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Parazoa – Phylum Porifera

Sponges Loosely organized and lack tissues Multicellular with several types of cells 8,000 species mostly marine Adults sessile, larvae free-swimming

Phylum Porifera

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Radiata – Phyla Cnidaria and Ctenophora

Radial symmetry Mostly marine Only 2 embryonic germ layers – diploblastic

Ectoderm and endoderm Mesoglea connects 2 layers Gastrovascular cavity for extracellular digestion True nerve cells arranged in nerve net

No central control organ

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Phylum Cnidaria 2 different body forms

Sessile polyp – tubular body with tentacles surrounding opening (mouth and anus)

Motile medusa – umbrella-shaped body with a mouth on the underside surrounded by tentacles

Cnidocytes contain nemotocystsHairlike trigger – cnidocilSome sticky while other sting

Simple muscles and nervesNot true muscles with mesoderm

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Phylum Platyhelminthes

Flatworms Lack a specialized respiratory or circulatory

system to transport gases Bilaterally symmetrical with a head First with 3 embryonic germ layers – triploblastic Mesoderm key innovation – led to more

sophisticated organs Acoelomate – lacking fluid-filled cavity Some are important parasites

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Phylum Nematoda

Roundworms In nearly all habitats from poles to tropics Over 100,000 species Tough cuticle covers body Longitudinal but not circular muscles Pseudocoelom acts as hydrostatic skeleton

and circulatory system Complete digestive tract

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Phylum Rotifera

Named for ciliated crown or corona 1800 species – mostly freshwater Digestive tract with mouth and anus – mastax Pseudocoelom Reproduction unique

Parthenogenesis – amictic eggs – unfertilized diploid eggs

Mictic eggs –haploid eggs become males

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Phylum Mollusca

Over 100,000 species Soft body with, protective external shell***** Body has 3 parts

Foot, visceral mass and mantle Eucoelomate Open circulatory system

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Fiorito and Scotto’s Experiments Showed Invertebrates Can Exhibit Sophisticated Observational Learning Behavior

Octopuses trained to attack red or white ball using reward and punishment

Classical conditioning Color blind so must see relative brightness of

balls Observer octopuses watched trained

octopuses attack ball Observers learned faster than original training

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Phylum Annelida

Rings are distinct segments separated by a septum

Segmentation has advantages1. Repetition of components provides backup2. Coelom acts as hydrostatic skeleton3. Permits specialization

Double transport system Circulatory system and coelomic fluid carries

nutrients, wastes and respiratory gases

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Digestive system complete and unsegmented Sexual reproduction involves 2 individuals

(sometimes separate sexes other hermaphroditic) with internal fertilization

Asexual reproduction by fission 15,000 species All annelids except leeches have setae on

each segment 3 classes – Polychaeta, Oligochaeta and

Hirudinea

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Phylum Arthropoda

Perhaps most successful phylum ¾ of all described living species Success related to body plan of all major

biomes Exoskeleton made of chitin and protein

Can be extremely tough or soft and flexibleRelatively impermeable to water

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Segmented with appendages for locomotion, food handling, or reproduction

Tagmata – fused body segments Extensive cephalization

Well developed organs for sight, touch, smell, hearing and balance

Compound eyes – ommatidia Sophisticated brain with 2 or 3 ganglia

connected to several smaller ventral nerve ganglia

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Open circulatory system Gas exchange – gills, tracheal system with

spiracles or book lungs Complex digestive system Excretion – metanephridia or Malpighian

tubules 6 main classes – Trilobita, Arachnida,

Diplopoda, Chilopoda, Insecta and Crustacea

Success of Arthropoda

Exoskeleton Regional Specialization

Restriction Divergence Fusion

Body Appendages Internal Anatomy

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Trilobita Extinct early arthropods, bottom feeders, little

specialization of body segments

Arachnida Spiders, scorpions, ticks and mites 2 tagmata- cephalothorax and abdomen

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Diplopoda – millipedes 2 pairs of legs per segment, herbivorous

Chilopoda – centipedes 1 pair of legs per segment, carnivorous

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InsectaMore species of insects than all other animal

species combinedWings crucial to success – outgrowths of body

wall35 orders – differences in wings and mouthpartsSeparate sexes with internal fertilizationMetamorphosis

Complete – 4 stages with adult and larval stages very different

Incomplete – 3 stages with young resembling miniature adults

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CrustaceaCrabs, lobsters, barnacles and shrimpMarine, fresh water and terrestrialUnique 2 pair of antennaeMandibles, maxillae and maxillipedsSwimmeretsCuticle covering head extends over

cephalothoraxNauplius larvae very different from adult

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Deuterostomia: Echinodermataand Chordates Phylum Echinodermata

Modified radial symmetry – 5 parts Secondary – larvae are bilateral

Cephalization absentNo brain – simple nervous systemEndoskelton covered with spines and

pedicellariaeWater vascular system with tube feet functions

in movement, gas exchange and feeding

Echinodermata

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No excretory organs – respiration and excretion by diffusion

Autotomy – intentionally detach body part that will later regenerate

Reproduce sexually with separate sexes External fertilization

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Phylum Chordata

4 key distinguishing innovations1. Notochord – single flexible rod2. Dorsal hollow nerve cord3. Pharyngeal slits4. Postanal tail All chordates exhibit these at some time during

development Subphylum Vertebrata – fish, birds,

amphibians, reptiles, mammals

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Phylum Chordata