The InvertebratesThe Invertebrates

Chapter 25Chapter 25

Characteristics of AnimalsCharacteristics of Animals

MulticellularMulticellular HeterotrophicHeterotrophic mostly motilemostly motile Sexual and sometimes also asexual Sexual and sometimes also asexual

repro.repro. Aerobic respiration to make ATPAerobic respiration to make ATP No cell wallsNo cell walls Cells form tissues and organsCells form tissues and organs

Animal Animal Development/TissuesDevelopment/Tissues

All animals embryos begin as a solid All animals embryos begin as a solid ball of cells. ball of cells.

This ball (a blastula) then reorganizes This ball (a blastula) then reorganizes itself into two tissue layers:itself into two tissue layers:

Early Tissue TypesEarly Tissue Types

EctodermEctoderm becomes the epidermis and becomes the epidermis and nervous system.nervous system.

EndodermEndoderm becomes the gut’s inner becomes the gut’s inner lining and the organs derived from itlining and the organs derived from it

In higher animals, a In higher animals, a mesodermmesoderm also also forms. This becomes skeleton, muscle forms. This becomes skeleton, muscle and some internal organs.and some internal organs.

The Importance of Body The Importance of Body SizeSize

Advantages to multicellular body:Advantages to multicellular body: Shelters cells from environmental Shelters cells from environmental Can consume larger food piecesCan consume larger food pieces Able to withstand the loss of some cellsAble to withstand the loss of some cells Tissue types can be differentiated to Tissue types can be differentiated to

decrease energy expenditure (assembly decrease energy expenditure (assembly line approach)line approach)

Choanoflagellates- Choanoflagellates-

Choanoflagellates- single celled, Choanoflagellates- single celled, heterotrophic, eukaryotes that can live heterotrophic, eukaryotes that can live colonially. Protozoans (animal-like colonially. Protozoans (animal-like protist)protist)

Produce signaling molecules and Produce signaling molecules and adhesion proteins which, in animals, help adhesion proteins which, in animals, help tissues form and stick together.tissues form and stick together.

Have a common ancestor with and share Have a common ancestor with and share some characteristics with sponges.some characteristics with sponges.

Body PlansBody Plans Polarity- front and back axis with Polarity- front and back axis with

anterior and posterior ends. anterior and posterior ends. Examples: Examples:

Radial Symmetry- body parts Radial Symmetry- body parts organized around an axis like spokes. organized around an axis like spokes. Examples: Examples:

Bilateral Symmetry- right and left Bilateral Symmetry- right and left halves. Examples: halves. Examples:

CephalizationCephalization

Formation of a head with concentrations of Formation of a head with concentrations of nerve and sensory cells.nerve and sensory cells.

May have evolved from colonies of cells May have evolved from colonies of cells with differentiated areas of sensory with differentiated areas of sensory perception.perception.

In higher animals, sensory organs and a In higher animals, sensory organs and a brain develop as part of cephalization.brain develop as part of cephalization.

Guts and CavitiesGuts and Cavities(sounds appealing, huh?)(sounds appealing, huh?)

Some animal digestive systems are Some animal digestive systems are “incomplete” with one opening. This sac-“incomplete” with one opening. This sac-like gut was the first to evolve. Examples: like gut was the first to evolve. Examples:

Other digestive systems are “complete” Other digestive systems are “complete” with two openings. Examples: with two openings. Examples:

This has several advantages:This has several advantages: Specialized feeding structuresSpecialized feeding structures Regionally modified tube for digestion and Regionally modified tube for digestion and

absorptionabsorption

Complete digestive systems Complete digestive systems form in two ways:form in two ways:

Protostomes- Mouth forms first then Protostomes- Mouth forms first then anusanus

Examples: all worm types, arthropods, Examples: all worm types, arthropods, mollusks (snails, slugs, octopuses)mollusks (snails, slugs, octopuses)

Deuterostomes- Anus forms first then Deuterostomes- Anus forms first then mouth Examples: Echinoderms (sea mouth Examples: Echinoderms (sea stars, sea urchins), chordatesstars, sea urchins), chordates

CoelomsCoeloms

Coelom- Coelom- body cavity between the body cavity between the gut and body wall.gut and body wall.

