biol 1030 [1] - animal diversity 09 w · pdf file• two large, general ... •...

Biology 1030 Winter 2009

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Animal DiversityChapters 32, 33 and 34 (select pages)

• Three Domains of life– Bacteria

– Archaea

Living Organisms

– Archaea

– Eukarya• True nucleus

• True organelles

• Heterotrophic– Animals

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– Fungi

– Protists

• Autotrophic– Plants

– Protists


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Heterotrophic Protists• Paraphyletic grouping

– Lack chloroplasts

• Protozoans– Unicellular

• Animal-like protists– Diplomonads (Giardia)

– Ciliates (Paramecium)

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– Unikonta

• Amoebozoans

– (Amoeba)

• Opisthokonta

– (Choanoflagelates)

Choanoflagelates

• Predecessor of all

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• Predecessor of all animals

• Colonial protists

• Collared cells


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What is an Animal?• Animals are characterized by multiple traits:

M lti ll l– Multicellular

• Cells interconnected through various junctions

– Lack cell walls

– Heterotrophic

– Directional motion

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– Diplontic life cycle

– Tissues develop fromgerm layers

Animal Diversity• Over 1.5 million

described species of animalsanimals– Insects– Underestimate

• Two large, general groups of animals:

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groups of animals:

1. Invertebrates

2. Vertebrates


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Phyla• A large taxonomic grouping of related

animals

• 30-35 total phyla

• 10 ‘major’ phyla

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Phyla You Need to Know• Porifera

• Cnidaria

• Echinodermata

• Chordata

• Nematoda

• Arthropoda

• Platyhelminthes

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Platyhelminthes

• Brachiopoda

• Annelida

• Mollusca


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Animal Classification• To classify animals, we ask the following questions:

1. Are there true tissues?

2. If yes, how many layers?

3. What is the pattern of development?

4. How do they grow?

4b. Special structure?

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5. Is there body symmetry?

6. Is there a body cavity?

1. Are Tissues Present?• What is a tissue?

– A group of cells

– If one or a few cells are removed:• They cannot perform their task

• They will eventually die

• Two major groups– Parazoa

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Parazoa• Phylum Porifera

– Eumetazoa• Everything else


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Ph. Porifera• The Sponges

• The first animals

C l i l ti t– Colonial protists (Choanoflagellates)

• All are aquatic and benthic

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Poriferan Body Plan• Sponges have no true

tissuesThree layers of cells only– Three layers of cells only• Pinacoderm

– Pinacocytes– Porocytes

• Mesohyl– ‘Spongocytes’

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• Choanoderm– Choanocytes

• But…– Why not true tissues?– Totipotency


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Poriferan Body Plan• Each cell is totipotent

– Not dependent on each other

Abl t h– Able to change

– Useful for asexual reproduction

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2. How Many Tissue Layers?

• Animals with true tissues

• Invagination of a hollow ball of cells

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– Ectoderm outside

– Endoderm inside

= Diploblastic


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How Many Tissue Layers?• In most animals

– Ectoderm

– Endoderm

– Mesoderm forms between

• Two major groups:

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Two major groups:

– Diploblastic

– Triploblastic

Phylum Cnidaria• Jelly fish, anemones,

corals

• Diploblastic– Ectoderm (epidermis)

– Endoderm (gastrodermis)

– Space between is filled with mesoglea

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• 2 basic body shapes– Medusa

– Polyp


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Cnidocytes

• Nematocysts

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• Specialized stinging cell– Highly venomous

– Paralyzes prey

Cnidarian Body Plan• Colonial cnidarians

– All individuals are clones

• Corals– Autozooids are similar in

morphology

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Cnidarian Body Plan• Specialized colony

membersDactylozooid– Dactylozooid

– Gastrozooid– Gonozooid

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3. What Type of Development?• Animal development

• Diplontic life cycle

• The zygote– Undergoes cleavage

• The morula

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– A solid ball of cells

• The blastula– A hollow ball of cells


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Gastrulation• Arranges the tissue layers correctly

• Forms the primitive digestive tract or archenteron

• Creates an opening (blastopore)

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3. What Type of Development?• Fates of the blastopore:

1. Formation of the mouth

• Protostome development (mouth first)

2. Formation of the anus

• Mouth forms later

• Deuterostome

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• Deuterostomedevelopment (mouth second)


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The Deuterostomes• Radial cleavage

I d t i t d l t• Indeterminate development

• Enterocoelous– Outpockets from archenteron

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• Echinodermata

• Chordata

The Protostomes• Spiral cleavage

D t i t d l t• Determinate development

• Schizocoelous– Splitting of solid masses of mesoderm

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• The remaining phyla


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Phylum Echinodermata• Divided into 5 major classes

– Class Crinoidea

– Class Asteroidea

– Class Ophiroidea

– Class Echinoidea

– Class Holothuroidea

• All species are marine

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Echinoderm Body Plan• Larvae have bilateral

symmetry

• Pentaradial (secondary) symmetry as adults

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Echinoderm Body Plan• The water vascular system

– LocomotionGas exchange– Gas exchange

– Circulation– Prey capture

• An adaptation of their coeloms!

