, singular).

The pupal stage is a transition stage, when the larva is transformed to the adult.

Pupa molts to the adult form. Life Cycle: Egg --> larva --> pupa --> adult

Arthropoda (insects, spiders, crustaceans,

horseshoe crab)

Dung beetle

Horseshoe crab

crayfishspider

9. Phylum Echinodermata

(sea stars (starfish), sea urchins and sand dollars)Echinoderms are Coelomates Deuterostomes

Echinoderms have complete digestive systems

Although some adults exhibit radial symmetry, some

features are bilateral, as are the body shapes of their

larvae.

EchinodermsEchinoderms

Sea cucumber

Sand dollar

starfish

Brittle star

Sea fan (crinoid)

VertebratVertebrate Groupse Groups

10. Phylum Chordata

• The Phylum Chordata consists of animals that

exhibit the following four features. In many cases, these features

are temporary, appearing only during

embryonic development.

1. A Notochord• A notochord provides support

for the body. It is a flexible cord

located on the dorsal surface. In most cases, the

notochord is replaced by bone

during development.

Notochord

2. A Dorsal Hollow Nerve

Cord• A dorsal hollow nerve cord forms the basis of the nervous system.

In some chordates, the

nerve cord becomes the

brain and spinal cord.

3. Pharyngeal Gill Slits• Pharyngeal Gill Slits provides

channels across the pharynx to the outside of the body. In some chordates, the slits become gills

for oxygen exchange, or for filter feeding, while in others,

the slits disappear during embryonic development.

4. A Muscular Tail

• A muscular tail extends beyond the digestive system. In

many chordates, such as humans, the tail is lost during embryonic

development.

There are Two Groups of Chordates• 1. Invertebrate Chordates: includes

lancelets and tunicates.

• 2. Vertebrate Chordates: includes sharks, fish, amphibians, reptiles,

birds and mammals. Vertebrate Chordates are characteristics by a

series of bones, the vertebrae, that enclose the spinal cord.

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 opening is called the blastopore

• The center is the primitive gut or Archenteron blastopore

Archenteron

Tissue DevelopmentTissue Development• Blastopore may become the

mouth (Protostome) or anus (Deuterostome)

• Protostomes (mollusks, arthropods, & annelids)

• Deuterostomes (echinoderms & vertebrates)

• Some animals form a middle germ layer called mesoderm

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

•Cnidarians have outer epidermis & inner gastrodermis with jelly-like mesoglea between the layers

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)

Open Circulati

on

Closed Circulati

on