PeritoneumPeritoneum- lining of the coelom; - lining of the coelom; derived from mesodermderived from mesoderm

All deuterostomes have a coelom; All deuterostomes have a coelom; some protostomes have a coelomsome protostomes have a coelom

Animals

Incomplete Digestive System(Cnidarians, sponges)

CompleteDigestive System

Protostomes(mouth forms first)

Deuterostomes(anus forms first)

Acoelomates(no body cavity)

Coelomates(lined body cavity)

Pseudocoelomates(partially lined body cavity)

Reduced Coelom

SURVEY OF THE SURVEY OF THE INVERTEBRATES INVERTEBRATES

Sponges (Phylum Porifera)Sponges (Phylum Porifera) Cnidarians (Phylum Cnidaria)Cnidarians (Phylum Cnidaria) Flatworms (Phylum Platyhelminthes) Flatworms (Phylum Platyhelminthes) Segmented worms (Phylum Annelida)Segmented worms (Phylum Annelida) Mollusks (Phylum Mollusca)Mollusks (Phylum Mollusca) Round Worms (Phylum Nematoda)Round Worms (Phylum Nematoda) Arthropods (Phylum Arthropoda)Arthropods (Phylum Arthropoda) Echinoderms (Phylum Echinodermata)Echinoderms (Phylum Echinodermata)

Phylum Examples Evolutionary Milestone

Porifera sponges multicellularity

Cnidaria jellyfish, hydra, coral tissues

Platyhelminthes

flatworms bilateral symmetry

Nematoda roundworms pseudocoelom

Mollusca clams, squids, snails coelom

Annalida earthworms, leeches segmentation

Arthropodainsects, spiders, crustaceans

jointed appendages

Echinodermata

starfish deuterostomes

Chordata vertebrates notochord

 

Phylum PoriferaPhylum Poriferaspongessponges

Assymetrical animalsAssymetrical animals Filter feedersFilter feeders No tissuesNo tissues Motile sperm and larvaeMotile sperm and larvae Sessile adult stageSessile adult stage Spicules of silica in body wall Spicules of silica in body wall Asexual reproduction by budding or Asexual reproduction by budding or

fragmentation fragmentation Sexual reproduction by releasing sperm Sexual reproduction by releasing sperm

into water.into water.

Sponge Body PlanSponge Body Plan

Vocabulary:Vocabulary:osculumosculumspiculespiculeporeporecollar cellcollar cellflagellaflagellaamoeboid cellamoeboid cell

Phylum PoriferaPhylum Porifera

Phylum CnidariaPhylum Cnidariajellyfish, corals, sea anemones, jellyfish, corals, sea anemones,

etc.etc. Radially symmetricalRadially symmetrical Simplest animals with true tissues Simplest animals with true tissues

(epithelium)(epithelium) TentaclesTentacles CarnivorousCarnivorous Nematocysts- pouches which house barbs Nematocysts- pouches which house barbs

for stingingfor stinging Two tissue layers but no organsTwo tissue layers but no organs Solitary and colonial (corals)Solitary and colonial (corals) Medusa and Polyp body typesMedusa and Polyp body types

Cnidarian Body TypesCnidarian Body Types

Polyp body type

(coral)

Medusa body type

(jellyfish)

NematocystsNematocysts

Vocabulary:

Operculum

Barbs

Threads

Capsule

Nematocyst

Cnidocil

Highlighted Cnidarian GroupHighlighted Cnidarian GroupCoralsCorals

Colonial CnidarianColonial Cnidarian Calcium carbonate secretions that make Calcium carbonate secretions that make

“houses” around each polyp shaped “houses” around each polyp shaped animalanimal

Dinoflagellate symbionts (photoautotrophs Dinoflagellate symbionts (photoautotrophs in Kingdom Protista)in Kingdom Protista)

Coral reefs are the site of tremendous Coral reefs are the site of tremendous biodiversity in the ocean and are sensitive biodiversity in the ocean and are sensitive to pollution and damage.to pollution and damage.

Corals

Fire Coral

Sunflower Mushroom Coral

Phylum PlatyhelminthesPhylum PlatyhelminthesFlatworms (Planaria, Flukes, Flatworms (Planaria, Flukes,

Tapeworms)Tapeworms) Organs! Organ systems! Organs! Organ systems! Organ- two or more tissues that interact in one or Organ- two or more tissues that interact in one or

more tasksmore tasks Organ systems- two or more organs that interact Organ systems- two or more organs that interact

as they carry out specialized tasksas they carry out specialized tasks Three tissue layers- ectoderm, endoderm, and Three tissue layers- ectoderm, endoderm, and

mesodermmesoderm Bilateral, cephalized but with no coelomBilateral, cephalized but with no coelom Saclike digestive system with pharynx that sucks Saclike digestive system with pharynx that sucks

up and expelsup and expels Asexual and sexual reproduction. Many are Asexual and sexual reproduction. Many are

hermaphroditic and some can split by transverse hermaphroditic and some can split by transverse fission.fission.