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Echinoderm Body Plan• All have a calcareous endoskeleton of several

plates or ossicles

– Microscopic remnants

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Echinoderm Regeneration

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Phylum Chordata• Characteristics

– Dorsal hollow nerve cord

– Notochord

– Post-anal tail

– Pharayngeal gill arches/slits

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Phylum Chordata• Three major subphyla

– Subphylum Cephalochordata

– Subphylum Urochordata

– Subphylum Vertebrata

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Pharyngeal Gill Arches• Highly modified in the

more derived h d tchordates– Ancestral uses

– Form the jaws (arch 1)

– Form the inner ear(arches 1 & 2)

– Form the cartilages of

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Form the cartilages of the throat (arches 4 & 5)


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Subphylum Cephalochordata• The lancelets

• Small, fish-like animals

O l 25 i• Only 25 species

• Filter-feeders, catching food in their 100+ gill arches

• Believed to be the earliest chordates

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– Fossils found in the Burgess Shale and Chengjiang deposits

Subphylum Urochordata • The tunicates

• Defining characteristics only in the larval stages of developmentlarval stages of development

• Most are filter-feeders, but one is an active predator

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Subphylum Vertebrata

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Recall the Protostomes• Spiral cleavage

D t i t d l t• Determinate development

• Schizocoelous– Splitting of solid masses of mesoderm

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• The remaining phyla


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4. What Type of Growth Pattern?• Two different methods of growth

– Growth by continually extending their skeletons

– Growth by moulting body coverings

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– Growth by moulting body coverings

The Lophotrochozoans• Growth by extension of

their skeletons

• A common larval form– Trochophore larva

– Annelids & Mollusks

• A feeding structureLophophore

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– Lophophore

– Brachiopods

• Neither– Platyhelminths


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The Ecdysozoans• These animals are covered

by a hard covering

• Growth occurs by moultingor shedding their cuticle or exoskeleton– Ecdysis

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• Nematodes& Arthropods

Phylum Nematoda• The round worms

• The most abundant group of the Eumetazoa– Found in all habitats

– Free-living and parasitic forms

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Nematode Body Plan• Free-living species are

generally small, interstitial worms – µm – mm scale

• Parasitic species can be very large– cm – m scale!

D l

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• Dracunculus can grow over 1m!

Nematode Body Plan• Body covering is a cuticle

– A clear, tough but flexible, non-living covering

– Not an exoskeleton

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Free-Living Nematodes

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Parasitic Nematodes

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Phylum Arthropoda• Well over 1,000,000

species described!

• It has been said that if the creationist view of the origin of species was

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correct, then God had an inordinate love of beetles – There are more species of

beetles than all other animals combined!

Phylum Arthropoda• Well over 1,000,000 species described!

• All arthropods are characterized by:

E k l t ith j i t d d• Exoskeleton with jointed appendages

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• Segmentation is obvious– Generally each segment has a pair of appendages

Arthropod Body Plan

– Similar segments are grouped into body

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regaions or tagmata

Phylum Arthropoda• Divided into multiple Subphyla including:

– Subphylum Myriapoda

– Subphylum Cheliceriformes

– Subphylum Hexapoda

– Subphylum Crustacea

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• Centipedes and millipedes

Myriapod Body Plan

• Homonomoussegmentation– Except for the head region

• Legs are simple unbranched– The major difference is the number of legs per

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The major difference is the number of legs per segment

~30 segments × 2 legs/segment =

~190 segments × 4 legs/segment =

Cheliceriform Body Plan• The spiders, mites, scorpions and ticks

• Segments are grouped into 2 tagmata

A t i h l th– Anterior cephalothorax

– Posterior abdomen

• The chelicerae (chelicera sing.)

• 4 pairs of unbranchedwalking legs

• No antennae

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• Over 1,000,000 described species!– Dominate terrestrial environments

• Light weight chitinous exoskeleton

Hexapod Body Plan

• Light-weight chitinous exoskeleton

• Three tagmata

– Head – 5 segments

– Thorax – 3 segments

• Legs and wings

– Abdomen – up to 11

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Abdomen up to 11

Crustacean Body Plan• The crabs, lobsters, shrimp, barnacles, copepods

– Mostly aquatic with a few terrestrial species

H l i• Heavy calcarious carapace

• Body divided into 2 tagmata

– Cephalothorax• Biramous appendages

• Several pairs of antennae

– Abdomen – or tail

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The Lophotrochozoans• Growth by extension of

their skeletons

• A common larval form– Trochophore larva

– Annelids & Mollusks

• A feeding structureLophophore

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– Lophophore

– Brachiopods

• Neither– Platyhelminths

Phylum Platyhelminthes• The flat worms

• Possess neither a trochophore larvae or a lophophore

• 3 major classes– Class Turbellaria

– Class Cestoda

– Class Trematoda

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• They have a solid body construction