Platyhelminthes Life CyclePlatyhelminthes Life CycleTape WormTape Worm

Phylum AnnelidaPhylum AnnelidaSegmented WormsSegmented Worms

Earth worms, leeches, oligochaetes, Earth worms, leeches, oligochaetes, polychaetespolychaetes

Segmented body plan- most segments similarSegmented body plan- most segments similar Tissues, organs, organ systemsTissues, organs, organ systems Closed circulatory systemClosed circulatory system Nephridia- units that help collect excess fluid Nephridia- units that help collect excess fluid

from each segment. from each segment. Susceptible to fluid loss because of flexible, Susceptible to fluid loss because of flexible,

permeable body coveringpermeable body covering

Phylum AnnelidaPhylum Annelida

Phylum MolluscaPhylum Mollusca

Bilateral, soft bodiedBilateral, soft bodied Reduced coelomReduced coelom Gills as part of the respiratory systemGills as part of the respiratory system Gastropods (snails and sea slugs), Gastropods (snails and sea slugs), Chitons , Chitons , Bivalves (clams, scallops, oysters, Bivalves (clams, scallops, oysters,

mussels) mussels) Cephalopods (squid and octopi)Cephalopods (squid and octopi)

MollusksMollusks

Phylum NematodaPhylum NematodaRoundwormsRoundworms

Most abundant living animalsMost abundant living animals Cylindrical bodies with tapered endsCylindrical bodies with tapered ends Complete gutComplete gut Most decomposersMost decomposers Some parasites (round worms, pin Some parasites (round worms, pin

worms, hookworms, worms, hookworms, trichinosis) trichinosis)

Phylum Phylum NematodaNematoda

Phylum ArthropodaPhylum ArthropodaCrabs, spiders, insectsCrabs, spiders, insects

Bilateral Bilateral jointed exoskeleton of chitinjointed exoskeleton of chitin specialized appendagesspecialized appendages OpenOpen circulatory system circulatory system Reduced coelomReduced coelom Complete gutComplete gut MoltingMolting Specialized stages of development (larvae, Specialized stages of development (larvae,

juevenile and adult)juevenile and adult)

Phylum ArthropodaPhylum Arthropoda(crabs, spiders and insects)(crabs, spiders and insects)

Crabs (and lobsters and shrimp)Crabs (and lobsters and shrimp)

• Five pairs of walking legsFive pairs of walking legs• AntennaeAntennae• Food handling appendagesFood handling appendages• Modified front appendages for Modified front appendages for

mating, defensemating, defense

Phylum ArthropodaPhylum Arthropoda(crabs, spiders and insects)(crabs, spiders and insects)

Spiders (and scorpions and ticks) Spiders (and scorpions and ticks)

• Four of walking legsFour of walking legs• Food handling appendages called Food handling appendages called

cheliceraechelicerae• Predators and parasitesPredators and parasites• Forebody and hindbodyForebody and hindbody

Phylum ArthropodaPhylum Arthropoda(crabs, spiders and insects)(crabs, spiders and insects)

InsectsInsects

• Most diverse group of animalsMost diverse group of animals• Segmented body- head, thorax and abdomenSegmented body- head, thorax and abdomen• Only winged invertebrates (most successful Only winged invertebrates (most successful

insects are winged)insects are winged)• Complete digestive systemComplete digestive system• Metamorphosis (most larvae)Metamorphosis (most larvae)• Three pairs of legsThree pairs of legs• AntennaeAntennae

Phylum EchinodermataPhylum Echinodermatasea stars, sea urchins, sand sea stars, sea urchins, sand

dollarsdollars

• spiny-skinnedspiny-skinned• Plates stiffened with calcium carbonatePlates stiffened with calcium carbonate• MarineMarine• Radially symmetricalRadially symmetrical• Tube feet as part of a water vascular Tube feet as part of a water vascular

systemsystem• PredatorsPredators• Closest relatives of the chordates (us)Closest relatives of the chordates (us)

READ CHAPTER 26READ CHAPTER 26

READ CHAPTERS 25 and 26 to be READ CHAPTERS 25 and 26 to be prepared for next weekprepared for next week

Quiz on chapter 25 next week. Lecture Quiz on chapter 25 next week. Lecture on chapt. 26on chapt. 26

Lab Practical NEXT WEEK!!!!Lab Practical NEXT WEEK!!!!