– Acoelomate

Platyhelminth Body Plan

• All flat worms exhibit bilateral symmetry

– Rudimentary light-sensitive eye-spots

• Flat worms have an incomplete, two-way gut

– The gastrovascular cavity

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Phylum Platyhelminthes

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Phylum Brachiopoda• The lamp shells

• One of a few lophophorate phyla

• Not clams!– Different plane of symmetry

– Different mode of life

– Different musculature

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Brachiopod Body Plan• Most are sessile - pedicle

– Some dig through the sand

• Valves are produced by a mantle as in the molluscs– Predominant in the fossil

record

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Protostome Development?• Cleavage is radial

• The second opening becomes the mouth– The blastopore disappearsp pp

• The third opening becomes the anus (if it forms)– The Inarticulata have a complete, 1-way gut

– The Articulata have an incomplete, 2-way gut

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Phylum Annelida• The segmented worms

• Three major classes

– Class Polychaeta

– Class Oligocaeta

– Class Hirudinea

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Annelid Body Plan• Obvious segmentation

– In many, the segments are all similar –hhomonomous

– Others have segments that are specialized –heteronomous

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Annelid Body Plan• Trochophore larval

• Paired setae (chaetae) on nearly all segmentsPolychaetae– Polychaetae –

– Oigochaetae –

– Hirudinea –

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Polychaete Body Plan• Predominantly marine worms with

parapodia on each segmentM ltit ki– Multitasking

• Well-developed head with palps– Multitasking

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Oligochaete Body Plan• Mainly terrestrial (some freshwater) worms

– No parapodia, & small setae or bristles• Streamline body shape

– Reduced head• No palps

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Hirudinean Body Plan• Body is dorsoventrally flattened

– Anterior and posterior suckers

• Segmentation is reduced to accommodate large blood meals

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Phylum Mollusca• All with a trochophore larval stage• Can be found in all environments marine, freshwater

and terrestrial (moist habitats)and terrestrial (moist habitats)• Four major classes

– Class Polyplacophora– Class Gastropoda– Class Bivalvia– Class Cephalopoda

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Molluscan Body Plan• Despite this variety all mollusks are

variations on a common theme

1. Muscular foot

2. Mantle

3. Radula

4. Visceral mass

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• A great example of adaptive radiation

Class Polyplacophora• The chitons

• Muscular foot for crawling

• Flexible 8-piece shell

• Tongue-like radula

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Class Gastropoda• The snails and slugs

• Crawling muscular foot

• Single spiral shell– slugs

• Tongue-like radula

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Class Bivalvia• The clams, scallops, mussels etc.

• Digging foot in some

• Shell in 2 hinged pieces

• No radula

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• The squid & octopi

• Foot modified into tentacles

Class Cephalopoda

• Shell reduced or absent

• Beak-like radula

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5. Type of Body Symmetry?• Most sponges (parazoa) are asymmetrical

– A ‘random’ growth of cells with no plane of tsymmetry

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5. Type of Body Symmetry?• The ancestral eumetazoan character trait is

radial symmetry– Where there are several planes of symmetry

– Radial animals are divided on an oral-aboral axis

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5. Type of Body Symmetry?• The more derived trait is bilateral symmetry

– Only a single plane creates two ‘equal’ halves• Bilateral animals have multiple axes or ‘sides’

– Anterior – Posterior

– Dorsal – Ventral

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Cephalization• Two major groups of animals

– Radiata– Bilateria

• The concentration of sensory organs at the anterior end

• Clustering of neurons

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g– Ganglia

– Brains

• Complex behaviours

6. Is There a Body Cavity?• The body cavity is called the coelom

– The fluid-filled space around internal organs

– Room for internal organs to expand and move

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• Only looked at in triploblastic animals


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6. Is There a Body Cavity?• Eucoelomate

– A cavity completely lined with mesodermlined with mesoderm

• Pseudocoelomate

– A cavity partially linedwith mesoderm (and endoderm)

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• Acoelomate

– No cavity

– The ‘space’ is completely filled with mesoderm

Animal Phylogeny• The traditional

phylogenetic tree –shared charactersshared characters– Anatomical features

– Developmental characters

– Embryological characters

• New technologies –molecular data

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molecular data– DNA and rRNA sequencing

• Molecular phylogeny

Read Concept 32.4

biol 1030 [1] - animal diversity 09 w · pdf file• two large, general ... •...

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